Chapter V: Part 5

[139] Historia Vitri apud Judæos, in Comment. Societat. Scient. Gotting. iv. p. 330. Having requested Professor Tychsen’s opinion on this subject, I received the following answer:--“You have conjectured very properly that the mirrors of the Israelitish women, mentioned Exod. xxxviii. 8, were not employed for ornamenting or covering the washing-basins, in order that the priests might behold themselves in them; but that they were melted and basins cast of them. The former was a conceit first advanced, if I am not mistaken, by Nicol. de Lyra, in the fourteenth century, and which Michaelis himself adopted in the year 1754; but he afterwards retracted his opinion when he made his translation of the Old Testament at a riper age. In the Hebrew expression there is no ground for it; and mirrors could hardly be placed very conveniently in a basin employed for washing the feet. I must at the same time confess that the word (מראת) which is here supposed to signify a mirror, occurs nowhere else in that sense. Another explanation therefore has been given, by which both the women and mirrors disappear from the passage. It is by a learned Fleming, Hermann Gid. Clement, and may be found in his Dissertatio de Labro Æneo, Groning. 1732, and also in Ugolini Thesaurus, tom. xix. p. 1505. He translates the passage thus: Fecit labrum æneum et operculum ejus æneum cum _figuris ornantibus_, quæ ornabant ostium tabernaculi. This explanation however is attended with very great difficulties; and as all the old translators and Jewish commentators have here understood mirrors; and as the common translation is perfectly agreeable to the language and circumstances, we ought to believe that Moses, not having copper, melted down the mirrors of his countrywomen and converted them into washing-basins for the priests.”

[140] Oneirocrit. lib. iii. cap. 30. p. 176.

[141] Joh. Sarisberiensis, i. cap. 12.

[142] Plin. lib. xxxiii. cap. 9. Seneca, Quæst. Nat. i. cap. 5.

[143] Vita Probi, cap. iv. p. 926: “Patinam argenteam librarum decem specillatam.” Salmasius chooses rather to read _specellatam_. I am inclined to think that this word ought to be read in Suetonius instead of _speculatum_, where he speaks of an apartment which Horace seems to have been fond of. That historian, in his Life of Horace, says, “Ad res venereas intemperantior traditur: nam _speculato_ cubiculo scorta dicitur habuisse disposita, ut quocunque respexisset, ibi ei imago coitus referretur.” Lessing, who in his Miscellanies (Vermischten Schriften, Berlin 1784, 12mo, iii. p. 205) endeavours to vindicate the poet from this aspersion, considers the expression _speculatum cubiculum_, if translated _an apartment lined with mirrors_, as contrary to the Latin idiom, and thinks therefore that the whole passage is a forgery. Baxter also before said that this anecdote had been inserted by some malicious impostor. This I will not venture to contradict, but I am of opinion that _specillatum_ or _specellatum cubiculum_ is at any rate as much agreeable to the Roman idiom as _patina specillata_. This expression Salmasius and Casaubon have justified by similar phrases, such as _opera filicata_, _tesselata_, _hederata_, &c. The chamber in which Claudian makes Venus ornament herself, and be overcome by the persuasion of Cupid, was also covered over with mirrors, so that whichever way her eyes turned, she could see her own image. Did Claudian imagine that this goddess knew how to employ such an apartment, not only for dressing, but even after she was undressed, as well as Horace? I have seen at a certain court, a bed entirely covered in the inside with mirrors.

[144] Iliad. lib. xiv. ver. 166.

[145] Hymnus in Lavacrum Palladis, v. 15, 21. It was however customary to ascribe a mirror to Juno, as Spanheim on this passage proves; and Athanasius, in Orat. contra Gentes, cap. xviii. p. 18, says that she was considered as the inventress of dress and all ornaments. Should not therefore the mirror, the principal instrument of dress, belong to her? May it not have been denied to her by Callimachus, because he did not find it mentioned in the description which Homer has given of her dressing-room?

[146] De Natur. Deorum, iii. 22.

[147] Licetus de Lucernis Antiq. lib. vi. cap. 92.

[148] Lib. xxxiv. cap. 17, p. 669.

[149] Quæst. Nat. at the end of the first book.

[150] Mostell. act i. sc. 3. v. 101.

[151] Arrianus in Epictet. i. cap. 20, p. 79.

[152] Among the remaining passages of the ancients with which I am acquainted, in which mention is made of silver mirrors, the following deserves notice. Chrysostom, Serm. xvii. p. 224, who, in drawing a picture of the extravagance of the women, says, “The maid-servants must be continually importuning the silversmith to know whether their lady’s mirror be yet ready.” The best mirrors therefore were made by the silversmiths. It appears that the mirror-makers at Rome formed a particular company; at least Muratori, in Thesaur. Inscript. Clas. vii. p. 529, has made known an inscription in which _collegium speculariorum_ is mentioned. They occur also in Codex Theodos. xiii. tit. 4, 2. p. 57, where Ritter has quoted more passages in which they may be found. But perhaps the same name was given to those who covered walls with polished stones, and in latter times to glaziers.

[153] Lib. xxxiii. c. 9. p. 627, and lib. xxxiv. c. 17, p. 669.

[154] Philosophical Transactions, vol. lxvii. p. 296.

[155] Quomodo Historia sit conscrib. cap. 51, Bipont edition, iv. p. 210, 535. Commentators have found no other way to explain κέντρον (a word which occurs in Lucian’s description of the mirror), than by the word _centre_, to which, according to their own account, there can be here no allusion. In my opinion κέντρον signifies those faulty places which are not capable of a complete polish, on account of the knots or cracks which are found in them. Lucian therefore speaks of a faultless mirror which represents the image perfect, as he afterwards informs us.

