A History of Inventions, Discoveries, and Origins, Volume I (of 2)

In the last century, some artists in Germany first fell upon the method of employing gold instead of iron, and of thereby making artificial rubies, which when they were well set could deceive the eye of a connoisseur, unless he tried them with a diamond or a file. The usual method was to dissolve the gold in aqua regia, and to precipitate it by a solution of tin, when it assumed the form of a purple-coloured powder. This substance, which must be mixed with the best frit, is called the precipitate of Cassius, gold-purple, or mineral-purple[315 - [The extensive use of this substance in colouring glass and porcelain has rendered its best and most œconomical preparation a subject of interest both to the chemist and the manufacturer. Although the determination of its true chemical composition has presented obstacles almost insuperable, still many important points with regard to its manufacture have been elucidated. It has been found that the tin salt used in precipitating it must contain both the binoxide and protoxide of tin in certain proportions, and it has been also discovered that the degree of dilution both of the gold and tin solutions exerts a very perceptible influence on the beauty of the preparation. Capaun has examined this latter point with great attention, by testing all the different products as to their power of colouring glass.The first point to be attained is the preparation of a solution of sesquioxide of tin; and for this purpose Bolley proposes to employ the double compound of bichloride of tin with sal-ammoniac (pink salt). This salt is not altered by exposure to the atmosphere, and contains a fixed and known quantity of bichloride of tin, and when boiled with metallic tin it takes up so much as will form the protochloride; as the exact quantity of the bichloride is known, it is very easy to use exactly such a quantity of tin as will serve to form the sesquichloride. 100 parts of the pink salt require for this purpose 10·7 parts of metallic tin.Capaun recommends dissolving 1·34 gr. of gold in aqua regia, an excess being carefully avoided, and diluting the solution with 480 grs. of water. 10 grs. of pink salt are mixed with 1·07 gr. of tin filings and 40 grs. of water, and the whole boiled till the tin is dissolved. 140 grs. of water are then added to this, and the solution gradually mixed with the gold liquor, slightly warmed, until no more precipitation ensues. The precipitate washed and dried weighs 4·92 grs. and is of a dark brown colour.M. Figuier states, as the results of his investigations, that the purple of Cassius is a perfectly definite combination of protoxide of gold and of stannic acid, or peroxide of tin, the proof of which is, that it is instantly produced when protoxide of gold and peroxide of tin are placed in contact.]].

This Cassius, from whom it takes its name, was called Andrew, and because both the father and the son had the same christian name, they have been often confounded with each other. The father was secretary to the duke of Schleswig, and is not known as a man of letters; but the son is celebrated as the inventor or preparer of the gold-purple, and of a bezoar-essence. He took the degree of doctor at Leyden, in 1632, practised physic at Hamburg, and was appointed physician in ordinary to the bishop of Lubec. As far as I know, he never published anything respecting his art; but this service was rendered to the public by his son, who was born at Hamburg, and resided as a physician at Lubec. He was the author of a well-known treatise, now exceedingly scarce, entitled Thoughts concerning that last and most perfect work of nature, and chief of metals, gold, its wonderful properties, generation, affections, effects, and fitness for the operations of art; illustrated by experiments[316 - The original title runs thus: – De extremo illo et perfectissimo naturæ opificio ac principe terrenorum sidere, auro, et admiranda ejus natura, generatione, affectionibus, effectis, atque ad operationes artis habitudine, cogitata; experimentis illustrata. Hamburgi, 1685, 8vo.].

From this work, it will be easily understood why the author does not give himself out as the inventor of the gold-purple[317 - Joh. Molleri Cimbria Literata. Havniæ, 1774, fol. i. p. 88.], which he is commonly supposed to be, at which Lewis is much astonished. It is seen also by it that Leibnitz calls him improperly a physician at Hamburg, having probably confounded the father and son together[318 - Miscellanea Berolinensia, i. p. 94.]. Upon the whole, it is not proved that any of the Cassius’s was the inventor of the above precipitate, else it would certainly not have been omitted[319 - The author shows only, in a brief manner, in how many ways this precipitate can be used; but he makes no mention of employing it in colouring glass.] in this treatise; and mention of gold-purple is to be found in the works of several old chemists[320 - I cannot, however, affirm that the vasa murrhina of the ancients were a kind of porcelain coloured with this salt of gold. This is only a mere conjecture.].

Something of this kind has, doubtless, been meant by the old chemists, when they talk of red lions, the purple soul of gold, and the golden mantle; but what they wished to conceal under these metaphors, I am not able to conjecture. In the year 1606, when Libavius published his Alchemy, the art of making ruby-glass must have been unknown. He indeed quotes an old receipt for making rubies; and conjectures, that because the real stones of the same name are found in the neighbourhood of gold mines, they may have acquired their colour from that metal; and that by means of art, glass might be coloured by a solution of gold[321 - Alchymia Andr. Libavii. Franc. 1606, fol. ii. tract. i. c. 34.]. The later chemists, however, and particularly Achard, found no traces of gold, but of iron, in that precious stone[322 - See Gotting. Gel. Anzeigen, 1778, p. 177.].

Neri, who lived almost at the same time as Libavius[323 - It is well known that Neri’s works are translated into Kunkel’s Ars Vitraria, the edition of which, published at Nuremberg in 1743, I have in my possession. The time Neri lived is not mentioned in the Dictionary of Learned Men; but it appears, from the above edition of Kunkel, that he was at Florence in 1601, and at Antwerp in 1609. The oldest Italian edition of his works I have ever seen is L’arte vetraria – del R. R. Antonio Neri, Fiorentino. In Venetia, 1663. The first edition, however, must be older. [It is Florence, Giunti, 1612. – Ed.]], was better acquainted with the gold-purple, though his receipt is very defective. According to his directions, the gold solution must be evaporated, and the residue suffered to remain over the fire until it becomes of a purple colour. One may readily believe that this colour will be produced; but glass will scarcely be coloured equally through by this powder, and perhaps some of the gold particles will show themselves in it. Kunkel affirms, and not without reason, that something more is necessary to make rubies by means of gold; but he has not thought proper to tell us what it is[324 - Neri, b. vii. c. 129, pp. 157 and 174.].

