[ 152 J 

 XYIII. Intelligence and Miscellaneous Articles. 



OS SOME EXPLOSIVE ALLOYS OF ZINC AND THE PLATINUM 

 METALS. BY H. SAINTE-CLAIRE DEYILLE AND H. DEBBAY. 



Q OME time before the sickness of my dear and illustrious master 

 ^ Henri Samte-Claire Deville, we had undertaken to return to 

 some points in order to complete our old researches respecting pla- 

 tinum. Our work, as regards the division of the osmides, was 

 almost finished, when it was interrupted by his sickness and death. 

 I have had to terminate it ; and today I present the result to the 

 Academy. 



It is known that the osmides cannot be divided by mechanical 

 action. If for example, one essays to pound them in a tempered 

 steel mortar, the osmide of iridium penetrates into the material 

 without being either blunted or broken. 



If, however, it be fused with 25 or 30 times its weight of zinc, 

 and if after the mixture has been kept for some hours at an 

 incipient red heat it then be more heated in order to volatilize all 

 the zinc, there remains a spongy mass, easily divided, and, in this 

 state, completely and with facility attacked by the mixture of 

 nitrate and binoxide of barium which we have employed for 

 oxidizing the two metals of the osmide and to render them soluble 

 in acids. As it is easy to eliminate baryta from its solutions, the 

 anal y sis of the osmide then becomes possible. 



What is the part played by zinc in this division? by what 

 mechanism is it effected ? are questions which we had not then 

 examined, contenting ourselves for the moment with a practical 

 result sought in vain by Berzelius, which facilitated our entering 

 upon that study of the platinum metals which has occupied us for 

 many years. 



I. Some osmide of iridium is thrown into some zinc heated to 

 dull redness and which has been previously well cleaned with sal- 

 ammoniac. A brisk disengagement of heat is produced. The 

 mass is kept melted at this temperature during five or six hours, 

 in order to attack completely the large grains of osmide. The 

 cold button is then dissolved in dilute hydrochloric acid. The 

 solution of the zinc takes place with great violence ; and there 

 remains a blackish residue having the appearance of graphite, 

 which contains all the noble metals of the osmide. The greater 

 part of the iron existing in this material is dissolved at the same 

 time as the zinc ; on the other hand, there remains a notable 

 proportion of zinc combined with the metals of the osmide, and it is 

 not removed by prolonged contact with concentrated hydrochloric 

 acid. 



This residue, well washed, and dried at 100°, diffuses in the air 

 a slight odour of osmic acid. Heated to nearly 300° it suddenly 

 ignites, almost with explosion, spreading fumes of zinc and abun- 

 dant vapour of osmic acid. As this deflagration took place in vacuo, 

 without any sensible liberation of sas, and of course without the 





