794 ACETYL. 



PtCl, or AcCl + PtCl. This compound is formed by the action 

 of bichloride of platinum upon alcohol, together with aldehyde,but 

 it is best prepared from a double compound, which it forms with 

 chloride of potassium or chloride of ammonium. Pure bichlo- 

 ride of platinum containing no free nitric acid is dissolved in 

 alcohol ; a small quantity of free hydrochloric acid, and a quantity 

 of chloride of potassium equal to one eighth of the weight of the 

 bichloride of platinum are added to this solution, and the whole 

 digested for several hours at the temperature of boiling water. 

 The excess of alcohol is removed by distillation, and the residue 

 saturated with carbonate of potash. By evaporating at a gentle 

 heat the compound in question is obtained in the crystalline form., 

 and maybe purified by new crystallizations. (Liebig's Traite). By 

 dissolving this compound in a little water and adding bichloride 

 platinum to the solution, so long as the double chloride of 

 platinum and potassium precipitates, a yellow liquid is obtained, 

 which ought to be evaporated in a dry vacuum in the absence 

 of light. There results a gummy mass of a honey yellow colour, 

 liable to be blackened by light, which is the chloroplatinate of 

 the chloride of acetyl. It dissolves slowly in water and alco- 

 hol ; these solutions have an acid reaction. The hydrochloric 

 acid of Dutch-liquid being represented by proto-chloride of 

 platinum, Pt Cl, the compound described and Dutch-liquid may 

 be considered as analogous : 



Chlorhydrate of chloride of acetyl. . . Ac Cl + H Cl. 

 Chloroplatinate of chloride of acetyl. . Ac Cl + Pt Cl. 



But various other views of the constitution of this compound 

 have been proposed. 



Chloroplatinate of chloride of acetyl and potassium,, Ac Cl, 

 Pt Cl + K Cl. The discovery of this salt, of which the prepa- 

 ration has just been described, is due to Berzelius. It crystal- 

 lizes in semi-transparent regular prisms, of a lemon yellow 

 colour, which abandon 4.625 per cent of water of crystalliza- 

 tion at 212 and become quite opaque. It is soluble in alcohol, 

 and also in 5 parts of hot water, and is less soluble in cold 

 water. The solution is partially decomposed when heated to 

 194, metallic platinum being precipitated and hydrochloric acid 



