ON THE ALLOYS OF COPPER AND ZINC. 31 
has himself obtained from the receiving-vessels of the Silesian zinc furnaces, and 
which are, for that matter, familiar enough to those who have often had occasion to 
fuse zinc in covered crucibles. I would, however, suggest, that the circumstances 
under which these mammelons are formed are by no means identical with those 
in which Nicklés's crystals were prepared,* viz. in an atmosphere of hydrogen, at a 
lower heat, and doubtless with less rapid volatilization.T 
On the other hand, the very fact which I have myself observed, namely, that most, 
and probably all, alloys of copper and zinc may be crystallized in octahedrons, is in 
itself strong presumptive evidence that zinc is capable of assuming a similar form. 
Indeed, in the absence of any marked tendency in these alloys to separate by eliqua- 
tion, there remains no hypothesis other than that of isomorphous mixture by which 
to explain their composition. 
* Vid. Jacquelain, Ann. Ch. et Phys. (3.) VII. 204; and Favre, loc. cit. 
f I have endeavored to defend Nicklés's observation, the more especially because it is certainly as 
well entitled to be received by chemists as the experiments of Noeggerath (Pogg. Ann. XXXIX. 323) 
and Rose, which go to prove that zinc may crystallize in forms of the hexagonal system. Neither of 
these observers has analyzed the crystals which he has described, all of which were accidental products 
of smelting-works. Now we know from the researches of Cooke (Memoirs of the American Academy, New 
Series, V. 353; also, Am. J. Sci. (2.) X X. 225), that zinc, which contains only three or four per cent, and prob- 
ably even a smaller quantity, of antimony, has a strong tendency to crystallize in the form of rhombic prisms 
of the compound Sb Zn; with excess of zinc. We have also the statements of Laurent and Holms (Ann. Ch. 
et Phys. 1835, (2.) LX. 333), that zinc containing three or four per cent of iron crystallizes in rhombic prisms ; 
and of Warren de la Rue (Phil. Mag. J. (3.) XXVII. 370; also, J. pr. Chem. (N. F.) XXXVII. 126), who 
has obtained and measured rhombic prisms of composition, — 
Zinc > e ; í ; 3 i S 90.00 
Iron S S P 3 S e e ; sae 
Lead i . è e S : b e 6.00 : 
Duis e x wl ll... JE. 
100.00 
% 
A. Erdmann (Berzelius, Traité, IT. 620) also has analyzed acicular crystals of zinc which were detached 
from a bit of distilled zinc which had been used to decompose a quantity of chloride of silver. These 
needles contained, — 
. Zine wil s , . » 4 ale : 93.193 
MON . : e i . e e EE EE PME 
Lead $ A è . : . : : 0.283 
100.000 
In view of all these data, showing the very great influence which the presence of a small amount 
of impurity may exert upon the crystalline form of zinc, the importance of the fact that we have no 
evidence whatsoever of the purity of the crystals described by Noeggerath and Rose is manifest. 
