235 



PLYMOUTH INSTITUTION. 



PROCEEDINGS IN THE ATHEN^UM. 



February 26th. — Mr. Swain's Lecture on Poisons. 



The lecturer commenced by observing that there existed many 

 peculiarities about the constitution of poisonous substances; that 

 many differed in their component parts from nutritious bodies, 

 only in the most trifling degree, and enumerated several substances 

 in illustration. 



He stated that vegetables often produced poisonous secretions, 

 whilst themselves were salutary articles of diet; and vice versa. 

 That the poison of the rattle snake was certain death if inserted 

 into a wound, but might be swallowed with impunity. 



The lecturer, having dismissed the constitution of poisons, 

 commented on their operation. He said that we were unable to 

 say in what lay their power of action or how they antagonized the 

 vital principle. He briefly described the intestinal canal, adverted 

 to its large nervous supply, and stated that there were two theories 

 propounded to explain the destructive impression made by poisons 

 on the human body. One supposed the actual entrance of the 

 substance into the veins, and its actual contact with the brain. 

 The second ascribed the operation of poisons to their effect upon 

 the sentient extremities of the nerves, which effect was conveyed 

 along the nervous trunks to the centre of feeling. 



The lecturer believed that the latter was the correct explanation, 

 and illustrated it by diagrams and descriptions, taken from the 

 work of Messrs. Morgan and Addison, on poisons. Mr. Swain 

 next proceeded to comment on the criminal administration of 

 poisons, and on the art of secret poisoning, which, in the early 

 times of science, he believed might have been carried to a very 

 great extent. He however disbelieved entirely the assertion that 

 there existed poisons, which would destroy the victim at any given 

 time after their exhibition, at the will of the poisoner. The 

 lecturer thought that secret poisoning must be gradual ; and that 

 the only way in which it could be effected, was by the use of 

 repeated small doses of some deleterious substance. 



Mr. Swain adverted to the Aqua Toffana, so celebrated in 

 Italy during the nineteenth century, and thinks that arsenic was 

 the principal ingredient. He named other secret poisoners, and 

 stated that there existed at the sacred well of Temzem, in Mecca, 

 a salaried poisoner, who destroyed any one obnoxious to the 

 sultan, by infusing poison in the water of that sacred spring. 



Mr. Swain next commented on such of the poisons as were of 

 general interest, from their being resorted to as instruments of 

 suicide or murder : — arsenic, prussic acid, and opium were the 

 principal. 



