ALLOY 



By amalgamation and straining through chamois leather, he obtained crystalline 

 metallic compounds of gold, bismuth, lead, and cadmium, -with mercury, which 

 appeared to exist in true definite proportions. With potassium he obtained two 

 amalgams, KHg 20 and KHg 25 . With silver, by bringing mercury in contact with 

 a solution of nitrate of silver, according to the quantity of mercury employed, lie 

 obtained such amalgams as Ag 5 Hg 16 , AgHg 2 , AgHg 8 , AgHg 1 . 



Beyond those there are many experiments which appear to prove that alloys are 

 true chemical compounds ; but, at the same time, it is highly probable that the 

 true chemical alloy is very often dissolved (mechanically disseminated) in that metal 

 which is largely in excess. In some cases, however, the alloy appears to be nothing 

 more than a mechanical mixture of the component metals. 



Some years since, the Editor, at the request of Sir Henry Do la Beche, and guided 

 by the advice of Professor Graham, carried out a series of experiments in the laboratory 

 of the Museum of Practical Geology, with the view of obtaining a good alloy for 

 soldiers' medals, and the results confirmed the views respecting the laws of definite 

 proportional combination among the metals. Many of those alloys were struck at the 

 Mint, and yielded beautiful impressions; but there were many objections urged 

 against the use of any alloy for a medal of honour. 



One metal does not alloy indifferently with every other -metal, but- it }s governed in 

 this respect by peculiar affinities ; thus, silver will hardly unite with iron, but it com- 

 bines readily with gold, copper, and lead. In comparing the alloys with their 

 constituent metals, the following differences may bo noted. In general, the ductility 

 of the alloy is less than that of the separate metals, and sometimes in a very remark- 

 able degree ; on the contrary, the alloy is usually harder than the mean hardness of 

 its constituents. The mercurial alloys or amalgams are, perhaps, exceptions to this 

 rule. 



The specific gravity is rarely the mean between that of each of its constituents, but 

 is sometimes greater and sometimes less ; indicating, in the former case, a closer 

 cohesion, and, in the latter, a recedure, of the particles from each other in the act of 

 their union. The alloys of the following metals have been examined by Crookewitt, 

 find he has given their specific gravities as in the following Table ; the specific gravity 

 of the unalloyed metals being 



Copper . . . 8794 



Tin . . . . 7-305 



That of the alloys was 



Cu 2 Sn 5 7-652 



Cu Sn 8-072 



Cu 8 Sn 8-512 



Cu 8 Zn 7-939 



Cu 8 Zn* 8-224 



Cu 2 Zn 8-392 



Cu* Pb 8 10-753 



Zinc. 

 Lead 



CuPb 

 SnZn" 

 SnZn 

 Sn s Zn 

 SnPb 2 

 SnPb 

 Sn 3 Pb 



. 6-860 

 . 11-354 



10-375 

 7-096 

 7-115 

 7-235 

 9-965 

 9-394 

 9-025 



The following Tables of binary alloys exhibit this circumstance in experimental 

 detail : 



Alloys having a density greater than the mean 



of their constituents. 

 Gold and zinc 

 Gold and tin 

 Gold and bismuth 

 Gold and antimony 

 Gold and cobalt 

 Silver and zinc 

 Silver and lead 

 Silver and tin 

 Silver and bismuth 

 Silver and antimony 

 Copper and zinc 

 Copper and tin 

 Copper and palladium 

 Copper and bismuth 

 Lead and antimony 

 Platinum and molybdenum 

 Palladium and bismuth 



Alloys having a density less than the mean of 



their constituents. 

 Gold and silver 

 Gold and iron 

 Gold and lead 

 Gold and copper 

 Gold and iridium 

 Gold and nickel 

 Silver and copper 

 Iron and bismuth 

 Iron and antimony 

 Iron and lead 

 Tin and lead 

 Tin and palladium 

 Tin and antimony 

 Nickel and arsenic 

 Zinc and antimony 



