144 



The accompanying table will give the results: 



The results show that all brands act very much alike. When dried 

 on glass there is a triMi> shi'iiikage. Tlic inonnted pliotograplis show cou- 

 sideral)U' ('xi>ansion and in every case a larger amount in one direction 

 tlian in tlie other. In some cases the per cent, of expansion is ten times 

 that in tbe other direction. 