[156] As the account of these experiments is given only in an expensive work, which may not often fall into the hands of those who are best able to examine it, I insert it here. “The ancient mirror, which I examined, was a metallic mixture, very tender and brittle, and of a whitish colour inclining to grey. When put into the fire, it remained a long time in a state of ignition before it melted. It was neither inflammable nor emitted any smell like garlic, which would have been the case had it contained arsenic. It did not either produce those flowers which are generally produced by all mixtures in which there is zinc. Besides, the basis of this mixture being copper, it would have been of a yellow colour had that semi-metal formed a part of it. I took two drams of it and dissolved them in the nitrous acid. A solution was speedily formed, which assumed the same colour as solutions of copper. It precipitated a white powder, which I carefully edulcorated and dried. Having put it into a crucible with a reductive flux, I obtained lead very soft and malleable.

“Having filtered the solution, I took a part of it, upon which I poured an infusion of gall-nuts, but it produced no change. A solution of gold, which I poured upon another part, made it assume a beautiful green colour; but no precipitate was formed: which is sufficient to prove that there was neither iron nor tin in the mixture.

“On the remaining part of the solution I poured a sufficient quantity of the volatile alkali to dissolve all the copper that might be contained in it. The solution became of a beautiful sapphire blue colour, and a white precipitate was formed. Having decanted the liquor, and carefully edulcorated the precipitate, I endeavoured to reduce it; but whether it was owing to the quantity being too small, or to my not giving it sufficient heat, I could not succeed. I had recourse therefore to another method.

“I took the weight of two drams of the mixture, which I brought to a high state of ignition in a cuppel. When it was of a whitish-red colour, I threw upon it gradually four drams of sulphur, and when the flame ceased, I strengthened the fire in order to bring it to complete fusion. By these means I obtained a tender brittle regulus, whiter than the mixture, in which I observed a few small needles. Being apprehensive that some copper might still remain, I sulphurated it a second time, and then obtained a small regulus which was almost pure antimony.

“It results from these experiments, that the metal of which the ancients made their mirrors was a composition of copper, regulus of antimony, and lead. Copper was the predominant, and lead the smallest part of the mixture; but it is very difficult, as is well known, to determine with any certainty the exact proportion of the substances contained in such compositions.”

[In the examination of an Etruscan mirror, which was placed in my hands for analysis by Professor Gerhardt of Berlin, it was found to consist, in 100 parts, of 67·12 copper, 24·93 tin, and 8·13 lead, approximating closely to an alloy of eight parts of copper to three of tin and one of lead. The oxide of tin obtained in the course of analysis was carefully examined, before the blowpipe, for antimony, but I did not succeed in detecting a trace of that metal. A similar mirror had been likewise analysed by Klaproth; he found 62 per cent. copper, 32 tin, and 6 per cent. lead, but no trace of antimony.--W. F.]

[157] Of such large mirrors Seneca speaks in his Quæst. Nat. lib. i. Of the like kind was the mirror of Demosthenes mentioned by Plutarch, Lucian, and Quintilian.--Institut. Orat. xi. 3, 68, p. 572.

[158] Lib. xxxvi. c. 26, p. 758.

[159] Sueton. in Vita Domit. cap. xiv. p. 334.

[160] Lib. xxxvi. 22, p. 752.--“Cappadociæ lapis, duritia marmoris, candidus atque translucidus, ex quo quondam templum constructum est a quodam rege, foribus aureis, quibus clausis claritas diurna erat.”--Isidor. Origin. 16, 4. Our spar is transparent, though clouds and veins occur in it, like the violet and isabella-coloured, for example, of that found at Andreasberg. Compare this explanation with what Salmasius says in Exercitat. Plin. p. 184.

[161] Lib. xxxvii. cap. 5, p. 774.

[162] Lib. xi. cap. 37, p. 617.

[163] This dissertation of Abat may be found translated in Neuen Hamburg. Magazin. i. p. 568.

[164] Academia di Cortona, vii. p. 34.

[165] Origin. xvi. 7.

[166] Goguet, ii. p. 111. Fabricii Biblioth. Græca. vol. i. p. 70.

[167] Keyssler, i. pp. 17 and 441.

[168] Lib. xxxvii. cap. 7.

[169] De Lapid. § 61.

[170] [This stone acquired its name from its being much used in ornaments by the Incas or Princes of Peru.]

[171] De la Vega, ii. 28.

[172] Montamy in Abhandlung von den Farben zum Porzellan, Leipzig, 1767, 8vo, p. 222, asserts that he saw, in a collection of antiquities, glass mirrors which were covered behind only with a black foil.

[173] Lib. xxxvi. cap. 26, p. 758.

[174] Lib. xxxiii. cap. 9, p. 627.

[175] Trebell. Pollio, Vita Gallien. cap. 12.

[176] Chemical Essays, vol. iv. p. 246.

[177] Plin. lib. xxxiii.: Æs inaurari argento vivo, aut certe hydrargyro, legitimum erat. The first name here seems to signify native quicksilver, and the second that separated from the ore by an artificial process.

[178] Hist. Nat. Supplem. i. p. 451.

[179] Stob. Eclog. Antv. 1575, fol. p. 56.

[180] De Placitis Philos. ii. cap. 20.

[181] In Aratum, cap. 19.

[182] Lib. i. cap. 8.

[183] It is undoubtedly certain, that ὕαλος, which is translated _vitreous_ or _glassy_, means any smooth polished body capable of reflecting rays of light. Originally it signified a watery body; and because watery bodies have a lustre, it was at length used for glass. See Salmas. ad Solin. p. 771.

[184] More observations respecting the opinion of Philolaus may be found in the edition of Plutarch’s work De Placitis Philosophorum by Ed. Corsinus, Flor. 1750, 4to, p. 61, and p. 23.

