On some Comlmations of PlatineT, 269-' 



portion of oxygen in the oxide of platina. With this view 

 I made the following experiments. 



Exper'uncnt 1. — Into a retort of the capacity of about 

 40 cubical inches, one cubical inch of an aqueous solution 

 of muriate of platina was introduced; the retort was ex- 

 hausted of air, and filled with hydrogen gas. It was im- 

 mediately removed to a vessel of water, and the stop-cock 

 taken off; the absorption of the hydrogen, and the conse- 

 quent reduction of the metallic oxide were very gradual, 

 and it was not till after three days that the platina was all 

 obtained in the metallic state : when carefully collected, 

 and previously heated to redness, it weighed 7'8 grains. 

 The hydrogen actually absorbed, amounted to 8*8 cubical 

 inches ; the barometer being at 30'', and the thermometer 

 60^. Now, as tu o volumes of hydros2;en combine with one 

 of oxygen to form water ; the one half of the volume of 

 hydrogen absorbed, will indicate the quantity of oxygen 

 previously combined with the metal obtained. In this ex- 

 periment the oxygen in union with 7"8 grains of platina, 

 absorbed 8' 3 cubical inches of hydrogen. Hence that in 

 100 grains would require 112'82 cubical inches of hy- 

 drogen. 



For 7*8 : 8-8 :: 100 : 112-82. 



And 112-82 cub. inch, of hydrogen = 56-41 cub. inch, 

 of oxygen. According to Sir H. Davy lOO cub. inch, of 

 oxygen gas weigh about 34 grains. Hence, 100 grains of 

 platina will combine with IQ-l? grains of oxygen. 



For 100 : 34 : : 56-41 : l<)-17. 



And 100 grains of oxide of platina existing in the 

 iqueous solution of muriate of platina, will consist of 

 84 platina. 

 16 oxygen. 



100 

 Experiment '2. — This experiment was conducted in a 

 manner precisely similar to the above. The only difference 

 was, that the solution of platina in this case, contained a 

 much larger quantity of metal. 21-3 grains of metallic 

 platina were obtained, and 25' 13 cubical inches of hydro- 

 gen were absorbed. Barometer 30°; thermometer Gi^. 

 ny calculation it will be found that, in this experiment, 

 100 grains ol oxide of platina appear to consist of 



Plaiina 83-3 



Oxygen .... 16'5 



1000 



fri 



