238 On the Comlination of Antimony tvkh Tin. 



of tin and antimony which constitute them. All of them 

 are not prccipiLatcd from their solution in the nitro-murialic 

 acid by means of water. There are, necessarily, limits ; but 

 these limits are very distant. It is necessary for the alloy 

 to contain one-third of its weight of antimony to have this 

 property, particularly if the excess of acid has been in a 

 great measure driven off by evaporation. I ought, however, 

 to notice that the precipitation is not completely made in 

 ■less than 24 hours, when antimony predominates; because 

 then the latter portions, which are a combination of the 

 two oxides with the muriatic acid, only separate by little 

 and little. 



This is not, however, the only example we have of com- 

 binations of oxides. We cannot doubt that the oxide of 

 tin docs not combine with the oxide of lead ; for on cal- 

 cining an alloy of three or four parts of lead and one part of 

 tin, it soon burns in the manner of apyrophorus, and is con- 

 verted all at once Into oxide ; while tin, much more com- 

 bustible than lead, far from prei^enting this sort of phseno- 

 menon, does not transform itself into putty but after a 

 long time, even by multiplying its points of contact with the 

 air. I made several other trials in order to ascertain if the 

 oxide of antimony would act upon other oxides as well as 

 upon the oxide of tin. I think I ascertained that the latter 

 is the only one which the antimonial oxide takes with it in 

 precipitation, and that the oxide of bismuth does not preci- 

 pitate any oxide along with itself, not even the oxide of tin. 



After having thus proved synthetically that my alloy was 

 formed of tin and antimony, I proceeded to inquire after 

 the analytical means proper to produce the separation of 

 these two constituent principles. I then employed the 

 muriatic acid, which dissolves tin very well, and docs not 

 attack the oxide of antimony. It had hardly any ac- 

 tion upon the alloy ; and, besides, in the portion dissolved 

 I found antimony. I next tried sulphurated hydrogen. I 

 knew that it would easily precipitate the muriate of an- 

 timony; and that, on the contrary, it would not decom- 

 pose but with difficulty the highly oxidated muriate of 

 tin. This method had no more success than the former. 



TIk; 



