128 VEGETABLE SUBSTANCES. 



pound of starch and water. Starch is not soluble 

 in alkohol. 



In the process of converting grain into malty the 

 starch or fecula is changed into sugar. It may 

 also be converted into sugar by boiling it with 

 diluted sulphuric acid. 



Starch consists of carbon, oxygen, and hydrogen. 



Gluten. — This principle is found in various vege- 

 table juices, but most abundantly in wheat flour. It is 

 separated from it by washing, with a stream of water, 

 a paste made of flour and water, at the same time 

 kneading it between the fingers. The water car- 

 ries off the starch gradually, leaving the gluten be- 

 hind. Gluten is insoluble in water, and is elastic 

 like elastic gum. It has no taste, and, when dried, 

 becomes hard and brittle. It considerably resem- 

 bles animal gluten, furnishing ammonia by distil- 

 lation. 



Fixed oil. — This is obtained by pressure from 

 certain seeds and fruits, as the olive, linseed, rape 

 seed, almond, &c. The fixed oils differ much ; 

 some being nearly solid, are called vegetable 

 butters. When expressed, they are generally mixed 

 with some mucilage, which occasions them to turn 

 rancid. They may be deprived of their colour by 

 charcoal. Fixed oils dissolve sulphur, and then 

 form balsams. They also dissolve phosphorus. 



Fixed oils are very combustible, and, when 

 strongly heated, yield olifiant and carburetted hy- 

 drogen gases. 



They form soaps by being combined with alkali. 

 The best soaps are made of olive oil and soda ; but 

 common soaps are made with the animal oils and 

 fat. 



Transparent soap is made by dissolving soap in 

 alkohol, and then concentrating the solution whicli 



