326 Proceedings of Royal Society of Edinburgh. [sess. 
caused by it. Un-ionized nitric acid must have been formed to a 
sufficient extent to coagulate the albumin. 
This experiment avoids the complication which ensues when a 
weak acid acts upon a salt of a strong acid with formation of an 
insoluble salt of the weak acid, e.g. the action of hydrogen 
sulphide on many metallic chlorides. 
Chemical Laboratory, 
University of Edinburgh. 
( Issued separately October 12 , 1906 .) 
