TESTS FOR MILK. 467 



diminished and others increased in amount, according to the time after delivery. 

 The following are increased : Until the 2nd month after delivery, casein and fat ; 

 until the 5th month, the salts (which diminish progressively from this time 

 onwards); from 8-1 Oth months, the sugar. The following are diminished: From 

 10-24th months, casein; from 5-6th and 10-llth months, fat; during 1st month, 

 the sugar ; from the 5th month, the salts. 



[That cow's milk is influenced by the pasture and food is well-known. Turnip 

 as food give a peculiar odour, taste, and flavour to milk, and so do the fragrant 

 grasses. The mental state of the nurse influences the quantity and quality of the 

 milk, while many substances given as medicines reappear in the milk, such as 

 dill, copaiba, conium, aniseed, garlic, potassium iodide, arsenic, mercury, opium, 

 rhubarb, or its active principle, and the cathartic principle of senna. Jaborandi is 

 the nearest approach to a galactagogue, but its action is temporary. Atropin is a 

 true anti-galactagogue. The composition of the milk may be affected by using 

 fatty food, by the use of salts, and above all by the diet (Dolan).] 



[Milk may be a vehicle for communicating disease by direct contamination 

 from the water used for adulteration or cleansing ; by the milk absorbing 

 deleterous gases; by the secretion being altered in diseased animals.] 



The greater the amount of milk that is secreted (woman), the more casein and 

 sugar, and the less butter it contains. The milk of a primipara is less watery. 

 Rich feeding, especially proteids (small amount of vegetable food), increase the 

 amount of milk and the casein, sugar, and fat in it; a large amount of carbo- 

 hydrates (not fats) increases the amount of sugar. 



If other than human milk has to be used, ass's milk most closely resembles 

 human milk. Cow's milk is best when it contains plenty fatty matters it must 

 be diluted with its own volume of water at first, and a little milk-sugar 

 added. The casein of cow's milk differs qualitatively from that of human milk 

 (Biedert); its coagulated flocculi or curd are much coarser than the fine curd of 

 human milk, and they are only f dissolved by the digestive juices, while human milk 

 is completely dissolved. Cow's milk when boiled is less digestible than unboiled 

 (E. Jessen). 



Milk ought not to be kept in zinc vessels owing to the formation of zinc 

 lactate. 



Tests for Milk. The amount of cream is estimated by placing the milk for 

 24 hours in a tall cylindrical glass graduated into a hundred parts; the cream 

 collects on the surface, and ought to form from 10-24 vols. per cent. The 

 specific gravity (fresh cow's milk, 1,029-1,034; when creamed, 1,032-1,040) is 

 estimated with an araeometer or lactometer at 15C. The sugar is estimated by 

 titration with Fehling's solution (p. 298), but in this case 1 cubic centimetre of 

 this solution corresponds to 0'0067 grm. of milk-sugar; or its amount may be 

 estimated with the polariscopic apparatus (vol. ii). The proteids are precipitated 

 and the fats extracted with ether. The fats in fresh milk form about 3 per cent., 

 and in skimmed milk 1^ per cent. The amount of water in relation to the milk- 

 globules is estimated by the lactoscope (the diaphanometer of Donne', modified by 

 Vogel and Hoppe-Seyler), which consists of a glass-vessel with plane parallel sides 

 placed 1 centimetre apart. A measured quantity of milk is taken, and water is 

 added to it from a burette until the outline of a candle flame placed at a distance 

 of 1 metre can be distinctly seen through the diluted milk. This is done in a dark 

 room. For 1 cubic centimetre of good cow's milk, 70-85 centimetres water are 

 required. 



Various substances pass into the milk when they are administered to the mother 

 many odoriferous vegetable bodies, e.g. , anise, vermuth garlic, &c. ; opium, indigo, 

 salicylic acid, iodine, iron, zinc, mercury, lead, bismuth, antimony. In osteo- 

 malacia the amount of lime in the milk is increased (Gusserow). Potassium iodide 



