338 POISONS, CONTAGIONS, MIASMS. 



indication of change can be detected by simple 

 observations of the parts, because, as has been 

 already remarked, death may occur without the 

 destruction of any organs. 



When arsenious acid is administered in solution, 

 it may enter into the blood. If a vein is exposed 

 and surrounded with a solution of this acid, every 

 blood-globule will combine with it, that is, will 

 become poisoned. 



The compounds of arsenic, which have not the 

 property of entering into combination with the 

 tissues of the organism, are without influence on 

 life, even in large doses. Many insoluble basic 

 salts of arsenious acid are known not to be poison- 

 ous. The substance called alkargen, discovered by 

 Bunsen, which contains a very large quantity of 

 arsenic, and approaches very closely in composition 

 to the organic arsenious compounds found in the 

 body, has not the slightest injurious action upon 

 the organism. 



These considerations enable us to fix with toler- 

 able certainty the limit at which the above sub- 

 stances cease to act as poisons. For since their 

 combination with organic matters must be regu- 

 lated by chemical laws, death will inevitably 

 result, when the organ in contact with the poison 

 finds sufficient of it to unite with atom for 

 atom ; whilst if the poison is present in smaller 

 quantity, a part of the organ will retain its vital 

 functions. 



