THE ASH OF PLANTS. 111 
acids. In the pure state it is a colorless, oily liquid, having the odor 
of tobacco in an extreme degree. It is inflammable and volatile, and so 
deadly that a single drop will kill a large dog. French tobacco contains 
Vor 8p. c.; Virginia, 6 or 7 p. c.; and Maryland and Havanna, about 2p. 
@. of nicotin. Nicotin contains 17.3 p. c. of nitrogen, but no oxygen. 
Caffein, C, Hy. Nz Os, exists in coffee and tea combined with tannic 
acid. In the pure state it forms white, silky, fibrous crystals, and has a 
bitter taste. In coffee it is found to the extent of one-half per cent; in 
tea it occurs in much larger quantity, sometimes as high as 6 per cent. 
Theobromin, C; H, N, O2, resembles caffein in its characters, 
and is closely related to it in chemical composition. Itis found in the 
eacao-bean, from which chocolate is manufactured. 
The alkaloids are remarkable from containing nitrogen, and from hay- 
ing strongly basic characters. They derive their aeetsCntOn alkaloids, 
from their likeness to the alkalies. 
CHAPTER IL 
THE ASH OF PLANTS. 
g§ 1. 
THE INGREDIENTS OF THE ASH. 
As has been stated, the volatile or destructible part of 
plants, 7. e. the part which i is converted into gases or vapors 
under the ordinary conditions of burning, consists chiefly 
of Carbon, Hydrogen, Oxygen, and Nitrogen, together 
with minute quantities of Sulphur and Phosphorus. 
These elements, and such of their compounds as are of 
general occurrence in agricultural plants, viz., the Organic 
Proximate Principles, have been already described in detail. 
The non-volatile part or ash of plants also contains, or 
may contain,’ Carbon, Oxygen, Sulphur, and Phosphorus. 
It is, however, in general, chiefly made up of eight other 
elements, whose common compounds are fixed at the ordi- 
nary heat of burning. 
