BOS TAURUS. 



preaching to chestnut. Those of a yellow color are reported 

 to be subject to the steal (diarrhoea). The Plate, No. 3, is 

 taken from Low's splendid work upon British Animals. 



CHEMICAL AND MEDICAL PROPERTIES AND USES. 



MILK, or to be more precise in our description, Cow's milk 

 is an opaque, white, emulsive liquid, with a bland, sweetish 

 taste, and a faint peculiar odor. The constituents of milk 

 are butter, which varies from 2 to 6. per cent. ; casein or 

 cheese, usually 4 to 5, but sometimes varying from 3 to 15 

 per cent, (the last excessive quantity yielded only by the 

 first milk after calving) ; milk sugar, 4 to 6 per cent. ; salts 

 or saline matter, 0.2 to 0.6 per cent. ; and water, 80 to 89 per 

 cent. Milk in general contains from 10 to 12 per cent, of 

 solid matter on being evaporated to dryness by a steam heat. 

 The mean specific gravity of cow's milk is 1,030 grains, but 

 it is less if the milk be rich in cream. This latter property, 

 therefore, is subject to considerable variation. Milk owes its 

 whiteness and opacity to an emulsion composed of the case- 

 ous matter and butter, with sugar of milk, extractive matter, 

 salts, and free lactic acid. 



The curd of milk, or caseous matter, partakes in many of its 

 chemical properties of the nature of albumen ; in others it re- 

 sembles vegetable gluten, more especially in the fermentation 

 which it undergoes when kept in a moist state. Sugar of 

 milk is obtained by evaporating whey. When purified it has 

 a sweet taste, and requires 7 of cold and 4 of boiling water 

 for solution, and is insoluble in alcohol ; when digested with 

 nitric acid, it is partially converted into mucous or saccholac- 

 tic acid, and not, like common sugar, into oxalic acid. This, 

 therefore, though an animal product, closely resembles the 

 vegetable proximate principles ; and milk may hence be con- 

 sidered as partaking of the nature of vegetable as well as ani- 

 mal food. 



When milk, contained in wire-corked bottles, is heated to 

 the boiling point in a water-bath, the oxygen of the included 

 small portion of air under the cork seems to be carbonated, 

 and the milk will afterwards keep fresh, it is said, for a year 

 or two ; as green gooseberries and peas do by the same treat- 

 ment. 



Milk is an exceedingly valuable substance in irritation of 



7 



