34 On the Comlinatiom of 



suits, was that employed to ascertain the composition of 

 the siipcr-sulphurttt by synthesis, and to this I had recourse. 



From several e.xpermients twO of the most accurate are 

 selected, from which its composition is deduced. 



First Experiment. 30 grains of the ammonia-muriate of 

 platina were heated with phosphorus in a small green glass 

 retort coated with clay, for about half an hour, during 

 which lime the retort had been heated to a dull red. The 

 super-phosphurct collected when the retort was cold, weighed 

 1895 grains. Now these 30 grains of the metallic salt 

 contained 13'35 grains of platina; consequently the IS'95 

 grains of super-j)hosphuret consisted of 13'33 grains of 

 platina -|-56 grains of phosphorus. This experiment indi- 

 cates 30 per cent, of phosphorus in the super-phosphuret. 



Second Experiment. 10 grains of the ammonia-muriate of 

 platina heated with phosphorus precisely in the same way 

 as the last experiment furnished 6"34 grains of super-phos- 

 phuret. This experiment very nearly agrees with the pre- 

 ceding one. And J 00 parts of super-phosphuret of platina 

 may be regarded as composed of Platina. ... 70 



Phosphorus 30 



100 

 7. Of Sub-Pliosphuret of Platina, 



This substance was obtained i)v heating together platina 

 and phosphorus in an exhausted tube, similar to that used 

 for procuring the sub-sulphuret of platina. The intensity 

 of their mutual attraction is beautifully demonstrated by 

 this experiment. At a temperature considerably below 

 redness, they combine with vivid ignition and flame, and 

 ■ unless the tubes are strong they are very liable to be de- 

 stroyed. 



Pity sical and Chtmical Properties. 



SuH-phosphuret of platina is of a lead gray, or blueish- 

 grav colour. It is either obtained in small porous masses, 

 or (in cases when as nuich as i?0 grains of the metal are 

 employed) in imperfectly fused and crystallized pieces. 

 The crystals are small cubes. When it has undergone 

 fusion its lustre i> litile inferior to that of lead, but in a 

 porous slate it has little brilliancy. 



Its specific gravity when in porous pieces is about 6. 

 After fusion ifiere can be no doubt but it nmst be consider- 

 ably more. It has no ta«te or smell. It is a non-conductor 

 of electricity. When it is heated to a strong red on a slip 



of 



