34 PHYSICOCHEMICAL PROPERTIES 



solutions are given to a series of animals, the apparent toxicity 

 of these products diminishes as their alkalinity increases. 

 Thus the rapid intravenous injection of 5 eg. of mono- 

 sodium luargol will kill a rabbit in a few minutes while an 

 injection of 40 eg. of the same disodium product or a little 

 hyperalkaline will not kill the rabbit. Moreover, it is not 

 the addition of the soda which has rendered this product 

 less toxic because monosodium compounds are ordinarily less 

 toxic than the disodium, provided the injections are made 

 in minutes rather than in some seconds. 



We must conclude, therefore, from this primary series of 

 experiments that the rapid death of an animal by no means 

 indicates the degree of toxicity of a product but this rapid death 

 may be a phenomenon of some other nature. 



In order to understand the causes of this rapid death it 

 has been necessary to undertake other experiments and 

 especially to study more closely the physicochemical proper- 

 ties of the arsenobenzenes as well as the transformations 

 which these products undergo "in vitro" and "in vivo." 

 When we seal in a series of tubes, various solutions of sodium 

 luargol of different degrees of alkalinity in very pure distilled 

 water we find that these solutions remain for a long time 

 perfectly clear and when we expose them to the air and to the 

 light, they undergo no alteration for several minutes. On 

 the other hand, if instead of dissolving these products in 

 distilled water the solutions are prepared with salt solution 

 (6 to 10 per thousand of sodium chloride) we find that the 

 monosodium compounds precipitate in a few minutes; the 

 disodium in a few hours; the hyperalkaline in a few days. 

 Other salts, especially those of calcium are still more active 

 in this regard. 



The rapidity with which a precipitate is formed in vitro 

 in salt mixtures coincides perfectly with the apparent toxicity 

 of the solutions and when an autopsy is made on an animal 

 which has succumbed in a few minutes to a large dose of one 

 of these solutions, precipitates are easily found in the heart 

 and in the pulmonary vessels as well as numerous infarcts in 

 all the tissues and organs. (Ch. Fleig, "Toxicite du Sal- 

 varsan.") 