Glauber, who wrote his Philosophical Furnace[325 - Amst. 1651, vol. iv. p. 78. Lewis says that Furnus Philosophicus was printed as early as 1648.] about the middle of the seventeenth century, appears to have made several experiments with the gold-purple. He dissolved the metal in aqua regia; precipitated it by liquor of flint, and melted into glass the precipitate, which contained in it abundance of vitreous earth[326 - Glauber first made known liquor of flint, and recommended it for several uses. See Ettmulleri Opera, Gen. 1736, 4 vol. fol. ii. p. 170.].

None, however, in the seventeenth century, understood better the use and preparation of gold-purple than John Kunkel, who, after being ennobled by Charles XI., king of Sweden, assumed the name of Löwenstiern. He himself tells us, that he made artificial rubies in great abundance, and sold them by weight, at a high price. He says, he made for the elector of Cologne a cup of ruby-glass, weighing not less than twenty-four pounds, which was a full inch in thickness, and of an equally beautiful colour throughout. He employed himself most on this art after he engaged in the service of Frederic William, elector of Brandenburg, in the year 1679. At that time he was inspector of the glass-houses at Potsdam; and, in order that the art of making ruby-glass might be brought to perfection, the elector expended 1600 ducats. A cup with a cover, of this manufacture, is still preserved at Berlin. Kunkel, however, has nowhere given a full account of this art. He has only left in his works a few scattered remarks, which Lewis has collected[327 - Lewis, Zusammenhang der Künste. Zür. 1764, 2 vols. 8vo, i. p. 279.].

In the year 1684, earlier than Cassius, John Christian Orschal wrote his well-known work, Sol sine veste[328 - The first edition was printed at Augsburg, in duodecimo, and the same year at Amsterdam. It has been often printed since, as in 1739, in 3 vols. 4to, without name or place.], in which he treats, more intelligibly than any one before him, of the manner of making ruby-glass. He, however, confesses that Cassius first taught him to precipitate gold by means of tin; that Cassius traded in glass coloured with this precipitate, and that a good deal of coloured glass was then made at Freysingen, but that the art was kept very secret. As Orschal deserves that his fate should be better known, I shall here mention the following few particulars respecting him. About the year 1682 he was at Dresden, in the service of John Henry Rudolf, from whom he learnt many chemical processes, and particularly amalgamation, by which he gained money afterwards in Bohemia. After this he was employed at the mines in Hesse; but he brought great trouble upon himself by polygamy and other irregularities, and died in a monastery in Poland.

Christopher Grummet, who was Kunkel’s assistant, wrote, in opposition to Orschal, his known treatise, Sol non sine veste, which was printed at Rothenburg, in 1685[329 - A French translation of Orschal and Grummet is added to l’Art de la Verrérie de Neri, Merret et Kunkel. Paris, 1752, 4to. The editor is the Baron de Holbach.]. In like manner, an anonymous author printed against Orschal, at Cologne, in 1684, another work, in duodecimo, entitled Apelles post tabulam observans maculas in Sole sine veste. The dispute, however, was not so much concerning the use of gold-purple, as the cause of the red colour, and the vitrification of gold.

It is worthy of remark, that Kunkel affirms he could give to glass a perfect ruby-red colour without gold; which Orschal and most chemists have however doubted. It is nevertheless said, that Krüger, who was inspector of the glass-houses at Potsdam, under Frederic William king of Prussia, discovered earlier the art of making ruby-glass without gold, and that a cup and cover of cut glass made in this manner is still preserved at Berlin.

Painting on glass and in enamel, and the preparation of coloured materials for mosaic work, may, in certain respects, be considered as branches of the art of colouring glass; and in all these a beautiful red is the most difficult, the dearest, and the scarcest. When the old master-pieces of painting on glass are examined, it is found either that the panes have on one side a transparent red varnish burnt into them, or that the pieces which are stained through and through, are thinner than those coloured in the other manner[330 - See Peter le Vieil’s Kunst auf Glas zu malen, Nuremberg, 1779, 4to, ii. p. 25. This singular performance must, in regard to history, particularly that of the ancients, be read with precaution. Seldom has the author perused the works which he quotes; sometimes one cannot find in them what he assures us he found, and very often he misrepresents their words.]. It is therefore extremely probable that the old artists, as they did not know how to give to thick pieces a beautiful transparent red colour, employed only iron, or manganese, which pigment, as already observed, easily becomes in a strong heat blackish and muddy[331 - In what the art of Abraham Helmback, a Nuremberg artist, consisted, I do not know. Doppelmayer, in his Account of the Mathematicians and Artists of Nuremberg, printed in 1730, says that he fortunately revived, in 1717, according to experiments made in a glass-house, the old red glass; the proper method of preparing which had been long lost.]. Enamel-painters, however, were for a long time obliged to be contented with it. A red colour in mosaic work is attended with less difficulty, because no transparency, nay rather opacity, is required. At Rome those pieces are valued most which have the beautiful shining red colour of the finest sealing-wax. We are told by Ferber that such pieces were at one time made only by a man named Mathioli, and out of a kind of copper dross; at present (1792), there are several artists in that city who prepare these materials, but they are not able to give them a perfect high colour[332 - Ferber’s Briefe aus Welschland. Prague, 1773, 8vo, p. 114.].

[Of late years the interesting art of painting on glass has attracted considerable attention; lovers of the fine arts, antiquaries, and chemists, have contributed to its perfection, and have sought to ascertain by what methods their predecessors were able to give those beautiful and brilliant tints to their productions, many of which have been so wantonly destroyed by the barbarity of the last century[333 - The devastations to which the productions of this beautiful art have been subjected are deeply to be regretted. It appears from the interesting Account of Durham Cathedral, published by the Rev. James Raine, that there was much fine stained glass in the fifteen windows of the Nine Altars which“shed their many-colour’d lightThrough the rich robes of eremites and saints;”until the year 1795, when “their richly painted glass and mullions were swept away, and the present plain windows inserted in their place. The glass lay for a long time afterwards in baskets on the floor; and when the greater part of it had been purloined the remainder was locked up in the Galilee.” And in 1802 a beautiful ancient structure, the Great Vestry, “was, for no apparent reason, demolished, and the richly painted glass which decorated its windows was either destroyed by the workmen or afterwards purloined.” The exquisite Galilee itself had been condemned, but was saved by a happy chance.]. One of the most ingenious essays that has been written on the subject, is that published by an anonymous correspondent in the Philosophical Magazine for December 1836, which we subjoin in elucidation of our present knowledge on the subject.

