On Accidental Double Refraction in Liquids. 525 



component rays. A number of solutions of gelatine were 

 examined. In all cases the tubes were surrounded by ice. 

 The following tables give typical results, the light being red, 

 781 fifi to 639 fifi. 



I. *5 gm. in 100 c.c. having been on ice for 16 hours. 

 Compression in mm. 



•5 -4-48 



1-0 -15-12 



1-5 -22-12 



2-0 -33-65 



2-5 ? 



The depolarization prevented further observations. 



II. *5 gm. in 100 c.c, after being 18 hours on ice. 



Compression in mm. 



•5 +5-04 



1-0 8-96 



1-5 11-20 



2-0 9-25 



2-5 ? 



III. *5 gm. in 100 c.c, after being 48 hours on ice. 



Compression in mm. 



( -5 4-3-92)? 



1-0 11-76 



1-5 16-80 



2-0 25-20 ? 



IV. '3 gm. in 100 c.c, after being 40 hours on ice. 



Compression in mm. 



0-5 +4-48 



1-0 7-28 



1-5 9-52 



2-0 8-96 



0-0 1-68 



V. '3 gm. in 100 c.c, after being 48 hours on ice. 



Compression in mm. 



0-5 -3-36 



1-0 6-16 



1-5 6-16 



2-0 6-16 



0-0 ? 



A solution of '2 gm. in 100 c.c. showed (only) a trace of 

 double-refraction after 48 hours on ice. A solution of *1 gm. 



