ON THE ALLOYS OF COPPER AND ZINC. : 33 
As a rule, however, all of the crystals obtained closely resemble those delineated 
in Fig. 1, Indeed, this figure might be used to represent almost any specimen 
in the long series of alloys which I have prepared. 
Very fine groups of crystals were obtained from those 
alloys which contained only one or two per cent 
of zinc. It is worthy of note, that, although these 
crystals have the same form and general appear- 
ance as those prepared by the same method from 
an equal quantity — three or four pounds — of pure 
copper, they are nevertheless much larger and more 
perfect. Since they may, for all practical purposes, 
be considered as crystals of copper with slight impurity of zinc, and are easily to be 
obtained, it would almost seem advisable to add one or two per cent of zinc to the 
metal employed in preparing specimens of crystallized copper for the cabinet. A simi- 
lar case is presented by lead, which is very readily crystallized when it contains a little 
antimony: a fact well exemplified by the beautiful cups of crystals of Kriútzblei 
which are prepared by partially cooling the metal in ladles, at the Frankensharner 
smelt-works near Clausthal, and doubtless at other localities in the Hartz. 
Since the crystals rich in copper which have just been described do not possess 
in any marked degree the yellow color peculiar to brass, they are somewhat less 
interesting than those obtained from alloys containing more zinc. Crystals of 
the latter can be obtained with the greatest ease by remelting old brass, or, better, 
by filling a Hessian crucible from the molten metal of the pots of a brass-founder, 
in which case all annoyance from the formation of a false crust of mixed ox- 
ide of zinc and metal is obviated. I mention these details, because I have myself 
found it somewhat difficult to acquire the knack of obtaining at will good crystals, 
when the alloys were prepared directly from the pure metals; having frequently 
been compelled to repeat a single experiment three or four times before satisfactory 
results were obtained. This is owing to the different degrees of rapidity with which 
the alloys cool, a fact to which I have already alluded. 
The most perfect individual crystals were obtained from a quantity of brazier's 
solder which had been prepared at the foundery of the Revere Copper Company 
in Boston by fusing together 50 parts of copper with 50 parts of zinc. When 
an alloy of about this composition solidifies, and especially if it be suddenly cooled, — 
as happens when itis poured into iron ingot-moulds, — it assumes, as is well known, 
a highly crystalline structure, consisting almost entirely of a mass of coarse fibres 
VOL. VIII. 5 