On the Art of Glass-Painting.By a Correspondent

It is a singular fact, that the art of glass-painting, practised with such success during the former ages from one end of Europe to the other, should gradually have fallen into such disuse, that in the beginning of the last century it came to be generally considered as a lost art. In the course of the eighteenth century, however, the art again began to attract attention, and many attempts were made to revive it. It was soon found by modern artists, that by employing the processes always in use among enamel-painters, the works of the old painters on glass might in most respects be successfully imitated; but they were totally unable to produce any imitation whatever of that glowing red which sheds such incomparable brilliancy over the ancient windows that still adorn so many of our churches[334 - In 1774 the French Academy published Le Vieil’s treatise on Glass-painting. He possessed no colour approaching to red, except the brick-red or rather rust-coloured enamel subsequently mentioned in the text, derived from iron.]. For this splendid colour they possessed no substitute, until a property, peculiar to silver alone among all the metals, was discovered, which will presently be described. The art of enamelling on glass differs little from the well-known art of enamelling on other substances. The colouring materials (which are exclusively metallic) are prepared by being ground up with a flux, that is, a very fusible glass, composed of silex, flint-glass, lead, and borax: the colour with its flux is then mixed with volatile oil, and laid on with the brush. The pane of glass thus enamelled is then exposed to a dull red heat, just sufficient to soften and unite together the particles of the flux, by which means the colour is perfectly fixed on the glass. Treated in this way, gold yields a purple, gold and silver mixed a rose-colour, iron a brick-red, cobalt a blue[335 - It appears by a boast of Suger, abbot of St. Denis, which has been preserved, that the ancient glass-painters pretended to employ sapphires among their materials; hence, perhaps, the origin of the term Zaffres, under which the oxide of cobalt is still known in commerce.]; mixtures of iron, copper and manganese, brown and black. Copper, which yields the green in common enamel-painting[336 - Oxide of chromium is now substituted for the copper.], is not found to produce a fine colour when applied in the same way to glass, and viewed by transmitted light; for a green therefore recourse is often had to glass coloured blue on one side and yellow on the other. To obtain a yellow, silver is employed, which, either in the metallic or in any other form, possesses the singular property of imparting a transparent stain, when exposed to a low red heat in contact with glass. This stain is either yellow, orange, or red, according to circumstances. For this purpose no flux is used: the prepared silver is merely ground up with ochre or clay, and applied in a thick layer upon the glass. When removed from the furnace the silver is found not at all adhering to the glass; it is easily scraped off, leaving a transparent stain, which penetrates to a certain depth. If a large proportion of ochre has been employed, the stain is yellow; if a small proportion, it is orange-coloured; and by repeated exposure to the fire, without any additional colouring matter, the orange may be converted into red. This conversion of orange into red is, I believe, a matter of much nicety, in which experience only can ensure success. Till within a few years this was the only bright red in use among modern glass-painters; and though the best specimens certainly produce a fine effect, yet it will seldom bear comparison with the red employed in such profusion by the old artists.

Besides the enamels and stains above-described, artists, whenever the subject will allow of it, make use of panes coloured throughout their substance in the glass-house melting-pot, because the perfect transparency of such glass gives a brilliancy of effect, which enamel-colouring, always more or less opake, cannot equal. It was to a glass of this kind that the old glass-painters owed their splendid red. This in fact is the only point in which the modern and ancient processes differ, and this is the only part of the art which was ever really lost. Instead of blowing plates of solid red, the old glass-makers used to flash a thin layer of red over a substratum of plain glass. Their process must have been to melt side by side in the glass-house a pot of plain and a pot of red glass: then the workman, by dipping his rod first into the plain and then into the red glass pot, obtained a lump of plain glass covered with a coating of red, which, by dexterous management in blowing and whirling, he extended into a plate, exhibiting on its surface a very thin stratum of the desired colour[337 - That such was the method in use, an attentive examination of old specimens affords sufficient evidence. One piece that I possess exhibits large bubbles in the midst of the red stratum; another consists of a stratum of red inclosed between two colourless strata: both circumstances plainly point out the only means by which such an arrangement could be produced.]. In this state the glass came into the hands of the glass-painter, and answered most of his purposes, except when the subject required the representation of white or other colours on a red ground: in this case it became necessary to employ a machine like the lapidary’s wheel, partially to grind away the coloured surface till the white substratum appeared.

The material employed by the old glass-makers to tinge their glass red was the protoxide of copper, but on the discontinuance of the art of glass-painting the dependent manufacture of red glass of course ceased, and all knowledge of the art became so entirely extinct, that the notion generally prevailed that the colour in question was derived from gold[338 - In 1793, the French government actually collected a quantity of old red glass, with the view of extracting the gold by which it was supposed to be coloured! Le Vieil was himself a glass-painter employed in the repair of ancient windows, and the descendant of glass-painters, yet so little was he aware of the true nature of the glass, that he even fancied he could detect the marks of the brush with which he imagined the red stratum had been laid on!]. It is not a little remarkable that the knowledge of the copper-red should have been so entirely lost, though printed receipts have always existed detailing the whole process. Baptista Porta (born about 1540) gives a receipt in his Magia Naturalis, noticing at the same time the difficulty of success. Several receipts are found in the compilations of Neri, Merret and Kunckel, from whence they have been copied into our Encyclopædias[339 - [M. Langlois names the following writers: “Neri en 1612, Handicquer de Blancourt en 1667, Kunkel en 1679, Le Vieil en 1774, et plusieurs autres écrivains à diverses époques, decrivaient ces procédés.” (p. 192.) He fixes the restoration of the art in France at about the year 1800, when Brongniart, who had the direction of the Sèvres porcelain manufacture, worked with Méraud at the preparation of vitrifiable colours, p. 194. Among modern artists he particularly mentions Dihl, Schilt, Mortelègue, Robert, Leclair, Collins, and Willement.]]. None of these receipts however state to what purposes the red glass was applied, nor do they make any mention of the flashing. The difficulty of the art consists in the proneness of the copper to pass from the state of protoxide into that of peroxide, in which latter state it tinges glass green. In order to preserve it in the state of protoxide, these receipts prescribe various deoxygenating substances to be stirred into the melted glass, such as smiths’ clinkers, tartar, soot, rotten wood, and cinnabar.

