311 



colour, and the yellow solution produced contains the sulphate of 

 platinopyridine, which is extremely soluble in water, and dries up 

 into a gummy mass on evaporation. Considerable difficulties have 

 been encountered in obtaining the salts of platinopyridine in a 

 state fitted for analysis, and the only one which has given satisfac- 

 tory results is the chromate, which is obtained on adding bichromate 

 of potass to the sulphate, in the form of a fine orange-rod precipi- 

 tate, having the formula Cj„ H3 Pt N HO CrO^. 



When the bihydrochlorate of platinopyridine is boiled with two 

 equivalents of sulphate or nitrate of silver for a shorter time than is 

 requisite for its complete decomposition, and the chloride of silver 

 collected on a filter, washed and treated with ammonia, it leaves be- 

 hind a yellow crystalline matter, generally in small quantity. This 

 substance is insoluble, or nearly so, in water, but dissolves in boiling 

 nitric acid, from which it is deposited, on cooling, in beautiful shin- 

 ing plates. It contains chlorine, but I have not yet succeeded in 

 explaining its constitution. 



The golden yellow scales produced when the ebullition of the pla- 

 tinum salt of pyridine is stopped before the change into platino- 

 pyridine is complete, have a very singular constitution, the analysis 



10000 533-9 



and its formula is — ■ 



Cio Hj N H CI Pt CI2 + Ci, H3 Pt N 2H CI, 



representing it as a double compound of the original platinum salt 

 and the bihydrochlorate of platinopyridine. I refrain at present 

 from discussing its nature. 



When the platinum salt of pyridine is boiled with an excess of 

 pyridine, the fluid becomes extremely dark-coloured, and on evapo- 

 ration to dryness in the water-bath and addition of water, a dark 

 solution is obtained, and a crystalline residue left, which is very spa- 

 ringly soluble in water, more so in boiling alcohol, and is deposited 



