CHAPTER II. 

 PHYSICOCHEMICAL PROPERTIES 



Transformations of the Arsenobenzenes "in Vitro" and in the Organism. 



THE discovery of the arsenobenzenes and especially of 

 their physicochemical and biological properties has opened 

 new horizons for the study of the transformation of anti- 

 gens. It has been recognized that certain arsenobenzenes, 

 more particularly arsenophenylglycin . and dioxydiamino- 

 arsenobenzene (salvarsan) or its compounds, mono- bi- or 

 trimetallic luargol or cupriluargol are colloids and may 

 cause the formation of specific antibodies under the same 

 conditions as the biologic antigens which we have studied 

 heretofore. These substances possess properties essentially 

 analogous to every other antigen. Let us see how it has been 

 possible to consider them in this way. 



The product which has been most particularly studied 

 from this point of view is dioxydiaminobenzene-antimonious- 

 silver-bromide (luargol) because it is a strongly colored 

 red-brown solution which allows us to follow it in its trans- 

 formations much easier than simple arsenobenzene or arseno- 

 phenylglycin, the color of which does not differ essentially 

 from that of serum or other organic fluids. Luargol is a 

 yellow powder more or less dark colored, insoluble in the 

 basic state but soluble when slightly acidified with hydro- 

 chloric, phosphoric or citric acid; insoluble as a sulphate, 

 but soluble as a sodium compound when made slightly 

 alkaline. 



The most convenient preparations for treatments and 

 experiments are the sodium compounds and monosodium 

 or disodium solutions can be obtained as well as intermediary 

 'alkalies between these two limits as well as hyperalkaline 

 solutions. 



When intravenous injections of these different alkaline 

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