Analysis of Sour Milk. 



397 



course both the physical and chemical changes, which take 

 place in milk on keeping, are apparently very profound ; 

 the lactose is more or less converted into lactic acid and the 

 casein is precipitated. Sour and curdled milk is apparently 

 very different from fresh milk. But the real point is that these 

 changes do not materially affect the accuracy with which the 

 total solid matter, or the fats and non-fats, present in the fresh 

 milk, may be ascertained, and hence do not materially affect the 

 certainty with which the charge of watering or abstraction of 

 fat may be substantiated or disproved. Lactose, by hydrolysis, 

 gives its own weight of lactic acid, and the fat itself is practically 

 unaffected by the souring. 



" The sole difficulty arises from the circumstance that con- 

 currently with the transformation of the lactose into lactic acid 

 a certain very small quantity of the sugar is converted into 

 alcohol and into more or less acetic acid. The amount so 

 formed is very variable, and may depend upon accidental 

 circumstances such as the absence or presence of particular 

 spores or ferments. The samples upon which our experiments 

 were made were market milks, just as liable to the influence of 

 accidental germs or stray ferments as those taken by an 

 Inspector. The difficulty after all is only a minor one as the 

 extent of the change is very small as a rule. Although its 

 degree cannot be followed with absolute precision, it must be 

 obvious to anyone who will look at the published results, or 

 better still repeat the work for himself, that a very close 

 approximation to accuracy is obtained. 



" I am of opinion that processes involving sterilisation, 

 pasteurisation, or the use of antiseptics are not called for, and 

 might introduce far more elements of uncertainty in the case 

 than they are calculated to remove. 



" The circumstances do not call for any departure from 

 established usage. If an Inspector intelligently follows the 

 procedure which has been laid down by the Board of Agri- 

 culture, there is really no difficulty, in the great majority of 

 cases, in affording the Court the information required. In the 

 very few and wholly exceptional cases in which we are unable 

 to give the information, owing to the condition of the sample, 

 we say so. In the larger number of these exceptional cases the 