One curious circumstance deserves to be noticed, which is, that glass containing copper when removed from the melting-pot sometimes only exhibits a faint greenish tinge, yet in this state nothing more than simple exposure to a gentle heat is requisite to throw out a brilliant red. This change of colour is very remarkable, as it is obvious that no change of oxygenation can possibly take place during the recuisson.

The art of tinging glass by protoxide of copper and flashing it on crown-glass, has of late years been revived by the Tyne Company in England, at Choisy in France[340 - Bulletin de la Société d’Encouragement pour l’Industrie Nationale, 1826.], and in Suabia in Germany, and in 1827 the Academy of Arts at Berlin gave a premium for an imperfect receipt. To what extent modern glass-painters make use of these new glasses I am ignorant; the specimens that I have seen were so strongly coloured as to be in parts almost opake, but this is a defect which might no doubt be easily remedied[341 - Though it is difficult to produce the copper-glass uniformly coloured, it is easy to obtain streaks and patches of a fine transparent red. For this purpose it is sufficient to fuse together 100 parts of crown-glass with one of oxide of copper, putting a lump of tin into the bottom of the crucible. Metallic iron employed in the same way as the tin throws out a bright scarlet, but perfectly opake.].

I shall now conclude these observations by a few notices respecting glass tinged by fusion with gold, which, though never brought into general use among glass-painters, has I know been employed in one or two instances, flashed both on crown- and on flint-glass. Not long after the time when the art of making the copper-red glass was lost, Kunkel appears to have discovered that gold melted with flint-glass was capable of imparting to it a beautiful ruby colour. As he derived much profit from the invention, he kept his method secret, and his successors have done the same to the present day. The art, however, has been practised ever since for the purpose of imitating precious stones, &c., and the glass used to be sold at Birmingham for a high price under the name of Jew’s glass. The rose-coloured scent-bottles, &c., now commonly made, are composed of plain glass flashed or coated with a very thin layer of the glass in question. I have myself made numerous experiments on this subject, and have been completely, and at last uniformly, successful, in producing glass of a fine crimson colour. One cause why so many persons have failed in the same attempt[342 - “Dr. Lewis states that he once produced a potfull of glass of beautiful colour, yet was never able to succeed a second time, though he took infinite pains, and tried a multitude of experiments with that view.” Commerce of Arts, p. 177.], I suspect is that they have used too large a proportion of gold; for it is a fact, that an additional quantity of gold, beyond a certain point, far from deepening the colour, actually destroys it altogether. Another cause probably is, that they have not employed a sufficient degree of heat in the fusion. I have found that a degree of heat, which I judged sufficient to melt cast-iron, is not strong enough to injure the colour. It would appear, that in order to receive the colour, it is necessary that the glass should contain a proportion either of lead, or of some other metallic glass. I have found bismuth, zinc, and antimony to answer the purpose, but have in vain attempted to impart any tinge of this colour to crown-glass alone.

Glass containing gold exhibits the same singular change of colour on being exposed to a gentle heat, as has been already noticed with respect to glass containing copper[343 - [At the recent meeting of the British Association for the Advancement of Science, held at Cambridge (June 1845), M. Splittgerber exhibited specimens of glass into the composition of which gold entered as a chloride. These specimens were white, but upon gently heating them in the flame of a spirit-lamp, they became a deep-red. If again the same reddened glass is exposed to the heat of an oxygen blowpipe, it loses nearly all its colours, a slight pinkiness only remaining.]]. The former when taken from the crucible is generally of a pale rose-colour, but sometimes colourless as water, and does not assume its ruby colour till it has been exposed to a low red-heat, either under a muffle or in the lamp. Great care must be taken in this operation, for a slight excess of fire destroys the colour, leaving the glass of a dingy brown, but with a blue transparency like that of gold-leaf. These changes of colour have been vaguely attributed to change of oxygenation in the gold; but it is obviously impossible that mere exposure to a gentle heat can effect any chemical change in the interior of a solid mass of glass, which has already undergone a heat far more intense. In fact I have found that metallic gold gives the red colour as well as the oxide, and it appears scarcely to admit of a doubt, that in a metal so easily reduced, the whole of the oxygen must be expelled long before the glass has reached its melting-point. It has long been known that silver yields its colour to glass while in the metallic state, and everything leads one to suppose that the case is the same as to gold.

There is still one other substance by means of which I find it is possible to give a red colour to glass, and that is a compound of tin, chromic acid, and lime; but my trials do not lead me to suppose that glass thus coloured will ever be brought into use.

* * * * *

With respect to the production of artificial gems, they are now made abundantly of almost every shade of colour, closely approximating to those which occur in nature, excepting in hardness and refractive power. They are formed by fusing what is called a base with various metallic oxides. The base varies in composition: thus, M. Fontanieu makes his by fusing silica with carbonate of potash, carbonate of lead and borax. M. Donault Wieland’s consists of silica, potash, borax, oxide of lead, and sometimes arsenious acid. Hence the base differs but little in composition from glass. By fusing the base with metallic oxides, the former acquires various tints. Thus with oxide of antimony the oriental topaz is prepared; with oxide of manganese and a little purple of cassius, the amethyst; with antimony and a very small quantity of cobalt, the beryl; with horn silver (chloride of silver), the diamond and opal: the oriental ruby is prepared from the base, the purple of cassius, peroxide of iron, golden sulphuret of antimony, manganese calcined with nitre and rock crystal.]

SEALING-WAX

Writers on diplomatics mention, besides metals, five other substances on which impressions were made, or with which letters and public acts were sealed, viz. terra sigillaris, cement, paste, common wax, and sealing-wax[344 - Gattereri Elem. Artis Diplom. 1765, 4to, p. 285.]. The terra sigillaris was used by the Egyptians, and appears to have been the first substance employed for sealing[345 - It is singular that Pliny denies that the Egyptians used seals, lib. xxiii. c. 1. Herodotus however, and others, prove the contrary; and Moses speaks of the seal-rings of the Egyptians. See Goguet.]. The Egyptian priests bound to the horns of the cattle fit for sacrifice a piece of paper; stuck upon it some sealing-earth, on which they made an impression with their seal; and such cattle only could be offered up as victims[346 - Herodot. lib. ii. c. 38.].

