Equilibrium in the Dissociation of Precipitates. 41 



any causal relation between the two pathological processes 

 exemplified in this instance is a point upon which we have in- 

 sufficient data for a positive statement. 



A more detailed account of the case will be published later. 



26 (1090) 



Equilibrium in the precipitation reaction. 



By Richard Weil. 



[From the Department of Experimental Medicine of Cornell 

 University Medical College.] 



On the basis of experiments performed with horse serum, 

 and similar antigenic substances, it has long been held that 

 precipitation produced by antigen and antibody never goes on 

 to completion, but that both factors are always present in the 

 supernatant fluid. This has been explained by some as an in- 

 stance of the law of mass action, by others on the basis of certain 

 analogies of colloidal chemistry. 



If a pure substance, such as crystalline egg albumen, separated 

 by Hopkins's method, be used as antigen, the results are quite 

 different. When mixed in proper proportions with its antiserum 

 a precipitate is formed; the supernatant fluid never contains 

 both reactive substances. The results hitherto obtained are due, 

 therefore, to a fallacy of technique, and are traceable to the pres- 

 ence of multiple individual antigens in the antigenic substance 

 employed, with a corresponding multiplicity of antibodies in 

 the antiserum. 



27 (1091) 



Equilibrium in the dissociation of precipitates. 



By Richard Weil. 



[From the Department of Experimental Medicine of Cornell 

 University Medical College.] 



Chickering found that sodium carbonate extracts of a precipi- 

 tate, produced by a mixture of pneumococcus substance and its 

 antiserum, contained agglutinating and protective antibody, but 



