MORBID POISONS. 36d 



arrest their decomposition without destroying it ; in the latter, all 

 the circumstances necessary for the completion, of their decom- 

 position are presented. 



The temperature at which water boils, and contact with alcohol, 

 render such poisons inert. Acids, salts of mercury, sulphurous 

 acid, chlorine, iodine, bromine, aromatic substances, volatile oils, 

 and particularly empyreumatic oils, smoke, and a decoction of 

 coffee, completely destroy their contagious properties, in some 

 cases combining with them or otherwise effecting their decompo- 

 sition. Now all these agents, without exception, retard ferment- 

 ation, putrefaction, and decay, and when present in sufficient 

 quantity, completely arrest these processes of decomposition. 



A peculiar matter to which the poisonous action is due, cannot, 

 we have seen, be extracted from decayed sausages ; and it is 

 equally impossible to obtain such a principle from the virus of 

 small-pox or plague, and for this reason, that their peculiar 

 power is due to an active condition, only recognisable by our 

 senses through the phenomena which it produces. 



In order to explain the effects of contagious matters, a peculiar 

 principle of life has been ascribed to them — a life similar to 

 that possessed by the germ of a seed, which enables it under 

 favorable conditions to develope and multiply itself. There cannot 

 be a more inaccurate image of these phenomena ; it is one 

 which is applicable to contagions, as well as to ferment, to animal 

 and vegetable substances in a state of fermentation, putrefaction, 

 or decay, and even to a piece of decaying wood, which by mere 

 contact with fresh wood, causes the* latter to undergo gradually 

 the same changes, and become decayed and mouldered. 



If the property possessed by a body of producing such a change 

 in any other substance as causes the reproduction of itself, witli 

 all its properties, be regarded as life, then, indeed, all the above 

 phenomena must be ascribed to life. But in that case they must 

 not be considered as the only processes due to vitality, for the 

 above interpretation of the expression embraces the majority of 

 the phenomena which occur in organic chemistry. Life would, 

 according to that view, be admitted to exist in every body in 

 which chemical forces act. 



If a body A, for example oxamide (a substance scarcely solu- 

 17* 



