Davy — On some Neio Organic Nitroprussides. 323 



then placed under a bell-glass along with a vessel of sulpliuric acid, 

 and the air exhausted, by which the further evaporation was readily 

 eif ected, and when the liquid portion was thus nearly all removed, the 

 crystals were drained, placed on filtering paper, and afterwards 

 exposed to the air for some hours ; and when they appeared to be 

 thoroughly dried, the salt was taken for examination. The crystals so 

 prepared were of a reddish-brown colour, and theii* form that of four- 

 sided prisms, some of which terminated in wedge-shaped ends, but 

 most of them abruptly, as if broken across. A given quantity of the 

 salt was then taken, and heated in the water-bath till its weight 

 became constant : by this treatment the crystals became more or less 

 opaque and friable, so that they were easily reduced to powder, though 

 they retained their external form. I found that the amount of 

 water lost in this way, and the quantity of silver nitroprusside 

 yielded by a given weight of the thoroughly-cbied salt, agreed most 

 closely with the quantities of water and of silver nitroprusside 

 which should be furnished by calculation, from a salt of morphine 

 having the formula (CnHigK'O,)-, H, (jSrO)FeCy5 + HoO, where two 

 molecules of the base were combined with one of the acid, plus 

 one atom of water of crystallization. It is consequently a neutral 

 salt in its constitution, and its solutions also indicate its neutrality. 

 The salt appears to undergo no change by exposure to the air, its 

 crystals having retained their form and appearance after long exposure 

 to its action. This nitroprusside dissolves slowly in cold water, but 

 readily in hot ; and, from an experiment I made, I ascertained that it 

 required about 112 times its weight of the former for its solution. It 

 dissolves slowly in rectified spiiit, especially at the ordinary tempera- 

 ture ; and is only very slightly soluble in ether and in chloroform. 

 Before leaving this salt I should observe that it may also be readily 

 obtained by treating a solution of morphine chloride with an excess of 

 silver nitroprusside, when the morphine nitroprusside and the silver 

 chloride will be produced, and the former, which remains in solution, 

 is easily removed from the latter, as well as from the excess of silver 

 nitroprusside that may be present, by filtration. 



I may further add that, from some experiments I made, it does 

 not appear that nitroprussic acid is capable of forming an acid salt 

 with morphine. 



Nicotine Nitroprussides. 



Mcotine (the active principle of tobacco, which is one of the most 

 deadly of our poisons, and, like prussic acid, will destroy life with 

 great rapidity when taken even in very small doses) is capable, I find^ 

 of forming two salts with nitroprussic acid, viz., a neutral and an acid 

 one. As the neutral salt does not appear to be crystallizable, Avhilst 

 the acid one is readily so, the latter possesses the most interest, aud 

 consequently was the one I chiefly studied. 



It may be easily obtained by adding to an aqueous solution of 

 nicotine nitroprussic acid till the mixture has a strong acid reaction 



2 L -i 