[185] Professor Heeren having given me his opinion on this passage of Stobæus, I shall here insert it for the satisfaction of the learned reader. The critics, says he, will hardly be persuaded that the words καὶ τὸ ἀπ’ αὐτοῦ πυροειδὲς κατὰ τὸ ἐσοπτροειδὲς are correct, as they can be translated different ways. With regard to the explanation of the matter, I build only on the plain meaning of the words. The author tells us, that Philolaus thought the sun to be a mirror; but we must conclude that he speaks of a mirror such as were then in use; a smooth plate of metal, and not a globe. In this case the first explanation of a glass globe falls to the ground. This is confirmed by Eusebius, who calls it ὑαλοειδὴς δίσκος, though it is possible that the latter word may be a gloss added by some grammarian, or by Eusebius himself. If we enter further into the explanation, we must adopt the plain idea, that the rays of the sun fall upon this plate, and are reflected to us. I am however of opinion, that ὕαλος ought to be translated _glass_, ὑαλοειδὴς _glassy_ or _vitreous_; for the intention of Philolaus evidently was to define the substance of the sun’s body. The result of the whole is, Philolaus considered the sun as a plain plate of glass which reflected the rays or brightness of the æthereal fire. But that he was acquainted with a proper glass mirror does not thence follow with certainty.

[186] Pourquoy reluient les fenestres de verre si fort? Pourtant que la nature de l’estain, duquel elles sont basties par dedans, fort clere, meslée avec le verre cler aussi de lui mesme reluyst d’avantage; et le quel estain outrepassant ses raïons par les petits pores du verre, et augmentant doublement la face extérieure du dit verre, la rend grandement clere.--Problemes d’Alexandre Aphrod., traduit par M. Herret. Paris 1555, 8vo, p. 50.

[187] Origin. lib. xvi. 15, p. 394.

[188] Origin. lib. xvi. 18, p. 396.

[189] Lib. xxxvi. cap. 26, p. 759.

[190] Bayle, Diction. Histor. vol. iv. p. 462.

[191] Printed at Leipzig, 1504, in small folio. There is an edition also printed at Cologne in 1624, and Fabricius quotes a Venetian edition. Pisanus seems to have been a by-name given by some one to Peckham.

[192] Specul. Natur. ii. 78, p. 129.

[193] Ars Magna, cap. lxvii. p. 517, in Lullii Opera. Argent. 1607, 8vo.

[194] Opus Majus, ed. Jebb. Lond. 1733, fol. p. 346.

[195] Franc. Assisiatis et Ant. Paduani Opera. Lugd. 1653, fol.

[196] Nicephori Schol. in Synesium, in Synesii Op. Par. 1612, fol. p. 419.

[197] In the collection of antiquities at St. Denis, an ancient mirror was shown, which was said to have belonged to Virgil. It was oval, and before Mabillon let it fall, was fourteen inches in length and twelve in breadth, and weighed thirty pounds. It is transparent, and of a brownish-yellow colour. According to experiments made on purpose, it was found to consist of artificial glass, mixed with a considerable portion of lead; and as it had been preserved in the above collection from the earliest periods, the practice of adding lead to glass must be very old. But whether this mirror was covered at the back, and how it was covered, though these are the most important points, I find nowhere mentioned. In the collection of the Grand Duke of Tuscany there is a piece of the same kind, said also to have been the mirror of Virgil. See Le Veil, Kunst auf Glas zu malen, Nurnb. 1779, 4to, p. 23, and Hist. de l’Acad. des Sciences, 1737, p. 412.

[198] Villaret, Hist. de France. Par. 1763, xi. p. 142.

[199] In Miscellanea Berolinensia, i. p. 263; but nothing further is said respecting the art, than that it was daily used in the glass-houses. Had I an opportunity, I should make experiments of every kind in order to discover a method of forming plane mirrors also in the like manner.

[200] Wecker, in his book De Secretis, lib. x. p. 572, seems to say, that one must lay the saturated tin leaf so carefully on the glass plate, that no air can settle between them. According to Garzoni, the tin leaf is spread out on a smooth stone table, and after it has been rubbed over with quicksilver, the glass is placed above it.

[201] Tome iii. p. 87, art. _Glace_.

[202] Dict. Géog. de la France. Amst. 1762, fol. v. pp. 415, 672.

[203] A furnace for casting large glass plates, before it is fit to be set at work, cost, it is said, 3500_l._ It seldom lasts above three years, and even in that time it must be repaired every six months. It takes six months to rebuild it, and three months to repair it. The melting-pots are as big as large hogsheads, and contain above 200 cwt. of metal. If one of them burst in the furnace, the loss of the matter and time amounts to 250_l._--TRANS.

GLASS-CUTTING. ETCHING ON GLASS.

I do not here mean to enter into the history of engraving on stone, as that subject has been already sufficiently illustrated by several men of learning well acquainted with antiquities. I shall only observe, that the ancient Greek artists formed upon glass both raised and engraved figures; as may be seen by articles still preserved in collections, though it is probable that many pieces of glass may have been moulded like paste; for that art also is of very great antiquity[204]. It appears likewise that they cut upon plates of glass and hollow glass vessels all kinds of figures and ornaments, in the same manner as names, coats of arms, flowers, landscapes, &c. are cut upon drinking-glasses at present[205]. If we can believe that learned engraver in stone, the celebrated Natter, the ancients employed the same kind of instruments for this purpose as those used by the moderns[206]. They undoubtedly had in like manner a wheel which moved round in a horizontal direction above the work-table, or that machine which by writers is called a lapidary’s wheel.

