320 Proceedings oftlie Royal Irish Academy. 



remaining some time longer, became somewhat opaque, and presented 

 a more or less crystalline appearance, which, when examined under 

 the microscope, was found to consist of masses of minute, flattened, ob- 

 lique prismatic crystals, the forms of which, however, were very 

 different from those of the neutral salt. Some of this nitroprusside, 

 which had assumed the crystalline condition, was washed with a little 

 distilled water, and dried, and the amount of silver nitroprusside which a 

 given weight would furnish ascertained. This was found to correspond 

 almost exactly with the quantity of silver nitroprusside which a salt of 

 the following composition should yield: — C2oB[24No02.H2(!N'0)EeCy5. 

 It has an acid reaction, and is much more soluble in water than the 

 neutral salt, requiring only about 107 times its weight at the ordinary 

 temperature for its solution, and when so dissolved it gives to the water 

 a reddish-brown colour. It also readily dissolves in rectified spirit, 

 especially on the application of heat. In its composition and proper- 

 ties it is, therefore, a perfectly analogous salt to the quinine acid sul- 

 phate. This salt, like the neutral one, on exposure to the air, loses 

 more or less of its water of crystalKzation. 



Cinchonine Nitroprussicles. 



Cinchonine, like quinine, forms two salts with nitroprussic acid. 

 The neutral one was obtained from cinchonine neutral sulphate, as in the 

 case of the quinine salt, only that in this instance, owing to its greater 

 solubility, a cold saturated solution was employed instead of a hot 

 one. On adding sodium nitroprusside to such a solution of cincho- 

 nine, an immediate reddish-white precipitate was formed, which, 

 when examined under the microscope, presented the appearance of 

 minute oil-like globules : these, on agitation, agglutinated into lumps, 

 which stuck to the sides and bottom of the glass in a resinous form, 

 and acquired a darker reddish colour. These masses, on standing till 

 the next clay, became crystalline, and small reddish-brown crystals, 

 which were peculiar compound modifications of the cube and octahe- 

 dron, were found floating on the surface of the liquid and adhering to 

 the sides of the glass containing the mixture. This salt, after drain- 

 ing and washing with a little distilled water, was dried, and the 

 amount of silver nitroprusside which a given quantity would yield ascer- 

 tained : this was found to agree very closely with that which should be 

 furnished by a salt having the following formula : — (C20II24N2O)'*. 

 IIo(]N'0)EeCy5. It is therefore a neutral salt, agreeing in its constitu- 

 tion with the corresponding quinine salt. This salt is soluble in about 

 192 times its weight of cold, and in about 35 times its weight of boil- 

 ing, water, and it readily dissolves even in cold rectified spirit. "When 

 this neutral salt was dissolved in nitroprussic acid it yielded an acid 

 cry stalliz able salt, which, no doubt, has the composition of the corre- 

 sponding quinine acid salt. 



