75 



While, as yet, tlie average figures obtained by the examination of 

 the mixed milk of cows supplying one dairy, has, in all countries, 

 been the same, we find frequently in the milk of single cows great 

 abnormalities, caused by the influence of race, age, constitution, 

 food, time of milking, heat, quantity, season, or whether the cows 

 are on pasture or housed. 



Another desideratum of importance is the method by which 

 analytical results are obtained. They must naturally be exact, and 

 the examinations must be continued for a considerable time, care 

 being taken that physiological and pathological data are carefully 

 noted. This is, unfortunately, frequently omitted. 



To facilitate a control of the market milk, on the part of the 

 authorities, it becomes, therefore, ne'cessary that the limits of com- 

 position of a normal milk, and its physical properties, be defined, 

 in order to avoid reproach and tedious explanation. To fix such 

 limits is, however, not without danger. If we ask too much, we 

 risk that unjust sentences are administered, and, moreover, that 

 the judge will be tempted to be exceedingly lenient in such cases. 

 If we lower the standard too much, we risk that adulterations of 

 minor extent escape punishment. 



Our own standard, which is based upon thousands of examina- 

 tions made by various investigators, and which has been practically 

 proved as good and just, will be given further on. 



It has previously (see page 39) been stated that the adulteration 

 of milk may be practised by the following means ; 



1. Addition of water. 



2. Skimming. 



3. Skimming and addition of water. 



4. Mixing of skimmed milk with whole milk. 



5. Addition of foreign substances, to prevent detection of milk 

 adulterated by any of the processes in 1 to 4. 



Watering and skimming, and the mixing together of such de- 

 teriorated products, or the mixing with whole milk, are the ordi- 

 narily practised means of adulteration. Other substances than 

 water are rarely employed, and then only when it is intended to 

 re-establish a normal appearance of milk which has either been 

 adulterated or which is naturally inferior. The substances used 

 for this purpose have been enumerated on pages 41-43, where 

 also the methods are given by which they may be detected. 



