igi2] William H. Welker 77 



bags^^ immediately, toluol slowly, whereas formic acid, formalde- 

 hyde (40 per cent.), Chloroform, petroleum ether, carbon tetra- 

 chlorid, carbon bisulfid and paraffin oil were without distinguishable 

 solvent action, even after long periods of contact. Acetone (5 per 

 cent.) in absolute ether attacks collodion bags slowly, while a 10 per 

 cent. Solution acts rapidly. Acetaldehyde (4 per cent.) in absolute 

 ether attacks the bags slowly, but a 5 per cent. Solution acts rapidly. 

 Methyl alcohol (3 per cent.) in absolute ether dissolves the bags, but 

 a 2 per cent. Solution does not. Glacial acetic acid (2 per cent.) in 

 absolute ether attacks the bags slowly, a 3 per cent. Solution acts 

 rapidly but a i per cent. Solution appears to be inert. Five per 

 cent. Solutions of Chloroform, toluol, petroleum ether, carbon tetra- 

 chlorid, carbon bisulfid, benzol, ethyl acetate, and paraffin oil, 

 in absolute ether, were without visible effect on collodion bags. 

 Five per cent. Solutions of formic acid (sp. gr. 1.2) and formalde- 

 hyde (40 per cent.), in absolute ether, immediately attacked and 

 penetrated collodion bags. 



Further work along these lines is in progress. 



My cordial thanks are due Dr. Gies for his kind direction and 

 assistance in these experiments. 



"Bags practically free from residual alcohol were used. 



