•322 Proceedings of the Royal Irish Academy. 



almost "wMte precipitate, which is amoii^hous, and its particles did not 

 agglutinate together like some of the other nitroprussides, •which do 

 not assume a crystalline form when so precipitated. It was very slow 

 in subsiding, though it was easily filtered and washed, the filtrate from 

 the first passing thi'ough clear : after washing, till it gave scarcely a 

 trace of sulphuric acid, it was dried and examined. In this state it 

 is almost white, and drfiers little in its appearance from veratrine itself. 

 It is sparingly soluble in both cold and hot water, requiring about 416 

 times its weight of water at the ordinary temperature, and about 215 at 

 the boiling point, for its solution. This nitroprusside, unlike most of 

 those of the other alkaloids, does not appear to have any disposition to 

 form a crystalline salt, even after long standing. I have not yet been 

 able to ascertain the proportion of base and of acid that it contains ; 

 but there can be little doubt that it consists of two molecules of the 

 base combined with one of the acid, as in the case of the neutral salts 

 of the other alkaloids. It is very soluble in rectified spirit, both cold 

 and hot ; and in ether it dissolves to a considerable extent, whilst in 

 chloroform its solubility is much less. 



From the experiments I made, it does not appear that veratrine is 

 capable of forming an acid salt with nitropmssic acid. 



Morphine Nitropruuide. 



I shall now describe a few of the nitroprussides of the alkaloids 

 which foiTu very soluble salts, and therefore cannot be obtained by 

 precipitation, as those already noticed. 



The very important alkaloid morphine, the chief active principle 

 of opium, forms a readily crystallizable neutral salt with nitroprussic 

 acid. It was obtained by simply dissolving, with the assistance of a 

 gentle heat, morphine^ in nitroprussic acid, till a perfectly neutral 

 solution was obtained. This, which was of a reddish-brown colour, 

 being filtered, and the filtrate somewhat concentrated by evaporation 

 on the water-bath, began to furnish prismatic crystals ; and in order to 

 obtain these of larger size and more perfect form, the solution was 



^ The nitroprussic acid used in fomn'ng tHs and other salts was easily prepared 

 by digesting for some days, with occasional agitation, silver nitroprusside in diluted 

 hydrochloric acid, contained in a well-stopped bottle ; when the nitroprussic acid 

 and silver chloride are formed by double decomposition, and the fonner may be 

 separated from the latter by filtering the mixture. In preparing thus this acid, it is 

 necessary to employ an excess of silver nitroprusside to ensure the complete re- 

 moval of the hydrochloric acid employed. That such is the case may be ascertained 

 by collecting some of the silver chloride, and this being well washed on a filter with 

 distilled water till the filtraTe becomes colourless ; if then, after the addition of a few 

 drops of diluted hydrochloric acid to the chloride, the water used in washing it 

 again acquires a reddish coloui", it is a proof that there was some silver nitroprusside 

 in excess over that necessary to remove the whole of the hydrochloric acid. Indeed, 

 if the silver chloride foiTQed, after being well washed, has a reddish colour, it indi- 

 cates the same fact. 



