104 | ~ ORD. LI. Gramina. TRITICUM HYBERNUM. 
by the calico printers, and commonly called British gum. The most delicate 
test of the presence of starch is iodine, which renders its solution in water, 
even when largely diluted, of a beautiful blue colour. From the products 
obtained by distilling starch per se, it appears to be a ternary compound of 
oxygen, carbon, and hydrogen. According to the analysis of MM. Gay 
Lussac and Thenard, 100 parts of starch consist of 49,68 oxygen, 43,55 
carbon, 6,77 hydrogen. 
In this country, starch is manufactured exclusively from wheat-flour and 
potatoes; in .the West Indies, from the Jatropha Manihot, which is the 
well known substance, called arrow-root.* Starch is not absolutely identi- 
cal, as obtained from different vegetables. | According to M. Planche, the 
specific gravity of flour-starch to potatoe-starch is as 62 to 84, and this diffe- 
rence is not unimportant in pharmacy, as the former serves admirably to 
suspend camphor, and the latter is unfit. Gluten is a tough, fibrous, elastic 
substance of a greyish colour; it is almost tasteless, and bears a considerable 
resemblance, both in its properties and composition, to the peculiar animal 
principle, named jfibrine. When dried, it becomes semi-transparent, and 
somewhat resembles glue. It is dissolved by the alkalies and acids; the 
latter, when strong, decomposing it at the same time. 
M. Jaddei has “ ascertained, that the gluten of wheat may be separated 
into two distinct proximate principles, which he has distinguished by the 
names gliadine and zimome. They are obtained by kneading newly prepared | 
gluten, in successive portions of alcohol, until it is no longer rendered milky 
by the addition of water. The alcoholic solution being allowed to evapo- 
rate spontaneously, a small portion of gluten is at first deposited, and the 
gliadine remains behind, of the consistence of honey, and mixed with a little 
yellow resinous matter, from which it may be freed by digestion in sulphuric 
ether. The portion of the gluten not dissolved by the aleohol, is the zimome.” 
Gluten appears to be one of the most nutritive of vegetable substances; hence 
the superiority of wheat to all other grains as an article of nourishment. 
Medicai Properties, &c. Bread, as a remedial agent, is only used as -an’ex- 
ternal application in the form of poultice, or as a medium to increase the 
bulk, and give form to very active medicines—as in pills. When toasted, 
i. Sago, Tapioca, Salep, and Cassava, are all varieties of starch ; the former is obtained 
from the pith of some species of palms, and from Cycas circinalis. Salep is prepared from 
the bulbs of the orchis mascula; Tapioca and Cassava from the Jatropha Manihot. 
