310 



and especially for the obstinacy with which they resist the action of 

 oxidizing agents. 



When the platinum salt of pyridine, carefully freed from excess of 

 bichloride of platinum is dissolved in hot water, and the solution kept 

 steadily boiling for some hours, a fine sulphur yellow crystalline 

 powder begins to appear. After five or six days' continuous boiling 

 the whole of the platinum salt is converted into this substance, but 

 if the powder be filtered off before the change is complete, the 

 mother liquid on cooling gives a deposit of fine golden-yellow scales 

 resembling iodide of lead. 



The yellow powder is insoluble in water and acids, and is decom- 

 posed by potash slowly in the cold, more rapidly on boiling, with the 

 evolution of pyridine. It is the salt of a platinum base, analogous 

 to platinamine, to which I give the name of platinopyridine. Its 

 analysis gave — 



100-00 248-7 



It is therefore a bihydrochlorate of platinopyridine, with the for- 

 mula Cj(j Hg Pt N + 2 H CI, and the decomposition which yields it 

 consists simply in the expulsion of an equivalent of hydrochloric acid, 

 as represented by the equation 



Cj, H, N, H CI Pt CI = C , H3 Pt N + 2 H CI -f- H CI. 



The equivalent of hydrochloric acid escapes with extreme slowness, 

 but the change may be much facilitated by the addition of a sufficient 

 quantity of pyridine to combine with it, although an excess must be 

 carefully avoided, as it produces a different decomposition, to be after- 

 wards described. 



Platinopyridine cannot be separated from the bihydrochlorate 

 by alkalies, but when boiled with salts of silver, the corresponding 

 salts of the base are obtained. The decomposition, however, is very 

 slowly effected, and certain changes occur which I am not yet in a 

 condition satisfactorily to explain. When the hydrochlorate is boiled 

 with two equivalents of sulphate of silver, it gradually loses its 



