ON THE IMPURITIES OF COMMERCIAL ZINC. 61 
ence of very small quantities of arsenic, and possibly of antimony, in many of the 
zincs of.commerce is undeniable, but (he amount of these metals present is so infini- 
tesimal, that they can only be detected qualitatively by the most delicate tests, and a 
quantitative determination of either of them we regard as so nearly impossible as to 
be untrustworthy and incredible. A full discussion of the subject of arsenic as an 
impurity in commercial zinc will be found below. The occurrence of nickel, cobalt, 
and manganese in zinc has been denied just as often as it has been asserted, but it 
is of course impossible to assert the universal negative, that these metals are never to 
be found in any spelter, for zinc is an article of commerce which is manufactured in 
many different places, by various processes, from several different ores. Thus much 
. may be safely asserted, that if nickel, cobalt, and manganese are ever to be found in 
commercial zinc, they occur there accidentally, exceptionally, abnormally, and in quan- 
tities hardly to be appreciated, and utterly insignificant. 
But few quantitative determinations of the impurities of zinc are recorded, but we 
can confirm the results we have obtained with Silesian zinc by referring to the previous 
analyses of German zincs by several chemists. Thus Wackenroder,* in the memoir 
already ‘cited, maintains that the principal impurities of Silesian zinc are lead, cad- 
mium, and iron ; and after him, Karsten draws the same conclusion from a considerable 
number of analyses of zincs from different works. In thirty-two analyses of Silesian 
zincs made by this eminent metallurgist, the amount of lead found varies from 0.24 
per cent to 2.36 per cent.t A few other analyses we cite below.f 
* Ann. der Pharm., 1834, X. 53. 
.f Archiv. f. Mineralogie, Karsten u. Dechen, 1842, XVI. 597. Also in Dinglers Polyt. Jour., 1842, 
LXXXVI. 193. |. 
į An East-Indian zinc, which Bonnet analyzed, contained, i in 100 parts, 0. 43 of lead, and 0.24 of iron. Ann. 
der Pharm., 1834, IX. 184. Jansen obtained a black residue weighing 2} ounces from 8 pounds of Silesian 
zinc. He states the result of an analysis of the residue as follows. (Ibid. 191.) The statement does not 
admit of any verification, is unintelligible and incredible. 
WOU . — 5 e e 297 
DEPO. —. | 3) s» € ^ -.* 1.88 
« “Copper, . . 156 
FON |C40 . ooo PA V^ a808 
Carbide of Zinc, . i » 05,08 
Silicium, . d d 3 š i e ^ t . 13.77 
DEUM - i PN OI Jas 2.26 
Residue of Sand and Cast g e d A . . 18.00 
1038.36 
Wittstein found in one sort of Austrian zinc as much as 34 per cent of lead. Cited in Ann. der 
