144 



The accompanying table will give the results: 



The results show that all brjinds act very mui-h alike. When dried 

 on glass there is a tritle slirinkage. Tlie mounted irii()tograi)hs show con- 

 sideralile expansion and in every case a larger amount in one direction 

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

 tliat in tile other direction. 



