526 On Accidental Double Refraction in Liquids. 



in 100 c.c. gave no effect after 48 hours. Two tubes con- 

 taining *1 gm. in 100 c.c. were then allowed to stand for 

 120 hours on ice with the following results : — 



VI. 



Compression in mm. 



0-5 -4-48 



0-0 -fO-56 



0-5 —5-04 



1-0 -5-04 



1-5 -5-04 



0-0 --28 



VII. '1 gm. in 100 c.c, after being 120 hours on ice. 

 Compression in mm. 



0-5 -5-32 



0-0 + -o6 



0-5 -1-68 



1-0 -3-64 



1-5 -3-92 



0-0 -2-24 



As stated previously these solutions behave as if they were 

 solids having a low elastic limit. When a stress is applied 

 the strain increases to a certain point beyond which no further 

 strain is produced, as shown in Tables V., VI., and VII. If 

 the distortion be carried further rupture takes place and the 

 strain diminishes, as shown in Tables II., IV., and V. 



The solid structure grows in time though not in proportion 

 to it, and not always with the same rapidity for solutions of 

 the same concentration. The growth is more rapid in the 

 more concentrated solutions. Frass* found that solutions 

 containing more than 7 per cent, of gelatine attained a maxi- 

 mum rigidity in from 24 to 32 hours, while the solution 

 containing '1 per cent, used in this experiment requires a 

 much longer time to attain a maximum rigidity. Along with 

 double refraction, depolarization also appeared. This was 

 very small at first, but in the case of a solution containing 

 *5 per cent, of gelatine it became so great in 24 hours as to 

 interfere seriously with the accuracy of observation. After 

 24 hours more it was again greatly decreased. This seems 

 to indicate that the structure does not grow uniformly 

 throughout the liquid, and so, at the end of the first 24 

 hours, it was not homogeneous. After the second 24 hours 

 there was greater homogeneity, and consequently a more 

 uniform strain and less scattering of the light. This may 



* Wied. Ami. vol. liii. p. 1074. 



