540 LIQUID PARTS OF ANIMALS. 



and occasionally spurts to a considerable distance. Dr Davy 

 found it possessed of the following properties : 



The greater part of it is soluble in alcohol and water. The 

 aqueous solution is slightly viscid, and does not pass easily through 

 a common filter. It is not precipitated by acetate of lead, and 

 only very slightly by corrosive sublimate. When the aqueous 

 or alcoholic solution is evaporated to dryness, it leaves a yellow 

 transparent substance, having a slight but peculiar smell, and a 

 slightly bitter and very acrid taste, acting on the tongue like the 

 extract of aconite prepared in vacuo. It even occasions a smart 

 sensation when applied to the skin of the hand, and its effect 

 lasts two or three hours. When heated it readily melts, burns 

 with a bright flame, and does not emit an ammoniacal smell. It 

 neither reacts as an acid nor an alkali. Caustic ammonia dissolves 

 it. The solution remains acrid. Nitric acid also dissolves it, 

 and the solution has a purple colour. When neutralized by an 

 alkali the solution is but slightly acrid, and seems to have un- 

 dergone partial decomposition. 



Dr Davy conceives that the small portion of the poison of the 

 toad which is insoluble in water and alcohol, is a variety of albu- 

 men. But he does not state the reasons on which this opinion is 

 founded. 



Notwithstanding the acridity of this substance, it would appear 

 from Dr Davy's experiments that it is not injurious when intro- 

 duced into the blood. A chicken punctured with a lancet dipt 

 in it received no injury. Dr Davy says that he detected a not- 

 able quantity of it in the bile of the toad, in the viscid liquid lu- 

 bricating the tongue, and in the blood and urine of the animal. 

 But he does not mention the characters by which its presence in 

 these liquids was recognized. 



Dr Davy conceives that this liquor, (the venomous nature of 

 which does not seem well established by his experiments,) may 

 serve to protect the animal from the attacks of carnivorous ani- 

 mals. He thinks also that its secretion may contribute to the 

 discharge of carbon from the blood; and conceives that this 

 opinion is strengthened by a peculiarity in the distribution of the 

 pulmonary artery, which he describes. 



The poisonous liquid of the toad had been subjected to expe- 

 riment by M. Pelletier in 1817.* His results agree, on the 



* Jour, de Pharmacie, iii, 537. 



