SOME VEGETABLE PROTEIDS. 137 



As the quantity of crystallized flax-seed globulin prepared 

 was not sufficient for an extended investigation of its rotary 

 properties, the specific rotation was determined for only a 

 single solvent, a 10 per cent sodium chloride solution being 

 chosen as the most available. A good basis was thus obtained 

 for comparing its rotary power with that of the other proteids 

 studied. 



Sodium-chloride Solutions. 



These solutions of flax-seed globulin had a rather strong 

 yellow color. They proved, however, to be fairly transpar- 

 ent to sodium light, so that the writer was able to use in the 

 polarimeter solutions that appeared quite opaque when in a 

 beaker. 



Three independent solutions of flax-seed globulin in 10 per 

 cent sodium chloride were made, and used in the polarimeter. 

 The crystals of the globulin used in the first solution (Solu- 

 tion 13) were somewhat imperfect, having been rounded and 

 broken during the processes of filtering and drying. They 

 were separated by dialysis from a 10 per cent sodium-chloride 

 extract obtained from the fat-free flax-seed meal by a second 

 extraction at 20 C.* The globulin used in the other two 

 solutions contained none but perfect crystals. Part of it was 

 extracted from the flax-seed meal by a 10 per cent sodium- 

 chloride solution at 20 C., and the rest was similarly ex- 

 tracted at 60 C. In both cases the globulin was precipi- 

 tated from the extract by dialysis. 



The results of the polarimeter observations and from drying 

 down are tabulated below. With the exception of the first 

 and last, the values found for the specific rotation agree well 

 within the limits of error, although they apparently decrease 

 with the percentage of globulin in solution. The table shows 

 clearly how the error in the mean value of (a) D is increased 

 when a weak solution is used: 



* With these were mixed some perfect crystals obtained by cooling from a 

 5 per cent sodium chloride extract at 60 C. 



