14 CONTENTS 



PAGE 



Determination of ash, 179 Determine tion of proteins, 181 Volu- 

 metric methods of estimating casein, 185 Determination of milk- 

 sugar, 191 Determination of acidity, 196 Milk sediment test, 200 

 Test for viscosity, 207 Rennet tests, 207 Alcohol test, 208 

 Albumin test for heated milk, 210 Tests to distinguish human and 

 cow's milk, 210 Fermentation tests, 210 Bibliography, 211. 



ADULTERATIONS OF MILK 213 



Kinds of adulterations, 213 Detection of watered and skimmed 

 milk, 214 The lactoscope, 2J6 The immersion refractometer, 217 

 Test for nitrates, 219 Detection of thickening agents, 219 Addi- 

 tion of foreign fat, 220 Coloring-matter in milk, 221 Addition of 

 preservatives, 223 Detection of formaldehyd, 225 Detection of 

 borax and boric acid, 227 Detection of benzoic acid, 228 Detection 

 of salicylic acid, 229 Detection of sodium carbonate and bicarbonate, 

 229 Bibliography, 229. 



ENZYMS IN MILK 230 



Nature of enzyms and source of milk enzyms, 230 Proteolytic en- 

 zyms, 231 Carbohydrate-splitting enzyms, 233 Qxydases and 

 reductases, 234 Tests for the presence of enzyms, 237 Bibliography, 

 239. 



THE TRANSMISSION OF TOXINS AND ANTIBODIES THROUGH MILK 240 



Transmission of toxins, 240-^Transmission of antitoxins, 241 

 Transmission of other antibodies and hypersensitiveness, 243 The 

 precipitin test, 244 The complement-fixation test, 245 Tests for 

 mastitis and colostrum milk, 246 Test for rennet inhibition, 248 

 Bibliography, 248. 



THE GERMICIDAL ACTION OF FRESH Cow's MILK 249 



Early observations, 249 Late work, 250 Present state of knowl- 

 edge, 256 Bibliography, 256. 



MICRO-ORGANISMS IN MILK 258 



Sources of micro-organisms, 258 Distribution of micro-organisms 

 in milk, 258 Distribution of micro-organisms in cream, 259 Bac- 

 teria in market milk, 261 Souring of milk, 264 Contamination of 

 milk in the udder, 267 Source of bacteria in the udder, 269 Num- 

 ber of bacteria in the udder, 269 Distribution of bacteria in the 

 udder, 270 Growth of bacteria in the udder, 273 Kinds of bacteria 

 in the udder, 274 Contamination during milking operations, 278 

 Dust from the stable air, 286 Influence of fodder on stable air, 290 

 Bacteria in stable air, 293 Contamination from the hands and 

 clothes of milkers, 295 Wet and dry milking, 296 Milking pails, 

 297 Milking machines, 305 Contamination from utensils, 314 

 Contamination of creamery and cheese factory by-products, 323 

 .Contamination during transportation, 327 Growth of bacteria at low 

 temperature, 331 Contamination in the hands of dealers and con- 

 sumers, 332 Aeration of milk, 335 Milk bottles, 335 Bibliography, 

 337. 



THE KINDS OF MICRO-ORGANISMS IN MILK 340 



Grouping of bacteria found in milk, 342 Lactic acid bacteria, 343 

 Classification of lactic ack bacteria, 344^Distribution of lactic acid 

 bacteria, 350 Products oi lactic acid bacteria, 352 The kinds of 

 lactic acid produced by lact'c acid bacteria, 357 The kinds of curd 

 formed by lactic acid bacteria, 360 Lactobacilli, 365 Acids pro- 



