158 



KEPOET — 1881. 



The results for the prisms of borax agree very -well with one anothei-, 

 the greatest difference being "0006, and the mean •2120 may therefore be 

 taken as the specific refraction of fused borax. The mean of the values 

 obtained for borax dissolved in water is ^2112, which diffei-s from the 

 value obtained for the solid by •0008 ; the greatest difference, however, 

 exhibited by these numbers being '0174. 



IV. Fused horic acid in the solid state and in solution. 



Prisms of boric acid were cast in a similar manner to those of borax ; 

 and their refractive indices and specific gravities determined in the same 

 manner. The aqueous solutions were prepared with portions of the boric 

 acid used to make the prisms. 



The results obtained are contained in the following table : — • 



Comparing the mean of the specific refractions of the two prisms, viz., 



'21:51, with the mean of the values obtained for boric acid dissolved in 



water, viz., "2442, the latter is seen to be 0009 greater in the former. 



' This specific gravity is the mean of the determinations for the other two prisms. 



