ON ALCOHOLTC TINCTURES. 
The preference ought, therefore, to be given to that degree 
of strength ; besides, five parts of the solvent being the pro- 
portion that gives the most extraet, that proportion ought to 
be adopted. 
II. RED BARK. 
grs. 
1 pt. or 15 gr. by 60 gr. or 4 pts. alco. at 80° total ext. of tine 1-97 
75. " 5„ " «- id. " 2-42 
90 " 6 " 44 id. " 2-37 
75 « 5 " " 75° " 2 05 
60 « 4 44 41 56° 44 1-98 
75 « 5 44 " id. « 2-31 
90 " 6 " id. . « 2-26 
75 " 5 " " 45° « 1-99 
QUANTITY OF THE ALKALOID. 
150 grs. of tinct. made with 1 pt. bark and 5 pts. alco. at 80° precip. 1-346 
150 " " " 56° " 1-594 
We perceive that, in contradiction to what took place in the 
case of yellow bark, alcohol at 56° dissolves more of the ac- 
tive principle than alcohol at SO. I therefore, prefer alcohol at 
56° : and as five parts give a larger quantity of extract than 
four, I adopt the proportion of five parts of that solvent. 
III. GRAY BARK. 
grs. 
1 pt. 15 gr. by 60 gr. or 4 pts. alco. at 80° total ext. of tinct. 2.69 
75 " 5 " 44 id. " 2-89 
« » 60 " 4 44 44 56° 54 3-2.1 
" " 75 44 5 44 44 id. 44 3-15 
90 44 6 44 44 id. 44 3-07 
75 44 5 44 44 45° 44 2.87 
QUANTITY OF ALKALOID. 
150 gr. of tinct. made with 1 pt. bark and 5 pts. alco. at 80° precip. 1-102 
150 gr. 44 " 44 56° 44 1-795 
These results are again the reverse of those obtained with 
yellow bark; here once more it is alcohol at 56° that dissolves 
most of the active principle. This experiment agrees with 
the result of M. Guibourt obtained in 1818, when the Codex 
of that year was edited, by ascertaining the action of alcohol 
at different degrees of strength on gray bark ; he found, in 