If this conjecture be true, what Pliny says respecting the various ways of preparing glass is perfectly intelligible. It is turned, says he, by the wheel, and engraven like silver. In my opinion we are to understand by the first part of this sentence, that the glass was cut by the wheel, like stone, both hollow and in relief, though it is possible that drinking-cups or vessels may have been formed from the glass metal by means of the wheel also[207]. In the latter part of the sentence we must not imagine that Pliny alludes to gravers like those used by silversmiths, for the comparison will not apply to instruments or to the manner of working, which in silver and glass must be totally different; but to the figures delineated on the former, which were only cut out on the surface in a shallow manner; and such figures were formed on glass by the ancient artists, as they are by our glass-cutters, by means of a wheel.

Many, however, affirm that the art of glass-cutting, together with the necessary instruments, was first invented in the beginning of the seventeenth century. The inventor is said to have been Casper Lehmann, who originally was a cutter of steel and iron; and who made an attempt, which succeeded, of cutting crystal, and afterwards glass, in the like manner. He was in the service of the emperor Rodolphus II., who, in the year 1609, besides presents, conferred on him the title of lapidary and glass-cutter to the court, and gave him a patent by which every one except himself was forbidden to exercise this new art. He worked at Prague, where he had an assistant named Zacharias Belzer; but George Schwanhard the elder, one of his scholars, carried on the same business to a far greater extent. The latter, who was a son of Hans Schwanhard, a joiner at Rothenburg, was born in 1601; and in 1618 went to Prague to learn the art of glass-cutting from Lehmann. By his good behaviour he so much gained the esteem of his master, who died a bachelor in 1622, that he was left his heir; and obtained from the emperor Rodolphus a continuation of Lehmann’s patent. Schwanhard, however, removed to Nuremberg, where he worked for many of the principal nobility; and by these means procured to that city the honour of being accounted the birth-place of this new art. In the year 1652 he worked at Prague and Ratisbon by command of the emperor Ferdinand III., and died in 1667, leaving behind him two sons, who both followed the occupation of the father. The elder, who had the same christian name as the father, died so early as 1676; but the other, Henry, survived him several years. After that period Nuremberg produced in this art more expert masters, who, by improving the tools and devising cheaper methods of employing them, brought it to a much higher degree of perfection[208].

That the art is of so modern date seems to be confirmed by Zahn, who speaks of it as of a new employment carried on at that time, particularly at Nuremberg. He describes the work-table as well as the other instruments; and gives a figure of the whole, which he appears to have considered as the first[209]. It may be seen, however, from what I have already quoted, that this invention does not belong entirely to the moderns; and, to deny that the ancients were altogether unacquainted with it, would be doing them an injustice. It was forgotten and again revived; and this is the opinion of Caylus.

I must here remark, that before this invention there were artists, who, with a diamond, cut or engraved figures on glass, which were everywhere admired. Without entering, however, into the history of diamonds, which would require more materials than I have yet been able to collect, I will venture to assert that the ancient artists employed diamond dust for polishing or cutting other kinds of stones. Pliny[210] speaks of this in so clear a manner that it cannot be doubted. The same thing has been repeated by Solinus[211], Isidore[212], and Albertus Magnus[213], in a manner equally clear, and Mariette[214] considers it as fully proved; but it does not appear that the ancients made any attempts to cut this precious stone with its own dust; I mean to give it different faces and to render it brilliant. Whether they engraved on it in that manner I cannot pretend to decide, as the greatest artists are not agreed on the subject. Mariette[215] denies that they did; whereas Natter[216] seems not to deny it altogether, and Klotz[217] confidently asserts it as a thing certain. But the last-mentioned author knew nothing more of this circumstance than what he had read in the above-quoted writers.

The question which properly belongs to my subject is, whether the Greeks and the Romans used diamond pencils for engraving on other stones. That many ancient artists assisted their labour by them, or gave their work the finishing touches, seems, according to Natter, to be shown by various antique gems. But even allowing this to have been the case (for at any rate I dare not contradict so eminent a connoisseur), I must confess that I have found no proofs that the ancients cut glass with a diamond. We are however acquainted with the means employed by the old glaziers to cut glass: they used for that purpose emery, sharp-pointed instruments of the hardest steel, and a red-hot iron, by which they directed the rents according to their pleasure.

The first mention of a diamond being used for writing on glass occurs in the sixteenth century. Francis I. of France, who was fond of the arts, sciences, and new inventions, wrote the following lines with his diamond ring upon a pane of glass, at the castle of Chambord, in order to let Anne de Pisseleu, duchess of Estampes, know that he was jealous:

Souvent femme varie,
Mal habil qui s’y fie.

The historian recorded this not so much on account of the admonition, which is not new, as because it was then thought very ingenious to write upon glass[218]. About the year 1562, festoons and other ornaments, cut with a diamond, were extremely common on Venetian glasses, which at that period were accounted the best. George Schwanhard the elder was a great master in this art[219]; and in more modern times, John Rost, an artist of Augsburg, ornamented in a very curious manner with a diamond pencil, some drinking-glasses which were purchased by the emperor Charles VI.

I now come to the art of etching on glass, which properly was the subject of this article. As the acid which dissolves siliceous earth, and also glass, was first discovered in the year 1771, by Scheele the chemist[220], in fluor-spar, one might imagine that the art of engraving with it upon glass could not be older. It has indeed been announced by many as a new invention[221]; but it can be proved that it was discovered as early as the year 1670, by the before-mentioned artist Henry Schwanhard. We are told that some aquafortis having fallen by accident upon his spectacles, the glass was corroded by it; and that he thence learned to make a liquid by which he could etch writing and figures upon plates of glass[222]. How Schwanhard prepared this liquid I find nowhere mentioned; but at present we are acquainted with no other acid but that of fluor-spar which will corrode every kind of glass; and it is very probable that his preparation was the same as that known to some artists as a secret in 1721. The inventor however employed it to a purpose different from that for which it is used at present.

