Du Mez—The Galenical Oleoresins. 
1079 
which this constant was observed to be considerably lower. The 
low refractive index found for two of the commercial samples 
was very likely due to the fact that they contained twice as 
much volatile matter (principally essential oil) as the laboratory 
preparations. The effect of this influence, together with that 
produced by the presence of unevaporated solvent, is brought 
out in the following tables: 
Table 68. — Refractive indices of the oleoresins prepared in laboratory. 
Sample 
No. 
Date 
Observer 
Solvent 
Refractive 
index 
1.. 
i?i6 
DuMez . 
Alcohol. 
At 25° C 
1.520 
1.517 
1.517 
1.518 
1.517 
1.501 
2. 
Acetone... 
8. 
tt 
4.. 
44 
“ 
5......... 
Ether... . . 
6. 
Petrol, ether. 
Table 69. — Refractive indices of commercial oleoresins. 
Sample 
No. 
Date 
Observer 
Source 
Refractive 
index 
1 ... .... 
1916 
DuMez .. 
Squibb & Sons. 
At 25° C 
1.501 1 
2.. 
Sharp & Dohme. 
1.505 
8 ... 
44 
“ 
Lilly & Co . 
1.512 
. 
1 Contained ether. 
Chemical Properties. 
Loss in weight on heating: The oleoresins prepared in the 
laboratory lost, as a rule, between 11 and 13 per cent, of their 
weight on heating at 110° C, whereas the loss in the case of the 
commercial samples was about twice as great. While this dif¬ 
ference may have been due to the employment of different 
methods in the making of these preparations (a vacuum pan 
having probably been used in the removal of the solvent in the 
case of the commercial products), it is more likely the re¬ 
sult of the presence of a greater amount of volatile oil in the 
drugs from which the latter were prepared. The loss in weight 
