J820.] Philosophical Transaction for 1820, Part I. 385 



ovarium, and tore the adhesions of the placenta : this produced 

 the sudden haemorrhage which proved fatal. 



This case is undoubtedly curious. It is difficult to conceive 

 how impregnation was produced. Doubtless the changes in the 

 falopian tubes must have taken place at a subsequent period. 



VI. On some. Combinations of Platinum. By Edmund Davy, 

 Esq. Prof, of Chemistry, and Secretaiy to the Cork Institution. 

 — Sulphate of platinum is soluble in aJcohol and ether. If an 

 aqueous solution of this sulphate be mixed with alcohol, and set 

 aside for some time, a black powder precipitates, and the hquid 

 becomes colourless. The same black matter is obtained in a 

 few minutes by boiling together sulphate of platinum and 

 alcohol. 



This powder is black, in small lumps, which are soft, and 

 easily reduced to an impalpable powder. It soils the fingers or 

 paper, is destitute of lustre, tasteless, and insoluble in water 

 both cold and hot. It is not altered by exposure to the air. 

 When heated, a feeble explosion is produced, with a Hash of 

 red hght, and the platinum is reduced. It is insoluble in nitric, 

 sulphuric, and phosphoric acids ; but it dissolves slowly in muriatic 

 acid. It is scarcely affected by chlorine. When put into liquid 

 ammonia it gradually acquires fulminating properties. When 

 placed in contact v.'ith ammoniacal gas, it becomes red-hot and 

 scintillates. It is immediately decomposed by the agency of 

 alcohol. If a bit of paper, or cork, be moistened with alcohol, 

 and a little of the powder placed on it, a hissing noise is heard, 

 and the platinum is reduced and ignited, and continues in a state 

 of ignition till the whole of the alcohol is consumed. When the 

 powder is boiled in alcohol, it is partially decomposed, and 

 becomes hghter. If it be then thrown upon a filter, the odour 

 of acetic acid is perceived, and in a few hours the platinum is 

 reduced, and the paper charred. When mixed with flowers of 

 sulphur, and heated, a blue coloured sulphuret of platinum is 

 formed. This powder, according to the experiments of Mr. 

 Davy, is composed of 



Platinum 96-25 



Nitric acid, oxygen, and carbon 3-75 



100-00 



It is not easy to form a conception of such a compound. It 

 must of necessity be at least in part a mechanical mixture. 



Mr. Davy finds that sulphate of platinum is capable of preci- 

 pitating gelatine from its aqueous solution. He recommends it 

 as a test for that substance, and thinks it better and more deli- 

 cate and certain than the infusion of nutgalls. 



Mr. Davy described in a former paper a mode of preparing 

 grey oxide of platinum. The method is to add strong nitric acid 



Vol. XVI. N° V. 2 B 