At present the glass is covered with a varnish, and those figures which one intends to etch are traced out through it; but Schwanhard, when the figures were formed, covered them with varnish, and then by his liquid corroded the glass around them; so that the figures, which remained smooth and clear, appeared when the varnish was removed, raised from a dim or dark ground. He perhaps adopted this method in order to render his invention different from the art known long before of cutting the figures on the glass as if engraven. Had he been able to investigate properly what accident presented to him, he might have enriched the arts with a discovery which gave great reputation to a chemist a hundred years after.

I mentioned this old method of etching in relief to our ingenious Klindworth, who possesses great dexterity in such arts, and requested him to try it. He drew a tree with oil varnish and colours on a plate of glass, applied the acid to the plate in the usual manner, and then removed the varnish. By these means a bright, smooth figure was produced upon a dim ground, which had a much better effect than those figures that are cut into the glass. I recommend this process, because I am of opinion that it may be brought to much greater perfection; and M. Renard, that celebrated artist of Strasburg, whose thermometers with glass scales, in which the degrees and numbers are etched, have met with universal approbation, was of the same opinion, when I mentioned the method to him while he resided here, banished from his home by the disturbances in his native country.

It is probable that Schwanhard and his scholars kept the preparation of this liquid a secret, as the receipt for that purpose was not made known till the year 1725, though it is possible that one older may be found in some of those books which treat on the arts. In the above-mentioned year, Dr. John George Weygand, from Goldingen in Courland, sent to the editor of a periodical work a receipt which had been written out for him by Dr. Matth. Pauli of Dresden, then deceased, who had etched, in this manner on glass, arms, landscapes, and figures of various kinds[223]. We find by it that a strong acid of nitre was used, which certainly disengages the acid of fluor-spar, though the vitriolic acid is commonly employed for that purpose[224]. That the Bohemian emerald or _hesphorus_, mentioned in the receipt, is green fluor-spar, cannot be doubted, and will appear still more certain from the history of this species of stone, as far as I am acquainted with it, which I shall here insert.

In the works of the old mineralogists, fluor-spar is either not mentioned, or is classed among their natural glasses and precious stones; and in those of the first systematic writers it is so mingled with quartz and calcareous and gypseous spars, that it is impossible to discover it. The old German miners, however, distinguished it so early as the sixteenth century, and called it _fluss_; because they used it to accelerate the fusion of ores that were difficult to be reduced to that state. Agricola, who first remarked this, changed the German name into _fluor_, an appellation, which, like many others, formed by him from German words, such for example as _quarzum_ from _quarz_, _spatum_ from _spat_, _wismuthum_, _zincum_, _cobaltum_, &c., became afterwards common. If a passage of the ancients can be quoted that seems to allude to fluor-spar, it is that of Theophrastus, where he says that there are certain stones which, when added to silver, copper, and iron ores, become fluid[225]. The first systematic writer who mentioned this kind of stone as a particular genus, was Cronstedt.

Besides being known by its metallurgic use, fluor-spar is known also by having the colours of some precious stones, so that it may be sold, or at least shown as such to those who are not expert judges; because the first time when heated in the dark it shines with a bluish-green lustre. It is possible that fluor-spar may have been among the number of that great variety of stones which the ancients, with much astonishment, tell us shone in the dark; though it is certain that the principal part of them were only light-magnets, as they are called, or such as retain for a certain period the light they have absorbed in the day-time. The observation, however, that fluor-spar emits light after it is heated, seems to have been first made when artificial phosphorus excited the inquiry of naturalists and chemists; and when they began to search in their own country for stones which, in the property of emitting light, might have a resemblance to the Bologna spar, made known about the year 1630. It is well known that the latter is prepared for that purpose by calcination. Stones of the like kind were sought for; and among these fluor-spar, which is not scarce in Germany.

In my opinion, the observation was made in the year 1676; for in that year Elsholz informed the members of the Society for investigating Nature, that he was acquainted with a phosphorus which had its light neither from the sun nor from fire, but which, when heated on a metal plate over glowing coals, shone with a bluish-white lustre; so that by strewing the powder of it over paper, one might form luminous writing. I doubt much whether this experiment was ever tried; at least I find no further account of it in the papers of the Society, nor in the re-publication of the above author’s first dissertation, which appeared in 1681[226].

As far as I know, Kirchmaier, professor at Wittenberg, was the first who disclosed the secret, in the year 1679[227]. Both call this phosphorus the smaragdine; because the ancients speak much of luminous emeralds, and because green fluor-spar is often exhibited as an emerald. Kirchmaier calls this mineral also _hesperus_ and _vesperugo_; and these names have been often given since to fluor-spar, as in the receipt before-mentioned for making a liquid to etch on glass. Kirchmaier’s information, however, must have been very little known; for the Jesuit Casatus, who, in 1684, wrote his Treatise on Fire, was not acquainted with it, as he has inserted only the words of Elsholz. This observation must have been new to Leibnitz himself, and to the Academy of Sciences at Berlin, in 1710; for the former then mentioned it to the Society as a philosophical novelty[228].

I shall remark, in the last place, that the manufacturing of vessels and ornaments of every kind from solid fluor-spar was begun in Derbyshire in the year 1765[229]. The articles formed of it are in England called spar ornaments, and sometimes _blue John_. Many beautiful colours must, as is said, be brought forward by means of fire. But the heat must be applied with great caution; for fluor-spar, as is well known, by a strong and particularly a sudden heating, cracks, and loses its transparency. Since writing the above, I find that M. Raspe[230] denies this bringing forward of colours by fire.