Lucian speaks of a fortune-teller who ordered those who came to consult him to write down on a bit of paper the questions they wished to ask, to fold it up, and to seal it with clay, or any other substance of the like kind[347 - Lucian. in Pseudomant.]. Such earth seems to have been employed in sealing by the Byzantine emperors: for we are told that at the second council of Nice, a certain person defended the worship of images by saying, no one believed that those who received written orders from the emperor and venerated the seal, worshiped on that account the sealing-earth, the paper, or the lead[348 - Act. iv. ap. Bin. tom. iii. Concil. part. i. p. 356. Whether the γῆ σημαντρὶς, however, of Herodotus and the πηλὸς of Lucian and of the Byzantine be the same kind of earth, can be determined with as little certainty as whether the creta, called by some Roman authors a sealing-earth, be different from both.].

Cicero relates that Verres having seen in the hands of one of his servants a letter written to him from Agrigentum, and having observed on it an impression in sealing-earth (cretula), he was so pleased with it that he caused the seal-ring with which it was made to be taken from the possessor[349 - Orat. in Verrem, iv. c. 9. In the passage referred to, some instead of cretula read cerula. I shall here take occasion to remark also, that in the Acts of the Council of Nice before-mentioned, instead of πηλὸν some read κηρόν: but I do not see a sufficient reason for this alteration, as in the before-quoted passage of Lucian it is expressly said, that people sealed κηρῷ ἣ πηλῷ. Reiske himself, who proposes that amendment, says that πηλὸν may be retained. Stephanus, however, does not give that meaning to this word in his Lexicon. Pollux and Hesychius tell us, that the Athenians called sealing-earth also ῥύπον.]. The same orator, in his defence of Flaccus, produced an attestation sent from Asia, and proved its authenticity by its being sealed with Asiatic sealing-earth; with which, said he to the auditors, as you daily see, all public and private letters in Asia are sealed: and he showed on the other hand that the testimony brought by the accuser was false, because it was sealed with wax, and for that reason could not have come from Asia[350 - Orat. pro Flacco, c. 16.]. The scholiast Servius relates, that a sibyl received a promise from Apollo, that she should live as long as she did not see the earth of the island Erythræa where she resided; that she therefore quitted the place, and retired to Cumæ, where she became old and decrepid; but that having received a letter sealed with Erythræan earth (creta), when she saw the seal she instantly expired[351 - Serv. ad lib. vi. Æneid. p. 1037.].

No one however will suppose that this earth was the same as that to which we at present give the name of creta, chalk; for if it was a natural earth it must have been of that kind called potters’ clay, as that clay is capable of receiving an impression and of retaining it after it is hardened by drying. That the Romans, under the indefinite name of creta, often understood a kind of potters’ earth, can be proved by many passages of their writers. Columella speaks of a kind of chalk of which wine-jars and dishes were made[352 - Lib. xii. c. 43.]. Virgil calls it tough[353 - Georg. i. v. 179.]; and the ancient writers on agriculture give the same name to marl which was employed to manure land[354 - Creta fossica, qua stercorantur agri. – Varro, i. 7. 8. It appears also that the πηλὸς of the Greeks signified a kind of potters’ earth. Those who do not choose to rely upon our dictionaries, need only to read the ancient Greek writers on husbandry, who speak of ἀῤῥαγεῖ πηλῷ ἀργιλλώδει. See Geopon. x. c. 75. 12, and ix. c. 10. 4.]. Notwithstanding all these authorities, I do not clearly comprehend how letters could be sealed with potters’ clay, as it does not adhere with sufficient force either to linen, of which in ancient times the covers of letters were made, or to parchment; as it must be laid on very thick to have a distinct impression; as it is long in drying, and is again easily softened by moisture; and, at any rate, if conveyed by post at present, it would be crumbled into dust in going only from Hamburg to Altona. I can readily believe that the Roman messengers employed more skill and attention to preserve the letters committed to their care than are employed by our postmen; but the distance from Asia to Rome is much greater than that from Hamburg to Altona.

But may there not be as little foundation for the ancient expression creta Asiatica, Asiatic earth, as for the modern expression, cera Hispanica, Spanish wax? May not the former have signified a kind of coarse artificial cement? These questions might be answered by those who have had an opportunity of examining or only seeing the sigilla cretacea in collections of antiquities. We are assured that such are still preserved; at least we find in Ficoroni[355 - I piombi antichi. Roma 1740, 4to, p. 16.] the representation of six impressions which, as he tells us, consisted of that earth. In that author however I find nothing to clear up my doubts; he says only that some of these seals were white; others of a gray colour, like ashes; others red, and others brown. They seem all to have been enclosed in leaden cases. Could it be proved that each letter was wrapped round with a thread, and that the thread, as in the seals affixed to diplomas, was drawn through the covering of the seal, the difficulty which I think occurs in the use of these earths, as mentioned by the ancients, would entirely disappear[356 - Heineccius and others think that the amphoræ vitreæ diligenter gypsatæ, in Petronius, were sealed; but it is much more probable that they were only daubed over or closed with gypsum, for the same reason that we pitch our casks.]. It seems to me remarkable that neither Theophrastus nor Pliny says anything of the Asiatic creta, or speaks at all of sealing-earth; though they have carefully enumerated all those kinds of earth which were worth notice on account of any use.

In Europe, as far as I know, wax has been everywhere used for sealing since the earliest ages. Writers on diplomatics, however, are not agreed whether yellow or white wax was first employed; but it appears that the former, on account of its low price, must have been first and principally used, at least by private persons. It is probable also, that the seals of diplomas were more durable when they consisted of yellow wax; for it is certain that white wax is rendered more brittle and much less durable by the process of bleaching. Many seals also may at present be considered white which were at first yellow; for not only does wax highly bleached resume in time a dirty yellow colour, but yellow wax also in the course of years loses so much of its colour as to become almost like white wax. This perhaps may account for the oldest seals appearing to be of white, and the more modern of yellow wax. These however are conjectures which I submit with deference to the determination of those versed in diplomatics.

