ACTION OF POISONS. 135 



the strength of the oil, as a poisonous agent, 

 differs considerably. I suspect that the first 

 portion of the oil, which during distillation 

 passes into the receiver, contains more of the 

 poison than that which is obtained afterwards ; 

 arid that this explains why the oil which had 

 been prepared as an article of commerce was 

 much less active than that which had been spe- 

 cially prepared for the purpose of my experi- 

 ments. 



NOTE D. (Page 49.) 



The mode of death in which the cessation of 

 the action of the heart precedes the cessation of 

 that of the muscles of respiration, is not so 

 frequent as that in which the circulation con- 

 tinues after respiration has ceased. I found, 

 however, that some poisoned arrows brought 

 from Mozambique by the late Mr. Salt, pro- 

 duced death in the first of these two ways, 

 thus resembling in their effects the Upas 

 Antiar and the infusion of tobacco ; and Dr. 

 Christison has shown that the oxalic acid in a 

 diluted state has, when taken into the stomach, 

 a similar mode of operation. 



It is worthy of notice that when death is 

 suddenly produced by exposure to intense cold, 

 the phenomena which occur are very similar to 

 those which follow the exhibition of the above- 



& 4 



