56o BOOK XII. 



Native as well as manufactured nitrum is mixed in vats with urine 

 and boiled in the same caldrons ; the decoction is poured into vats in which 

 are copper wires, and, adhering to them, it hardens and becomes chrysocolla, 

 which the Moors call borax. Formerly nitrum was compounded with 

 Cyprian verdigris, and ground with Cyprian copper in Cyprian mortars, as 

 Pliny writes. Some chrysocolla is made of rock-alum and sal-ammoniac.^ 



soda and potash in distinction to nitre for saltpetre, and later natron was applied solely to soda. 



It is desirable to mention here two other forms of soda and potash which are frequently 

 mentioned by Agricola. "Ashes which wool dyers use" {cineres quo infectores lanarum utuntur). — 

 There is no indication in any of Agricola's works as to whether this was some special wood- 

 ash or whether it was the calcined residues from wool washing. The " yolk " or " suint " of 

 wool, originating from the perspiration of the animal, has long been a source of crude potash. 

 The water, after washing the wool, is evaporated, and the residue calcined. It contains 

 about 85% K2COS, the remainder being sodium and potassium sulphates. Another reason 

 for assuming that it was not a wood-ash product, is that these products are separately 

 mentioned. In either event, whether obtained from wool residues or from lixiviation of 

 wood-ash, it would be an impure potash. In some methods of wool dyeing, a wash of soda 

 was first given, so that it is barely possible that this substance was sodium carbonate. 



" Salt made from the ashes of musk ivy" {sal ex anthyllidis cinere f actus, — Glossary. 

 salalkali). This would be largely potash. 



*This paragraph displays hopeless ignorance. Borax was known to Agricola and 

 greatly used in his time ; it certainly was not made from these compounds, but was imported 

 from Central Asia. Sal-ammoniac was also known in his time, and was used like borax as 

 a soldering agent. The reaction given by Agricola would yield free ammonia. The follow- 

 ing historical notes on borax and sal-ammoniac may be of service. 



Borax. — The uncertainties of the ancient distinctions in salts involve borax deeply. 

 The word Baurach occurs in Geber and the other early Alchemistic writings, but there is 

 nothing to prove that it was modern borax. There cannot be the slightest doubt, however, 

 that the material referred to by Agricola as borax was our borax, because of the characteristic 

 qualities incidentally mentioned in Book VII. That he believed it was an artificial product 

 from nitrum is evident enough from his usual expression "chrysocolla made from nitrum, 

 which the Moors call borax." Agricola, in De Natura Fossilium (p. 206-7), makes the 

 following statements, which could leave no doubt on the subject : — " Native nitrum is found 

 " in the earth or on the surface. . . . It is from this variety that the Venetians make 

 " chrysocolla, which I call borax. . . . The second variety of artificial nitrum is made 

 " at the present day from the native nitrum, called by the Arabs linear, but I call it usually 

 " by the Greek name chrysocolla ; it is really the Arabic borax. . . . This nitrum does not 

 " decrepitate nor fly out of the fire ; however, the native variety swells up from within." The 

 application of the word chrysocolla [chrysos, gold ; colla, solder) to soldering materials, and 

 at the same time to the copper mineral, is of Greek origin. If any further proof were needed 

 as to the substance meant by Agricola, it lies in the word linear. For a long time the borax 

 of Europe was imported from Central Asia, through Constantinople and Venice, under the 

 name of tincal or linear. When this trade began, we do not know ; evidently before 

 Agricola's time. The statement here of making borax from alum and sal-ammoniac is 

 identical with the assertion of Biringuccio (11., 9). 



Sal-ammoniac. — The early history of this — ammonium chloride — is also under a 

 cloud. Pliny (xxxi., 39) speaks of a sal-hammoniacum, and Dioscorides (v., 85) uses much 

 the same word. Pliny describes it as from near the temple of Ammon in Egypt. None 

 of the distinctive characteristics of sal-ammoniac are mentioned, and there is every 

 reason to believe it was either common salt or soda. Herodotus, Strabo, and others mention 

 common salt sent from about the same locality. The first authentic mention is in Geber, 

 who calls it sal-ammoniacum, and describes a method of making, and several characteristic 

 reactions. It was known in the Middle Ages under various names, among them sal-aremonicum. 

 Agricola (De Nat. Fos., iii., p. 206) notes its characteristic quality of volatilization. " Sal- 

 " ammoniac . . in the fire neither crackles nor flies out, but is totally consumed." He 



also says (p. 208) : " Borax is used by goldsmiths to solder gold, likewise silver. The 

 " artificers who make iron needles (tacks ?) similarly use sal-ammoniac when they cover the 

 " heads with tin." The statement from Pliny mentioned in this paragraph is fromxxxiii., 

 29, where he describes the chrysocolla used as gold solder as made from verdigris, nitrum, 

 and urine in the way quoted. It is quite possible that this solder was sal-ammoniac, 

 though not made in quite this manner. Pliny refers in several places (xxxiii., 26, 27, 28, 

 and 29, xxxv., 28, etc.) to chrysocolla, about which he is greatly confused as between gold- 

 solder, the copper mineral, and a green pigment, the latter being of either mineral origin. 



