178 PLANT AND ORGANIC CHEMISTRY 
dried until in a state of powder; for all vegetable substances 
must be brought into fine subdivision before extraction, in 
order that the solvents may penetrate the cells. 
The fine powdering of the material is of the utmost impor¬ 
tance; a drug mill is usually used for this purpose. An agate 
or iron mortar may be used sometimes to advantage, or the 
material may be grated upon a fine grater, and then sub¬ 
mitted to the same process of powdering and sifting, until it 
can be passed through a No. 80 sieve. 
The Mexican ocotilla bark 1 is resinous and contains a wax, 
and it is very difficult to powder. From this fine powder the 
analysis yielded, by cold maceration, thirteen per cent, of waxy 
substance. Hot maceration gave nine per cent. An analysis 
from portions less finely powdered gave three per cent, less 
of wax. To estimate the amount of moisture retained in the 
air-dried plant, a small quantity of the powder, from two to 
five grams, may be weighed and dried until constant weight 
at a temperature from ioo° C. to 105° C. By means of this 
determination the results of all other estimations of the analy¬ 
sis can be calculated to the dry substance. Even in the case 
of fresh plants, it will be necessary for a quantitative exami¬ 
nation of the entire plant, at least to dry the portions which 
are to be treated with petroleum-ether, ether, and alcohol. 
The powder which has served for the moisture determination 
is carefully burned at a dull red heat, and the ash residue 
weighed. This gives the total ash constituents of the plant. 
In many cases it is desirable to estimate the amount of soluble 
and insoluble ash, and to determine, quantitatively, one or more 
of the ash constituents, especially sulphuric and phosphoric 
acids and potash. In the ash may be found phosphorus, sul¬ 
phur, silicon, chlorine, potassium, sodium, calcium, magne¬ 
sium, iron, and manganese, as well as oxygen, carbon, and 
nitrogen; rarely lithium, rubidium, iodine, bromine, fluorine, 
barium, copper, zinc, and titanium. The carbon, hydrogen, 
nitrogen, sulphur, and phosphorus are derived more especially 
from the organized parts of the plant, as the protoplasm and 
1 ‘‘Preliminary Analysis of the Bark of Fouquieria Splendens,” by Helen 
C. De S. Abbott. See p. 117. 
