422 MILK AND MILK-PREPARATIONS. 



estimation be desired, the amount of sugar both in the whey as well as in the whole 

 milk diluted with water can be titrated directly by means of Fehling's solution 

 (i cu. cm. of which corresponds to 0.0067 gram of milk-sugar) ; or the amount 

 in the whey may be determined by means of the polarization-apparatus. If the 

 estimation is to be made with exactness, the proteid must be removed from the 

 whey; and in addition the fat-globules dissolved out of the whole milk, and the 

 fat extracted. The amount of water, as compared with the amount of milk-cor- 

 puscles (fat) the latter should not be less than 3 per cent, in whole milk, and 

 i$ per cent, in half-skimmed milk is determined by means of the lactoscope (the 

 diaphanometer of Donne, modified by Vogel and Hoppe-Seyler) . This consists of 

 a glass vessel i cm. in diameter with plane parallel walls. A measured quantity of 

 milk is introduced into the vessel and water added from a graduate until the flame 

 of a lighted candle placed about a meter behind the apparatus can be distinctly 

 seen outlined (in a dark room) with the eye placed directly in front of the appara- 

 tus. In such an experiment from 70 to 85 cu. cm. of water are needed for each 

 cubic centimeter of good cow's milk. Feser's galactoscope also is serviceable in 

 the examination of milk, even in the hands of the laity. 



The following substances pass into the milk: fat taken with the food, 

 numerous odorous substances (anise, vermouth, garlic, etc.) ; chloral hydrate, 

 opium, indigo, salicylic acid, iodin, iron, zinc, mercury, lead, bismuth and anti- 

 mony. In cases of osteomalacia the amount of calcium in the milk is increased. 

 Potassium iodid diminishes the secretion of milk. 



Abnormal admixtures include hemoglobin, biliary pigments, mucin, blood- 

 corpuscles, pus, fibrinous clots, tubercle-bacilli and other bacilli. Numerous 

 germs develop in evacuated milk, of which the bacillus cyanogenus, which occurs 

 rarely, gives the milk a sky-blue color. It is the milk-serum that is blue, not 

 the germ. There are also schizomycetes that produce bluish-black and green 

 colors. Red and yellow milk are also observed as a result of similar action by other 

 chromogenic schizomycetes. Red milk is due to the notorious micrococcus 

 prodigiosus, which is itself colorless, and also to the bacterium erythrogenes ; 

 yellow milk, to the bacillus synxanthus. Some of the pigments formed seem to 

 be related to the aniline dyes and others to those belonging to the phenol-group. 

 As the possibility of the entrance also of other pathogenic germs cannot be ex- 

 cluded, the milk should be sterilized by boiling. 



The rennet-like activity of bacteria is widespread, so that they coagulate 

 and peptonize casein and finally cause further decompositions. Thus the butyric- 

 acid bacilli first cause the coagulation of the casein, which they then peptonize 

 and later decompose, with the development of ammonia. Milk becomes viscous 

 from the action of the bacillus lactis viscosus, perhaps in other ways, just as beer 

 and wine may become "long." 



Preparations of Milk. i. Condensed Milk. Eighty grams of cane-sugar are 

 added to each liter of milk, the mixture evaporated to one-fifth its volume and 

 then sealed in tin cans while hot. For the use of nursing infants a teaspoonful 

 is dissolved in a pint of cold water and then boiled. 



2. As a food replacing albumin A. Salkowski recommends the following prep- 

 aration of casein: Casein 20 parts, sodium phosphate 2 parts, water 200 parts, 

 or the soluble ammonia-compound prepared by conducting ammonia over 

 casein (eucasin) ; Rohmann advises acid casein-calcium 3 grams, milk-sugar 4.5 

 grams, di-sodium phosphate 0.375 gram, monopotassium phosphate 0.153 gram, 

 calcium chlorid 0.04 gram, potassium chlorid 0.3 gram, magnesium acetate o.oi 

 gram, water 100 grams. 



3. Koumiss and Kefyr. The Kirghese are accustomed to produce alcoholic 

 fermentation in mare's milk, and the Caucasian mountaineers do the same with 

 cow's milk. As a result of the addition of sour milk, which contains the bacterium 

 lacticum and the bacillus caucasicus, the unfermentable milk-sugar is transformed 

 into fermentable glucose, and by the action of yeast, which is present in an ad- 

 dition of completed koumiss, alcoholic fermentation of the glucose takes place, 

 the mixture being vigorously stirred. Koumiss contains from two to three per 

 cent, of alcohol. The casein, which is precipitated at first and later is partly 

 dissolved again, is transformed into acid-albumin and peptone. The kefyr-fungus 

 (dispora caucasica) also gives rise to a similar preparation, in part containing 

 peptones. In addition to the kefyr-fungus, there is also found the bacterium 

 lacticum and a schizomycete that peptonizes casein, as well as a streptococcus 

 that forms lactic acid and another organism that ferments milk-sugar. Koumiss 

 and kefyr are also prepared at some health-resorts. 



4. Cheese is prepared by coagulating skim-milk (poor cheese), or whole milk 