FOOTNOTES

[204] Mariette, Traité des Pierres gravées. Par. 1750, fol.

[205] The two ancient glasses found at Nismes, and described in Caylus’ Recueil d’Antiquités, ii. p. 363, were probably of this sort.

[206] Natter, Traité de la Méthode antique de graver en Pierres fines, comparé avec la Méthode moderne. Lond. 1754, fol.

[207] Of this kind were the _calices audaces_ of Martial, xiv. 94, and those cups which often broke when the artist wished to give them the finishing touch.

[208] See Sandrart’s Teutsche Akademie, vol. i. part 2, p. 345, where there is much valuable information respecting the German artists. Compare also Doppelmayer’s Nachricht von Nürnberg. Künstlern.

[209] Oculus Artificial. iii. p. 79.

[210] Lib. xxxvii.

[211] Cap. 52, p. 59.

[212] Origin. xvi. 8.

[213] De Miner. lib. ii. 2.

[214] Traité des Pierres gravées, i. pp. 90, 156.

[215] Ibid. p. 156.

[216] In the preface, p. 15.

[217] Ueber den Nutzen d. geschnitt. Steine. Altenb. 1768, p. 42.

[218] Le Veil, iii. p. 19. This anecdote however is not mentioned by Mezeray, Castelnau, or Laboureur; and Bayle must have been unacquainted with it, or he would have introduced it into his long article on the Duchesse d’Estampes.

[219] Doppelmayer, p. 232.

[220] Abhandlungen der Schwed. Akad. xxxiii. p. 122.

[221] Halle, Fortgesetzte Magie. Berlin, 1788, 8vo, i. p. 516. This author says that the invention came from England, where it was kept very secret; but the honour of the second invention belongs to H. Klaproth.

[222] Schwanhard, by the acuteness of his genius, proved what was before considered as impossible, and found out a corrosive so powerful that the hardest crystal glass, which had hitherto withstood the force of the strongest spirits, was obliged to yield to it, as well as metals and stones. By these means he delineated and etched on glass, figures of men, some naked and some dressed, and all kinds of animals, flowers, and plants, in a manner perfectly natural; and brought them into the highest estimation.--Sandrart, Teutsche Akademie, i. 2, p. 346.--Doppelmayer, p. 250, says, “After 1670 he accidentally found out by the glass of his spectacles, upon which some aquafortis had fallen, becoming quite soft, the art of etching on glass.”

[223] Breslauer Sammlung zur Natur- und Medicin-Geschichte. 1725, January, p. 107. “Invention of a powerful acid by which figures of every kind, according to fancy, can be etched upon glass.--When _spiritus nitri per distillationem_ has passed into the recipient, ply it with a strong fire, and when well dephlegmated, pour it, as it corrodes ordinary glass, into a Waldenburg flask; then throw into it a pulverised green Bohemian emerald, otherwise called _hesphorus_ (which, when reduced to powder and heated, emits in the dark a green light), and place it in warm sand for twenty-four hours. Take a piece of glass well cleaned and freed from all grease by means of a lye; put a border of wax round it, about an inch in height, and cover it all equally over with the above acid. The longer you let it stand the better, and at the end of some time the glass will be corroded, and the figures, which have been traced out with sulphur and varnish, will appear as if raised above the plane of the glass.” This receipt has been inserted by H. Krunitz in his Œkonomische Encyclopedie, xi. p. 678.

[224] Klindworth covers the glass with the etching ground of the engravers; but in the Annals of Chemistry for 1790, ii. p. 141, a solution of isinglass in water, or a turpentine oil varnish, mixed with a little white lead, is recommended. Complete instructions for acquiring this art may be found there also.

[225] De Lapidibus, sect. 19.

[226] See Ephemerid. ac Nat. Cur. 1676, Dec. 1, obs. 13, p. 32; and Elsholtii De Phosphoris Observationes, Berol. 1681, 4to.

[227] G. C. Kirchmaieri De Phosphoris et Natura Lucis, necnon de Igne, Commentatio Epistolica. Wittebergæ, 1680, 4to.

[228] Miscellanea Berolin. 1710, vol. i. p. 97. The fluor-spar earth, or phosphoric earth, as it is called, which in later times has been found in marble quarries, and which some at present consider as an earth saturated with phosphoric acid, is mentioned by the Swede Hierne, in Prodromus Hist. Nat. Sueciæ. Henkel had never seen it.

[229] Watson’s Chemical Essays, ii. p. 277.

[230] Descriptive Catalogue of Tassie’s Engraved Gems, Lond. 1791, 2 vols. 4to, i. p. 51.

SOAP.

That the first express mention of soap occurs in Pliny and Galen, and that the former declares it to be an invention of the Gauls, though he prefers the German to the Gallic soap[231], has already been remarked by many. Pliny says that soap[232] was made of tallow and ashes; that the best was made of goats’ tallow and the ashes of the beech-tree, and that there were two kinds of it, hard and soft. The author of a work on simple medicines, which is ascribed to Galen, but which however does not seem to have been written by that author, and of which only a Latin translation has been printed, speaks of soap being made by a mixture of oxen, goats’, or sheep’s tallow, and a lye of ashes strengthened with quicklime. He says the German soap was the purest, the fattest, and the best, and that the next in quality was the Gallic[233]. This account corresponds more exactly with the process used in Germany at present; whereas the French use mineral alkali, and instead of tallow, employ oil, which appears to be a later invention. Pliny in his description does not speak of quicklime; but as he mentions a mixture of goats’ tallow and quicklime a little before, it is probable that the use of the latter was then known at Rome. Gallic and German soap are often mentioned by later writers[234], as well as by the Arabians, sometimes on account of their external use as a medicine, and sometimes on account of their use in washing clothes. The latter purpose is that for which soap is principally employed in modern times; but it does not seem to have been the cause of German soap being introduced at Rome. Washing there was the occupation of indigent scourers, who did not give themselves much trouble concerning foreign commodities. The German soap, with which, as Pliny tells us, the Germans coloured their hair red, was imported to Rome for the use of the fashionable Roman ladies and their gallants. There is no doubt that the _pilæ Mattiacæ_, which Martial recommends as a preventive of gray hair[235]; the _caustica spuma_ with which the Germans dyed their hair[236]; and the Batavian froth or lather which the Romans employed for colouring theirs[237], were German soap. It is probable that the Germans tinged it with those plants which were sent to Rome for dyeing the hair[238]; and according to the modern manner of speaking, it was more properly a kind of pomade than soap.

