478 GOLD, PLATINUM, PALLADIUM, c. 



stance at my disposal being too small to enable 

 me to prosecute the subject to any extent. 



1. I mixed together equal weights of zinc 

 filings and osmium, and putting the mixture into 

 a glass tube benf like a retort, I poured on it a 

 quantity of dilute sulphuric acid, to see whether 

 the hydrogen gas evolved contained any osmium 

 in solution : but I could obtain no evidence that 

 it contained any. The gas had no sensible smell 

 nor taste ; it was not absorbed by water, and did 

 not produce any sensible effect upon the solu- 

 tions of lead. It burned just like common hy- 

 drogen gas, and required, as usual, half its 

 volume of oxygen gas for complete combustion. 



The sulphuric acid solution of the zinc was 

 black and opaque, and contained, obviously, a 

 portion of the osmium in a state of solution. 

 But upon attempting to obtain this triple solution 

 in a 'dry state, the colour gradually became 

 lighter as the evaporation advanced, and when 

 the whole had been reduced to dryness, all traces 

 of the presence of osmium had vanished. 



Osmium, in the metallic state, was digested in 

 caustic soda ley : a yellow coloured liquid was 

 obtained, but the greatest part of the osmium 

 remained undissolved. 



END OF VOLUME FIRST. 



