THE ADULTERATION OF MILK. 533 



212° F., in order to remove all traces of the fluid. The loss of weight 

 experienced as the result of this treatment equals the amount of fat. 



The amount of mineral salts is determined by igniting the residue 

 until it is perfectly white. The heat must be very gradually increased 

 in order to avoid loss from sputtering. The ash is then directly weighed, 

 and its percentage value obtained as in the case of the total solids, that 

 is, by the ratio of its weight to the amount of milk originally taken. 

 The water is readily found by subtracting the per cent of total solids 

 from 100. 



The operations described above are all very easily made, and require 

 comparatively but a short time. They presuppose, of course, the em- 

 ployment of a certain amount of apparatus, but if one can depend upon 

 the courtesy of some chemical or pharmaceutical friend for the use of 

 an analytical balance, all of the other requirements can be met at no 

 very great expense. An analysis such as has been outlined, will show 

 conclusively the quality of any suspected sample of milk, for the milk 

 Avill deviate from the normal condition just in proportion as its constitu- 

 ents differ from those of the standard given. If, for instance, it is 

 found that the specific gravity and percentage of total solids are both 

 low, the addition of water is plainly indicated. By calculating the 

 amount of whole milk corresponding to the total solids found, it is 

 possible to state just how much water has been added. When it is 

 found that the specific gravity is as it should be, and the total solids 

 are between 12 and 12*5 per cent, it is seldom worth while to continue 

 the analysis further than a determination of the mineral salts, for it 

 would scarcely be possible for these three quantities to be what they 

 should be unless the milk were quite normal. Thus, in a sample of 

 milk recently analyzed by the writer, the specific gravity was found 

 to be 1'033, the total solids 12"077 per cent, the mineral salts 0*598 

 per cent, and the water 8T'923 per cent. Though the solid constitu- 

 ents were somewhat low, the discrepancy was too slight to fancy for 

 a moment that the milk had been tampered with in any way. 



Occasionally chalk or lime-water is added to give body to a diluted 

 milk. Its presence will be readily detected by the increased amount 

 of ash, which may be examined by the well known qualitative meth- 

 ods. During the warmer months, the difficulties of keeping milk fresh 

 not infrequently lead to the addition of bicarbonate of soda or borax, 

 but as a preservative the latter salt is an absolute failure. It simply 

 keeps the curd from precipitating, but does not prevent the decompo- 

 sition of the milk. After standing some time such a milk will be found 

 to emit a very putrid, disagreeable odor. 



Though the addition of these adulterants is far from commendable 

 on the part of the milkman, the reflection is not without comfort that 

 they exercise for the most part no injurious influence on the animal 

 economy — a reflection, by the way, which can not be indulged in about 

 the majority of food adulterants. 



