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 100 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. 



