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XI. On the Specific Gravity of Alloys. By A. Matthiessen, Ph.D. 
Communicated hy Professor Wheatstone. 
Eeceived November 17, — Eead December 22, 1859. 
Befoee commencing a research on the law of the conducting power for electricity of 
alloys, it was considered necessary to determine their specific gravities; to ascertain 
whether they expand or contract, so as to be able to account for differences which 
might be obtained in then conducting powers. 
The metals used for the alloys were those which were easily obtained in a pure state 
in large quantities, and were purified as follows : — 
1. Antimony. — By Liebig’s process. 
2. Tin. — Commercial metal dissolved in nitric acid, and the binoxide reduced by 
charcoal. 
3. Cadmium. — Commercial metal dissolved in hydrochloric acid and precipitated by 
sulphuretted hydrogen ; the sulphide dissolved in hydrochloric acid and precipitated by 
carbonate of soda ; the carbonate heated, a part of the oxide reduced by hydrogen, and 
the rest distilled with charcoal. 
4. Bismuth. — Commercial metal dissolved in nitric acid, precipitated by water and 
reduced by charcoal. 
5. Silver. — Eeduced from the pure chloride by fusion with carbonate of soda. The 
greater part of the silver used for making the alloys was procured in a state of purity 
from Messrs. Johnson and Matthey. 
6. Lead. — Commercial acetate recrystallized three times and heated. 
7. Mercury. — Commercial metal treated with nitric acid, and allowed to stand with 
it about a month, being at intervals well-shaken. 
8. Gold. — Prepared by precipitating chloride of gold by algaroth powder, &c., and 
also by precipitation of the chloride of gold by protosulphate of u’on*, &c. Some of 
the gold employed was procured pure from Messrs. Johnson and Matthey. 
The quantity of each alloy made was about 20 grms. ; the two metals were weighed 
out accurately in proper proportions, and fused together in a porcelain crucible ; a jet 
of gas being allowed to play in the same from above to prevent the oxidation of the 
metals. The alloys were cast in a wooden mould, a porcelain slab (previously blackened 
by holding it over a gas flame to prevent the adhering of the metal) forming the bottom. 
They were always re-fused and re-cast, at least three times, before the first determination 
was made, then re-fused before they were determined a second time, and again before 
* See Appendix at the end of my paper “ On the Electric Conducting Power of Alloys,” in this 
volume, p. 175. 
MDCCCLX. 2 B 