In the course of time wax was coloured red; and a good deal later, at least in Germany, but not before the fourteenth century, it was coloured green, and sometimes black. I find it remarked that blue wax never appears on diplomas; and I may indeed say it is impossible it should appear, for the art of giving a blue colour to wax has never yet been discovered; and in old books, such as that of Wecker, we find no receipt for that purpose. Later authors have pretended to give directions how to communicate that colour to wax, but they are altogether false; for vegetable dyes when united with wax become greenish, so that the wax almost resembles the hip-stone; and earthy colours do not combine with it, but in melting fall again to the bottom. A seal of blue wax, not coloured blue merely on the outer surface, would be as great a rarity in the arts as in diplomatics, and would afford matter of speculation for our chemists; but I can give them no hopes that such a thing can ever be produced[357 - [Blue wax may now be seen in every wax-chandler’s shop; it is coloured blue by means of indigo.]]. The emperor Charles V. in the year 1524 granted to Dr. Stockamar of Nuremberg, the privilege of using blue wax in seals; – a favour like that conferred in 1704 on the manufactories in the principality of Halberstadt and the county of Reinstein, to make indigo from minerals. It was certainly as difficult for the doctor to find blue wax for seals as for the proprietors of these manufactories to discover indigo in the earth[358 - Heineccii Syntagma de Vet. Sigillis, 1719, p. 55.].

Much later are impressions made on paste or dough, which perhaps could not be employed on the ancient parchment or the linen covers of letters, though in Pliny’s time the paper then in use was joined together with flour paste[359 - Plin. lib. xxii. c. 25.]. Proper diplomas were never sealed with wafers; and in the matchless diplomatic collection of H. Gatterer there are no wafer-seals much above two hundred years old. From that collection I have now in my possession one of these seals, around the impression of which is the following inscription, Secretum civium in Ulma, 1474; but it is only a new copy of a very old impression. Kings, however, before the invention of sealing-wax, were accustomed to seal their letters with this paste[360 - Trotz, Not. in Prim. Scribendi Origine, p. 73, 74.].

Heineccius and others relate that maltha also was employed for seals. This word signifies a kind of cement, formed chiefly of inflammable substances, and used to make reservoirs, pipes, &c. water-tight. Directions how to prepare it may be found in the writers on agriculture, Pliny, Festus and others. The latter tells how to make it of a composition of pitch and wax[361 - P. Festi de Verb. Sig. lib. xx. Hesychius calls this cement μεμαλάγμενον κηρόν. – Plin. lib. xxxvi. c. 24.]: but neither in that author nor in any other have I found proofs that letters were sealed with it, or that seals of it were affixed to diplomas: for the words of Pollux, “cera qua tabella judicum obliniebatur[362 - Lib. viii. c. 4.],” will admit of a different explanation. If maltha has been in reality used for seals, that mixture may be considered as the first or oldest sealing-wax, as what of it is still preserved has been composed of resinous substances.

Some writers assert[363 - Nouveau Traité de Diplomatique. Paris, 1759, 4to, iv. p. 33.], upon the authority of Lebeuf[364 - Mémoires conc. l’Histoire d’Auxerre. Par. 1743, ii. p. 517.], that sealing-wax was invented about the year 1640 by a Frenchman named Rousseau; but that author refers his readers to Papillon[365 - Bibliothèque des Auteurs de Bourgogne, 2 vols. fol. ii. p. 217.], who refers again to Pomet[366 - Histoire Générale des Drogues. Paris, 1735.], so that the last appears to be the first person who broached that opinion. According to his account, Francis Rousseau, born not far from Auxerre, and who travelled a long time in Persia, Pegu and other parts of the East Indies, and in 1692 resided in St. Domingo, was the inventor of sealing-wax. Having, while he lived at Paris as a merchant, during the latter years of the reign of Louis XIII., who died in 1643, lost all his property by a fire, he bethought himself of preparing sealing-wax from shell-lac, as he had seen it prepared in India, in order to maintain his wife and five children. A lady of the name of Longueville made this wax known at court, and caused Louis XIII. to use it, after which it was purchased and used throughout all Paris. By this article, Rousseau, before the expiration of a year, gained 50,000 livres. It acquired the name of cire d’Espagne, Spanish wax, because at that time a kind of lac, which was only once melted and coloured a little red, was called Portugal wax, cire de Portugal[367 - This Rousseau appears also in the History of Cochineal, as he sent to Pomet a paper on that subject, which was contradicted by the well-known Plumier in the Journal des Sçavans for 1694. He is mentioned also by Labat, who says he saw him at Rochelle; but at that time he must have been nearly a hundred years of age.].

That sealing-wax was either very little or not at all known in Germany in the beginning of the sixteenth century, may be concluded from its not being mentioned either by Porta or Wecker; though in the works of both these authors there are various receipts respecting common wax, and little known methods of writing and sealing[368 - Von Murr, in his learned Beschreibung der Merkwürdigkeiten in Nürnberg, Nurnb. 1778, 8vo, p. 702, says that Spanish wax was not invented, or at least not known, before the year 1559. This appears also from a manuscript of the same year, which contains various receipts in the arts and medicine. There are some in it for making the common white sealing-wax green or red.]. The former says, that to open letters in such a manner as not to be perceived, the wax seal must be heated a little, and must be then carefully separated from the letter by a horse’s hair; and when the letter has been read and folded up, the seal must be again dexterously fastened to it. This manœuvre, as the writers on diplomatics remark, has been often made use of to forge public acts; and they have therefore given directions how to discover such frauds[369 - See Chronicon Godvicense, p. 102.]. The above method of opening letters, however, can be applied only to common wax, and not to sealing-wax: had the latter been used in Wecker’s time he would have mentioned this limitation[370 - Wecker gives directions also to make an impression with calcined gypsum, and a solution of gum or isinglass. Porta knew that this could be done to greater perfection with amalgam of quicksilver; an art employed even at present.].