It appears that the Romans at first considered hair-soap as an ointment made from ashes; for we read in various passages of ancient authors, that the hair was dyed by means of ashes, or an ointment made of ashes and a certain kind of oil. It is however possible that they may have had such an ointment, which undoubtedly would be of a saponaceous nature, before they were acquainted with the German soap, or that they imitated the German pomade with different variations[239].

As soap is everywhere used for washing at present, a question arises what substitutes were employed before it was invented. Those with which I am acquainted I shall mention and endeavour to illustrate. They are all still used, though not in general; and they are all of a soapy nature, or at least have the same effects as soap; so that we may say the ancients used soap without knowing it.

Our soap is produced by a mixture of lixivious salts and tallow, by which means the latter becomes soluble in water. The greater part of the dirt on our linen and clothes consists of oily perspiration or grease, or dust which that grease attracts, and which either cannot be washed out, or, but very imperfectly, by water alone. But if warm water, to which lixivious salts have in any manner been added, be taken, and if dirty cloth be rubbed in it, the greasy dirt unites with the salts, becomes saponaceous, and is so far soluble in water that it may be washed out. There are also natural juices which are of a soapy quality, in the state in which we find them, and which can be employed in the stead of artificial soap. Of this kind is the gall of animals and the sap of many plants. The former being less strong in its effects on account of its slimy nature, is used at present particularly for coloured stuffs, the dye of which is apt to fade. As far as I know, however, it was not employed by the ancients[240], but it is certain that in washing they used saponaceous plants.

In the remotest periods it appears that clothes were cleaned by being rubbed or stamped upon in water, without the addition of any substance whatever. We are told by Homer, that Nausicaa and her attendants washed their clothes by treading upon them with their feet in pits, into which they had collected water[241]. The epithet black, which the poet gives to the water, might induce one to conjecture that it had been mixed with ashes, which would convert it into a lye; but where were the ashes to be found? Had they brought them along with them, the bard, where he before enumerates everything that they carried with them, and even oil, would not have failed to mention them; and such a conjecture is rendered entirely groundless by his applying the same epithet to pure water, in other places, where nothing can be supposed to have coloured it[242]. Water, when it stands in deep pits, reflects so few rays of light, that in a poetical sense it may very properly be called black.

We find however mention made at later periods of ashes, and a lye of ashes employed for washing; but I think very seldom, and I do not know how old the use of them may be. According to Julius Pollux, _konia_, mentioned by Aristophanes and Plato, was a substance used for washing; and he says expressly, that we are to understand by it a lye of ashes. This I mention for the sake of those, who, like me, place little confidence in the terms of art given in dictionaries. With the above lye, oil- and wine-jars were cleaned[243]; and it was employed also for washing the images of the gods[244]. The method of strengthening the lye by means of unslaked lime was known, at any rate, in the time of Paulus Ægineta; but it appears that the Romans were not acquainted with the salt itself, which is procured by dissolving common wood-ashes in water: I mean, they did not understand the art of producing it in a dry solid form, or of boiling potashes.

On the other hand, that fixed lixivious salt, the mineral which nature presents in many of the southern countries, was long known and used in washing. This was the _nitrum_, or, as the people of Attica pronounced it, the _litrum_, of the ancients, as has already been remarked by others[245]. It would however be worth the trouble to investigate the proofs still further. By examining them with more mineralogical and chemical knowledge than have hitherto been employed for that purpose, they might be further strengthened, and serve to illustrate many obscure passages. For my part, I have neither leisure nor room here to undertake such a task, though I have collected many observations relative to that subject. It is certain at any rate, that the ancients employed _nitrum_ for washing, and it is evident from the testimony of various authors, that it was much used in the baths[246].

That the people of Egypt, in the time of Pliny, made mineral alkali also from the ashes of some plants, we have reason to conclude, because he says that it was necessary to put the Egyptian nitre into vessels well-corked, else it became liquid. Natural alkali is never liable to do so, unless it be very much burnt; and as no reason is assigned for its assuming that form, we may believe that the Egyptian alkali was the strongly burnt ashes of those plants which are still used in Egypt for making salt, and perhaps the same with which the Spaniards were made acquainted by the Arabians, and which they cultivate for making soda.

Strabo speaks of an alkaline water in Armenia, which was used by the scourers for washing clothes[247]. Of this kind also must have been the lake Ascanius, which is mentioned by Aristotle[248], Antigonus Carystius[249], and Pliny[250]. It is worthy of remark, that the ancients made ointments of this mineral alkali and oil, but not hard soap, though by these means they approached nearer to the invention than the old Germans in their use of wood-ashes; for dry solid soap can be made with more ease from the mineral than the vegetable alkali; and when Hungarian, French, and German soap are of equal goodness, the last does more credit to the manufacturers because they cannot employ the mineral alkali. I shall here observe, that this alkali was used for washing by the Hebrews, and that it occurs in the sacred writings under the name of _borith_[251].

