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 chrysocoUa is made of rock-alum and sal-ammoniac.8
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 woodash 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% K2CO3, 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 factus,—Glossary.
salalkali). This would be largely potash.
8This 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 following 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 earlji 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 "chrysocoUa 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
" chrysocoUa, 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 chrysocoUa ; 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 chrysocoUa (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 tincar. For a long time the borax
of Europe was imported from Central Asia, through Constantinople and Venice, under the
name of tincal or tincar. 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 Ammoh 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., m., 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 from xxxiii.,
29, where he describes the chrysocoUa 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. Puny refers in several places (xxxili., 26, 27, 28,
and 29, xxxv., 28, etc.) to chrysocoUa, about which he is greatly confused as between goldsolder, the copper mineral, and a green pigment, the latter being of either mineral origin.
