28 ON THE ALLOYS OF COPPER AND ZINC. 
peculiarities of structure and of superficial coloration which occur among the different 
alloys. To these points I shall again allude. 
The method which I have used in preparing the alloys has varied slightly according 
to the amount of copper contained in them. Those in which the proportion of copper 
was large were prepared by projecting granulated zinc by small portions into the mol- 
ten copper, the crucible which contained it having been previously removed from the 
fire, the mixture being thoroughly stirred after each addition of zinc. This method 
succeeds very well when only a small amount of zinc is to be combined with the 
copper, perfect combination of the metals being readily obtained while the loss of zinc 
from volatilization, though considerable, is, if proper care be exercised, much less 
than would be at first sight supposed. But for alloys containing even as much as 
50 or 55 per cent of zinc, this method becomes uncertain. 
It is in this case necessary to bring the copper to a high degree of heat before 
adding the zinc; yet in spite of this precaution, and of the utmost care in adding 
the zinc only by small portions, which have previously been made as hot as possible, 
the mass contained in the crucible will often become chilled, and require to be again 
placed in the furnace in order to be remelted. Since the portion of zinc last added 
remains uncombined with the copper, and exposed at the surface of the mass, a great 
deal of it is lost during this operation. 
In preparing alloys containing more than 50 per cent of zinc, I have melted the 
copper and zinc in separate crucibles, and have subsequently poured the zinc upon 
the copper. It is necessary to remove from the fire the crucible which contains 
the latter, and to cover it carefully, with the exception of a small opening through 
which the zinc may be poured; for violent ebullition and projection of particles 
of the melted metal occur during the first moments of combination. After thorough 
stirring * in either case, the mass was allowed to cool until a crust had formed on the 
surface of the alloy. This crust was then pierced, and the fluid matter beneath 
it poured out. The cup thus formed, having been removed from the crucible, was 
sawed in two, and portions of the crystals upon its sides cut off by means of a cold- 
chisel, for analysis. The sheets obtained from the fluid alloy poured off were also 
retained, and were subsequently analyzed. 
The weight of alloy obtained in each experiment varied from two to six pounds. 
By operating in the manner described, it is easy — especially after a little practice 
* I have found that a rod of soapstone eight or ten inches in length, cut somewhat tapering towards 
its point, screwed into a piece of ordinary one-inch iron gas-pipe, forms a very convenient stirrer. It should 
be ignited to expel moisture before Mnt used. : 