The cheapest however, and the most common article used for washing, was the urine of men and animals. When this excrement becomes old, the alkali disengages itself, which may be perceived by its fœtid smell; and such alkalised urine being warmed, and employed to wash greasy clothes, produces the same effects as the _nitrum_ of the ancients. It is still used for the like purpose in our cloth manufactories.

To procure a supply of it, the ancient washers and scourers placed at the corners of the streets, vessels which they carried away after they had been filled by the passengers, who were at liberty to use them; and the practice of having such conveniences was certainly more decent than that of employing the walls of churches and other buildings, which the police of Dresden forbade some years ago, but with no effect. At Rome, that which at present spoils and renders filthy our noblest edifices, was converted to use. When clothes were washed, they were trod upon with the feet, as was the case in the cloth manufactories at Leeds, Halifax, and other places of England, where the urine was collected by servants, and sold by measure to the manufacturers under the name of _old lant_. On account of the disagreeable smell attending their employment, scourers at Rome were obliged to reside either in the suburbs or in some of the unfrequented streets[252].

My readers here will undoubtedly call to remembrance the source of taxation devised by the emperor Vespasian, who, as his historians tell us, _urinæ vectigal commentus est_[253]. It is not certainly known in what manner this impost was regulated. Did the emperor declare that article, which was not _subterraneum rarius_, to be a regale as a _res derelicta_, so that the scourers were obliged to pay him what he thought a reasonable sum proportioned to the benefit which they derived from it? Or was it imposed only as a poll-tax? For every tax upon anything indispensably necessary to all, is, to speak in the language of finance, the same as what is called a poll-tax, or a tax paid by every one who has a head. The latter conjecture is the most probable, especially as this tax continued two centuries, till the time of Anastasius, and as we read also of _vectigal pro urina jumentorum et canum_, which was exacted from every person who kept cattle. Vespasian therefore was not fortunate in the choice of a name for his tribute, which on that account must have been undoubtedly more detested. A poll-tax at present is called by those who do not speak favourably of it, the Turkish-tax, because the Turks impose it on all unbelievers. When it was introduced by Louis XIV. in 1695, he called it _la capitation_.

Of plants with a saponaceous juice, the ancients, at any rate, used one instead of soap; but it is difficult or rather impossible to define it. I shall not therefore content myself merely with transcribing the passages where it is mentioned, but I shall arrange whatever I can find respecting it in such a manner, as, according to my opinion, the names of plants ought to be explained in dictionaries.

Στρουθίον, Struthium, Latinis Herba lanaria, et Plinio etiam Radicula.

1. Est planta spinosa, _Theophrastus_, _Plinius_.

2. Grata aspectu, sed sine odore, _Theophrastus_, _Plinius_.

3. Folio oleæ, _Plinius_; vel papaveris Heraclei, _Theophrastus_.

4. Caule ferulaceo, tenui, lanuginoso, eduli, _Plinius_.

5. Radice magna, acri, medicinali, _Plinius_, _Dioscorides_;
spumescente, _Lucian_.

6. Floret æstate, _Theophrastus_. _Plinius_; sed semen nullum,
_Plinius_.

7. Nascitur saxosis et asperis locis, _Plinius_.

8. Sponte, præcipue in Asia Syriaque; trans Euphratem laudatissima;
sativa ubique, _Plinius_.

9. Radix conditur ad lanas lavandas, _Theophrastus_, _Plinius_,
_Dioscorides_, _Columella_, et alii.

10. Herba ovibus lac auget, _Plinius_.

The above is all that the ancients have told us respecting this plant. The information is indeed very scanty, and at the same time it is not altogether certain; but even if it were, it would be sufficient only to confute some conjectures, but not to establish the systematic name of the plant. I call the properties of it described to us uncertain: first, because I do not know whether Pliny did not mean to distinguish the wild plant from that which was cultivated, and many have understood as alluding to the former that which I have applied to both: secondly, because the words of Theophrastus, being in one passage evidently corrupted, will admit of various constructions; and because in another, on account of some exceptions, of which he speaks, they appear at least to me unintelligible: thirdly, because Pliny, who gives us the best account of it, is the only author who calls the _struthium_ or soap-plant _radicula_, a name by which is rather to be understood a dye-plant of the same kind as madder. We have reason therefore to suspect that he has confounded the properties of the two plants, especially as the fourth property was ascribed by others to a _Rubia_, _Asperula_, or _Galium_, which was cultivated in Syria, and named often _radicula Syriaca_. On the other hand, this diminutive is very ill-suited to a root which Pliny himself calls large.

The words of that author, “tingenti, quicquid sit cum quo decoquatur,” have been by some explained as if he meant that the _struthium_ was a dye-plant, though as a soapy plant it must have been destitute of colour; and they have hence deduced a proof that Pliny confounded the _struthium_ with the _radicula_ used in dyeing. On the other hand, Hardouin reads _unguentis_ instead of _tingenti_. He assures us that he found the former in manuscripts, and is of opinion that the sap of the _struthium_ was used also for ointments.

In my opinion, however, _tingenti_ must be retained; and the meaning is that when cloth was to be dyed it was necessary to prepare it for that purpose by soaking it and washing it with the sap of this plant. This he expressly tells us himself; “tingentibus et radicula lanas præparat.” It is probable that the ancient dyers mixed their dye-liquors with the juice of the _struthium_, for the same purpose as bran and the seeds of fenugreek are added to dye-liquors at present; that is, to render them thicker and more slimy, in order that the colouring particles may be longer and more equally suspended in or diffused through them[254]. The words _quidquid sit cum quo decoquatur_ will now become intelligible. Whatever may be employed for dyeing, says the author, the addition of the juice of the _struthium_ is serviceable.