40 BOTANY. 



Sugar occurs in many species of plants, and appears under three 

 principal forms : cane sugar, grape sugar, and mannite. Cane sugar, 

 C, IP, 0^ + 2H0, is obtained from man}^ plants, as sugar cane, beet root, 

 sugar maple, birch, &c. It is soluble in about one third of its weight of water, 

 and insoluble in pure alcohol. Grape sugar, or glucose, C"^, H"', 0"* + 2H0, 

 is found in grape and other juices. It can be prepared from starch or cane 

 sugar by boiling in dilute sulphuric acid. Mantiite, C^ H^, 0*, the chief 

 ingredient of manna, a substance derived from several species of ash, differs 

 from the others in not undergoing the vinous fermentation. It is also found 

 in the juices of celery, mushrooms, &c. 



LiGNiNE occurs abundantly in woody fibre, and is distinguished from 

 cellulose in being soluble in strong nitric acid, forming oxalic acid. Its 

 formula is C^^, H*^, 0*^". All these substances are readily convertible into 

 each other. Some other ternary compounds of this character are salicine, 

 found in the willows, and phloridzine, obtained from the bark of the roots of 

 the apple, »fcc. 



There arc other vegetable products which differ from these last in the 

 presence of nitrogen. Thus gbiten is that part of wheat flour which 

 remains after the removal of the starch. Vegetable fihrbie is obtained by 

 treating the glutinous part of wheat with ether. Vegetable cascine, or 

 legumine, is found in oily seeds, and in leguminous plants. Vegetable albumen 

 occurs as a soluble substance with caseine. It coagulates at a temperature 

 of 140° to 160° F., and is not precipitated by acetic acid. The base of all 

 these substances is proteine (C^", H'', N*, 0""^) Fibrine is proteine 

 + S + PA. Albumen is proteine + S^ + Pa. Caseine is proteine + S, 

 Emulsine, or synaptase, is found in almonds : and in bitter almonds is 

 associated with a substance called amygdallne. Diastase is a modification 

 of gluten, obtained from malt, and developed generally during the germina- 

 tion of planrs. It facilitates the conversion of starch into dextrine, and thence 

 into sugar. 



Fixed Oils occur in the cells and intercellular spaces of various parts of 

 the plant. They are known by their greasing paper permanently. The principal 

 are linseed oil, olive oil, and certain solid oils, as palm oil, shea butter, and 

 vegetable tallow. These all contain a large amount of Stearine. 



Vegetable Wax is a peculiar fiitty matter found in the stem and fruit of 

 some plants. On the exterior of fruits it constitutes their bloom, as in the 

 grape and plums. Chlorophylle is allied to wax in character, being soluble in 

 ether and alcohol, and insoluble in water. 



Volatile, or Essential Oils, are procured from such plants as contain 

 them by distillation in Avater, and are known as essences ; they do not grease 

 paper permanently. Usually they are ready formed ; sometimes, however, 

 they are produced by a kind of fermentation. Some essential oils consist 

 of carbon and hydrogen, as oil of turpentine, oil of juniper, oil of lemons, 

 &c. A second set contain oxygen in addition, as oil of cinnamon, otto of 

 roses, oils of peppermint, of caraway, and of cloves. Sulphur enters into 

 the composition of a third set, which are distinguished by a peculiar 

 pungent, and sometimes alliaceous smell, as oils of garlic, of onion, of 

 40 



