1818.] the Commencement of the Year 1817. Part I. 19 



together in a platinum crucible a mixture of ammonia-muriate of 

 platinum, sulphur and carbonate of soda, in the proportion of 

 equal weights of each ; by heating together one part of ammonia- 

 muriate of platinum and two parts of sulphur in an earthen 

 crucible ; and by heating together one part of platinum in a 

 very fine powder and two parts of sulphur. 



Sulphuret of platinum thus prepared has the form of black, 

 brilliant needles. When heated in the open air it loses from 

 15 to 16-i- per cent, of sulphur. We may, therefore, consider it 

 as a compound of 



Platinum 84 105 



Sulphur 16 2-0 



100 



When heated in close vessels, this sulphuret undergoes no 

 further change than a kind of fusion. The simple acids do not 

 attack it. 



When a current of sulphureted hydrogen gas is passed through 

 a solution of platinum in an acid as neutral as possible, a black 

 powder falls, which, when made thoroughly dry, still retains a 

 portion of water, which it gives out at a strong heat, along with 

 some sulphurous acid, and then a sulphuret remains similar to 

 that formed by the dry way. 



When the solution of platinum in nitromuriatic acid is exposed 

 to heat, a submuriate of platinum is obtained, which is insoluble 

 in water, and which is decomposed by potash or soda, leaving a. 

 black oxide, containing, according to the analysis of Vauquelin, 

 between 15 and 16 per cent, of oxygen. Thus it nearly agrees 

 in its composition with the sulphuret ; whereas the other 

 metals combine with twice as much sulphur as they do of 

 oxygen. — (Ann. de Chim. et de Phys. v. 260.) 



These experiments, compared with those of Berzelius, Edmund 

 Davy, and Cooper, demonstrate the imperfect state of our 

 knowledge of the oxides of platinum. 



8. B)*ass. — M. Chaudet had occasion to analyze three speci- 

 mens of brass. The first was very ductile, and much esteemed 

 for those articles that required hammering ; but it was not easily 

 turned on the lathe. The other two possessed much less ducti- 

 lity ; but answered very well for those articles that required to 

 be turned on the lathe. The result of his analyses was as 

 follows : 



First specimen. Brass made at Romilly. 



Copper 70-10 



Zinc 29-90 



Tin Trace 



b2 