Whether sealing-wax was used earlier in the East Indies than in Europe, as the French think, I cannot with certainty determine. Tavernier[371 - Tavernier, in his Travels, says that in Surat lac is melted and formed into sticks like sealing-wax. Compare with this Dapper’s Asia, Nuremberg, 1681, fol. p. 237.], however, seems to say that the lac produced in the kingdom of Assam is employed there not only for lackering, but also for making Spanish sealing-wax. I must confess also that I do not know whether the Turks and other eastern nations use it in general. In the collection of natural curiosities belonging to our university there are two sticks of sealing-wax which Professor Butner procured from Constantinople, under the name of Turkish wax. They are angular, bent like a bow, are neither stamped nor glazed, and are of a dark but pure red colour. Two other sticks which came from the East Indies are straight, glazed, made somewhat thin at both ends, have no stamp, and are of a darker and dirtier red colour. All these four sticks seem to be lighter than ours, and I perceive that by rubbing they do not acquire so soon nor so strong an electrical quality as our German wax of moderate fineness. But whether the first were made in Turkey and the latter in the East Indies, or whether the whole four were made in Europe, is not known. That sealing-wax however was made and used in Germany a hundred years before Rousseau’s time, and that the merit of that Frenchman consisted probably only in this, that he first made it in France, or made the first good wax, will appear in the course of what follows.

The oldest known seal of our common sealing-wax is that found by M. Roos, on a letter written from London, Aug. 3rd, 1554, to the rheingrave Philip Francis von Daun, by his agent in England, Gerrard Hermann[372 - Bruchstücke betreffend die Pflichten eines Staatsdieners; aus den Handlungen des Raths Dreitz, nebst Bemerkungen vom ältesten Gebrauche des Spanischen Siegelwachses, Frankf. 1785, 4to, p. 86; where the use of these antiquarian researches is illustrated by examples worthy of notice.]. The colour of the wax is a dark-red; it is very shining, and the impression bears the initials of the writer’s name G. H. The next seal, in the order of time, is one of the year 1561, on a letter written to the council of Gorlitz at Breslau. This letter was found among the ancient records of Gorlitz by Dr. Anton, and is three times sealed with beautiful red wax[373 - Historische Untersuchungen gesammelt von J. G. Meusel, i. 3, p. 240.]. Among the archives of the before-mentioned family M. Roos found two other letters of the year 1566, both addressed to the rheingrave Frederick von Daun, from Orchamp in Picardy, by his steward Charles de Pousol; the one dated September the 2nd, and the other September the 7th. Another letter, written by the same person to the same rheingrave, but dated Paris January 22nd, 1567, is likewise sealed with red wax, which is of a higher colour, and appears to be of a coarser quality. As the oldest seals of this kind came from France and England, M. Roos conjectures that the invention, as the name seems to indicate, belongs to the Spaniards. This conjecture appears to me however improbable, especially as sealing-wax was used at Breslau so early as 1561; but this matter can be best determined perhaps by the Spanish literati. It is much to be lamented that John Fenn, in his Original letters of the last half of the fifteenth century[374 - Original Letters of the Paston Family, temp. Henry VI. i. p. 21, and p. 87 and 92.], when he gives an account of the size and shape of the seals, does not inform us of what substances they are composed. Respecting a letter of the year 1455, he says only, “The seal is of red wax;” by which is to be understood, undoubtedly, common wax.

Among the records of the landgraviate of Cassel, M. Ledderhose found two letters of Count Louis of Nassau to the landgrave William IV., one of which, dated March the 3rd, 1563, is sealed with red wax, and the other, dated November 7th, the same year, is sealed with black wax[375 - Meusel’s Geschichtforscher. Halle, 8vo, vi. p. 270.]. M. Neuberger, private keeper of the archives at Weimar, found among the records of that duchy a letter sealed with red wax, and written at Paris, May the 15th, 1571, by a French nobleman named Vulcob, who the year before had been ambassador from the king of France to the court of Weimar. It is worthy of remark, that the same person had sealed nine letters of a prior date with common wax, and that the tenth is sealed with Spanish wax. P. L. Spiess, principal keeper of the records at Plessenburg, who gave rise to this research by his queries, saw a letter of the year 1574 sealed with red sealing-wax, and another of the year 1620 sealed with black sealing-wax. He found also in an old expense-book of 1616, that Spanish wax, expressly, and other materials for writing were ordered from a manufacturer of sealing-wax at Nuremberg, for the personal use of Christian margrave of Brandenburg[376 - Ibid. iv. p. 251.].

The oldest mention of sealing-wax which I have hitherto observed in printed books is in the work of Garcia ab Orto[377 - Aromatum et Simplicium aliquot Historia, Garcia ab Horto auctore. Antverpiæ 1574, 8vo, p. 33.], where the author remarks, speaking of lac, that those sticks used for sealing letters were made of it. This book was first printed in 1563, about which time it appears that the use of sealing-wax was very common among the Portuguese.

The oldest printed receipt for making sealing-wax was found by Von Murr, in a work by Samuel Zimmerman, citizen of Augsburg, printed in 1579[378 - Neu Titularbuch, – sambt etlichen hinzugethanen Gehaimnüssen und Künsten, das Lesen und die Schreiberey betreffendt. 4to, 1579, p. 112.]. The copy which I have from the library of our university is signed at the end by the author himself. His receipts for making red and green sealing-wax I shall here transcribe.

“To make hard sealing-wax, called Spanish wax, with which if letters be sealed they cannot be opened without breaking the seal: – Take beautiful clear resin, the whitest you can procure, and melt it over a slow coal fire. When it is properly melted, take it from the fire, and for every pound of resin add two ounces of vermilion pounded very fine, stirring it about. Then let the whole cool, or pour it into cold water. Thus you will have beautiful red sealing-wax.

“If you are desirous of having black wax, add lamp-black to it. With smalt or azure you may make it blue; with white-lead white, and with orpiment yellow.

“If instead of resin you melt purified turpentine in a glass vessel, and give it any colour you choose, you will have a harder kind of sealing-wax, and not so brittle as the former.”

What appears to me worthy of remark in these receipts for sealing-wax is, that there is no mention in them of shell-lac, which at present is the principal ingredient, at least in that of the best quality; and that Zimmerman’s sealing-wax approaches very near to that which in diplomatics is called maltha. One may also conclude therefore that this invention was not brought from the East Indies.

The expression Spanish wax is of little more import than the words Spanish-green, Spanish-flies, Spanish-grass, Spanish-reed, and several others, as it was formerly customary to give to all new things, particularly those which excited wonder, the appellation of Spanish; and in the like manner many foreign or new articles have been called Turkish; such as Turkish wheat, Turkish paper, &c.

