AZOTISED VEGETABLE PRODUCTS. 145 



molecular arrangement. The unazotised products which have been 

 noticed, supply carbon for the respiration of man and animals, and 

 probably assist in the formation of fat. It is impossible to notice all 

 the compounds of carbon, oxygen, and hydrogen, found in plants. 

 Some of these exist in small quantity in particular plants. For 

 example, Salicine, a bitter neutral crystalline substance, is procured 

 from the bark of Salix alba, Helix, purpurea, viminalis, pentandra, 

 &c.; and Phloridzine, an analogous substance, occurs in the bark of 

 the roots of the apple, pear, and plum. 



310. Azotised Products. There are certain azotised products which 

 exist in greater or less quantity in plants, and which are particularly 

 abundant in grains and seeds. The nutritive matter of wheat consists 

 of starch or unazotised matter, separable by washing, and of azotised 

 matter or gluten. Gluten is composed of certain proteine compounds 

 (Fibrine, Caseine, Albumen, Emulsine), containing carbon, oxygen, 

 hydrogen, and nitrogen, with some phosphorus and sulphur. Vegetable 

 fibrine is the essential part of the gluten of wheat, and of the cereal 

 grams. It may be procured by treating with ether the glutinous mass left 

 after kneading wheat flour in linen bags under water. Vegetable caseine 

 or legumine is an essential part of the seeds of Leguminous plants, and 

 also of oily seeds. It may be procured in solution from kidney beans 

 and peas, by bruising them in a mortar with cold water, and straining. 

 Vegetable albumen occurs in a soluble form associated with caseine. It 

 forms a small proportion of cereal grains. Wheat is said to contain 

 to 1^ per cent.; Eye, 2 to 3f per cent.; Barley, J 5 to per cent.; 

 jind Oats, ^ to J per cent. It is distinguished by its coagulation at 

 a temperature of 140 to 160, and by not being precipitated by 

 acetic acid. These three compounds dissolve in a solution of caustic 

 potash ; and if to the solution acetic acid is added, the same precipitate 

 is obtained whichever of the three is employed. This precipitate is 

 called Proteine (WQUTWU, I have the first place). Its formula is C 48 

 H 36 N 6 O u . Fibrine is proteine -j- S. + Ph. Albumen is proteine + 

 S 2 -J- Ph. Caseine is proteine + S. Emulsine, or synaptase, is a nitro- 

 genous compound found in certain oily seeds, as in almonds. It 

 exists in the milky emulsion which these seeds form in water, and it is 

 coagulated by acetic acid, and by heat. In bitter almonds, it is 

 associated with a substance called amygdaline, on which it acts in a 

 peculiar manner, producing hydrocyanic acid. Diastase is an azotised 

 substance procured from malt, and developed during the germination 

 of plants. It is probably fibrine in an altered state, and it has the power 

 of promoting the conversion of starch into sugar. 



311. The azotised products of plants have a similar composition 

 with blood and muscular fibre, and hence their value in the food of 

 man and animals. The following table gives a general view of the 



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