750 APPENDIX. 



plate for a time after the addition of yeast, the sugar is converted into 

 alcohol and carbon dioxide (C 6 H 12 6 = 2C 2 H 5 OH + 2C0 2 ). 



(iv.) Bottcher's test. A little bismuth oxide or subnitrate and an 

 excess of caustic potash are added to the solution in a test-tube, and the 

 mixture is heated; the solution becomes at first gray and then black. 



(v.) Picric acid test. To the solution about a fourth of its bulk of 

 picric acid (saturated solution) and an equal quantity of caustic potash 

 are added, and the solution is boiled; the liquid becomes Qf a very deep 

 coffee-brown. 



(E) Lactose is contained in milk (p. 338). 



Properties. It is less soluble in water than glucose; not sweet, and 

 is gritty to the taste; but it is insoluble in absolute alcohol. Undergoes 

 alcoholic fermentation with extreme difficulty; gives the tests similar to 

 glucose, but less readily. 



(F) Inosite. Inosite is a non-fermentible variety of glucose occur- 

 ring in the heart and voluntary muscles, as well as in beans and other 

 plants. It crystallizes in the form of large, colorless monoclinic tables, 

 which are soluble in water, but insoluble in alcohol or ether. Inosite 

 may be detected by evaporating the solution containing it nearly to dry- 

 ness, and by then adding a small drop of a solution of mercuric nitrate, 

 and afterwards evaporating carefully to dryness, a yellowish-white residue 

 is obtained; on further cautiously heating, the yellow changes to a deep 

 rose-color, which disappears on cooling, but reappears on heating. If 

 the inosite be almost pure, its solution may be evaporated nearly to dry- 

 ness. After the addition of nitric acid, the residue mixed with a little 

 ammonia and calcium chloride, and again evaporated, yields a rose-red 

 coloration. 



(G) Maltose is formed in the conversion of starch into glucose by 

 the saliva and pancreatic fluids. It is also formed by the action of malt 

 upon starch by the ferment diastase, and in the formation of glucose 

 from starch. It is converted into dextrin by dilute sulphuric acid. It 

 is dextro-rotatory; ferments with yeast; reduces copper salts, and crys- 

 tallizes in fine needles. 



MONATOMIC FATTY ACIDS. 



Formic CH 2 2 , acetic C 2 H 4 2 , and propionic C 3 H 6 2 , acids are pres- 

 ent in sweat, but normally in no otner human secretion. They have 

 been found elsewhere in diseased conditions. Butyric acid, C 4 H 8 2 , is 

 found in sweat. Various others of these acids have been obtained from 

 blood, muscular juice, faeces, and urine. 



DIATOMIC FATTY ACIDS. 



Lactic acid, 3 H 6 3 , exists in a free state in muscle plasma, and 

 is increased in quantity by muscular contraction, is never contained in 



