GLUCOSE. 13 



contain grape-sugar after a diet rich in carbohydrates. 

 Whether it may normally occur in very small amounts in 

 the urine is a question which is often discussed, but upon 

 which there is no general agreement. 



Glucose is made commercially by boiling starch with 

 a dilute acid. It can be produced from any of the poly- 

 saccharids or disaccharids in the same manner. They unite 

 with one or more molecules of water, forming glucose: 



(C 6 H 10 5 ) x +x H 2 = x C 6 H 12 6 . 

 C 12 H 2 Ai + H 2 2C 6 H 12 6 . 



Pure glucose can be made from pure cane-sugar by 

 dissolving it in alcohol and adding hydrochloric acid. The 

 glucose crystallizes out on standing. 



Glucose is a crystalline substance, but crystallizes with 

 difficulty from water. It can better be crystallized from 

 methyl alcohol or ethyl alcohol. Its taste is sweet, but less 

 so than that of cane-sugar. It is easily soluble in water or 

 hot alcohol. With yeast, glucose ferments best at about 

 25 C., forming alcohol and carbon dioxid: 



C 6 H 12 6 = 2C 2 H 5 OH + 2C0 2 . 



In the presence of milk or cheese it ferments to lactic 

 acid. Calcium carbonate or oxid of zinc must be added to 

 keep the solution neutral if it is desired that the action go 

 on for a long time, as the presence of the acid kills the 

 ferment: 



C 6 H 12 6 = 2C 3 H 6 3 . 



By the action of another ferment the lactic acid is 

 changed into butjrric acid: 



2C 3 H 6 3 = C 4 H 8 2 + 2C0 2 + 4H. 