Respecting the antiquity of wafers, M. Spiess has made an observation[379 - Archivische Nebenarbeiten und Nachrichten. Halle, 1785, 4to, ii. p. 3.] which may lead to further researches, that the oldest seal with a red wafer he has ever yet found, is on a letter written by D. Krapf at Spires in the year 1624, to the government at Bayreuth. M. Spiess has found also that some years after, Forstenhäusser, the Brandenburg factor at Nuremberg, sent such wafers to a bailiff at Osternohe. It appears however that wafers were not used during the whole of the seventeenth century in the chancery of Brandenburg, but only by private persons, and by these even seldom; because, as Spiess says, people were fonder of Spanish wax. The first wafers with which the chancery of Bayreuth began to make seals were, according to an expense account of the year 1705, sent from Nuremberg. The use of wax however was still continued; and among the Plassenburg archives there is a rescript of 1722, sealed with proper wax. The use of wax must have been continued longer in the duchy of Weimar; for in the Electa Juris Publici there is an order of the year 1716, by which the introduction of wafers in law matters is forbidden, and the use of wax commanded. This order however was abolished by duke Ernest Augustus in 1742, and wafers again introduced.

CORN-MILLS

If under this name we comprehend all those machines, however rude, employed for pounding or grinding corn, these are of the highest antiquity. We read in the Scriptures, that Abraham caused cakes to be baked for his guests of the finest meal; and that the manna was ground like corn. The earliest instrument used for this purpose seems to have been the mortar; which was retained a long time even after the invention of mills properly so called, because these perhaps at first were not attended with much superior advantage[380 - Hesiod, Opera et Dies, 421. – It appears that both the mortar and pestle were then made of wood, and that the former was three feet in height; but, to speak the truth, Hesiod does not expressly say that this mortar was for the purpose of pounding corn. The mortar was called ὕπερος, pila; the pestle ὕπερος, or ὕπερον, pistillus or pistillum; to pound, μάσσειν, pinsere, which word, as well as pinsor, was afterwards retained when mills came to be used. – Plin. lib. xviii. c. 3.]. It appears that in the course of time the mortar was made rigid and the pestle notched, at least at the bottom; by which means the grain was rather grated than pounded. A passage of Pliny[381 - Plin. xviii. 10. ii. p. 111. This passage Gesner has endeavoured to explain, in his Index to the Scriptores Rei Rusticæ, p. 59, to which he gives the too-dignified title of Lexicon Rusticum.], not yet sufficiently cleared up, makes this conjecture probable. When a handle was added to the top of the pestle, that it might be more easily driven round in a circle, the mortar was converted into a hand-mill. Such a mill was called mola trusatilis, versatilis, manuaria[382 - Gellius, iii. c. 3.], and was very little different from those used at present by apothecaries, painters, potters and other artists, for grinding coarse bodies, such as colours, glass, chalk, &c. We have reason to suppose that in every family there was a mill of this kind. Moses forbade them to be taken in pawn; for that, says he, is the same thing as to take a man’s life to pledge. Michaelis, on this passage, observes that a man could not then grind, and consequently could not bake bread for the daily use of his family[383 - Deuteronomy, ch. xxiv. v. 6.]. Grinding was at first the employment of the women, and particularly of the female slaves, as it is at present among uncivilised nations, and must therefore have required little strength[384 - When Moses threatened Pharaoh with the destruction of the first-born in the land of Egypt, he said, “All the first-born shall die, from the first-born of Pharaoh that sitteth on the throne, even unto the first-born of the maid-servant that is behind the mill.” – Genesis, ch. xi. v. 5. See Homeri Odyss. vii. 103, and xx. 105.]; but afterwards the mills were driven by bondsmen, around whose necks was placed a circular machine of wood, so that these poor wretches could not put their hands to their mouths, or eat of the meal.

In the course of time shafts were added to the mill that it might be driven by cattle, which were, as at present, blindfolded[385 - Apuleii Metamorph. lib. ix.]. The first cattle-mills, molæ jumentariæ, had perhaps only a heavy pestle like the hand-mills[386 - The oldest cattle-mills have, in my opinion, resembled the oil-mills represented in plate 25th of Sonnerat, Voyages aux Indes, &c., i. Zurich, 1783, 4to. To the pestle of a mortar made fast to a stake driven into the earth, is affixed a shaft to which two oxen are yoked. The oxen are driven by a man, and another stands at the mortar to push the seed under the pestle. Sonnerat says, that with an Indian hand-mill two men can grind no more than sixty pounds of meal in a day; while one of our mills, under the direction of one man, can grind more than a thousand.]; but it must have been soon remarked that the labour would be more speedily accomplished if, instead of the pestle, a large heavy cylindrical stone should be employed. I am of opinion, however, that the first cattle-mills had not a spout or a trough as ours have at present; at least the hand-mills which Tournefort[387 - Voyage du Lévant, 4to, p. 155.] saw at Nicaria, and which consisted of two stones, had neither; but the meal which issued from between the stones, through an opening made in the upper one, fell upon a board or table, on which the lower stone, that was two feet in diameter, rested.

The upper mill-stone was called meta, or turbo; and the lower one catillus. Meta signified also a cone with a blunt apex[388 - A haycock was called meta fœni. Colum. ii. 19. Plin. xxvii. 28.]; and it has on that account been conjectured that corn was at first rubbed into meal by rolling over it a conical stone flatted at the end, in the same manner as painters at present make use of a grinding-stone; and it is believed that the same name was afterwards given to the upper mill-stone. This conjecture is not improbable, as some rude nations still bruise their corn by grinding-stones. I do not, however, remember any passage in the ancients that mentions this mode of grinding; and I am of opinion, that the pestle of the hand-mill, for which the upper mill-stone was substituted, may, on account of its figure, have been also called meta. Niebuhr[389 - Niebuhr’s Déscription de l’Arabie. A figure of both stones is represented in the first plate, fig. H.] found in Arabia, besides hand-mills, some grinding-stones, which differed from those used by us in their consisting not of a flat, but of an oblong hollow stone, or trough, with a pestle, which was not conical, but shaped like a spindle, thick in the middle and pointed at both ends. In this stone the corn, after being soaked in water, was ground to meal and then baked into cakes.