66 SCIENCE AND PRACTICE OF DAIRYING. 



According to the nature of the conditions under which, as has just 

 been described, milk is to be regarded as adulterated, every kind of 

 preservative used for milk must also be regarded as an adulterant. 

 Indeed, it may be concluded that there is something of a deceitful 

 intention in the secret use of such agents, since the buyer is under 

 the impression that the sweet condition of the milk is the result of 

 its fresh state, or of the careful and cleanly treatment to which 

 it has been subjected before sale, and is thus grossly deceived. 



In former times, before much experience had been obtained in the 

 supervision of the milk trade, it was customary to draw up a formal list of 

 adulterants said to be found in milk, as well as methods for detecting all 

 possible and impossible adulterants, which were systematically arranged in 

 a tabular manner. Thus, in addition to the adulterants above referred 

 to, adulteration with albumin, white of egg, caramel, artificial emulsions, 

 meal, gum, dextrin, glue, bird-lime, soapy water, calcium and magnesium 

 carbonates, the pulverized brains of calves, sheep, and horses, and many 

 other things were spoken of. The large experience which has been gained 

 in the course of the last twenty years has shown that in Germany, at least, 

 hardly one of the above-mentioned and highly improbable adulterants 

 have been used. Further reference need not be made to them, since they 

 have no general interest, and if they ever were practised would, by means 

 of the present methods of chemical analysis, be very easily detected. 



31. Milk Testing. In consequence of the adulterations of milk 

 described in 30, it has to be determined, in testing milk, whether 

 the average chemical composition of the milk has been altered, 

 by external influences, after it has left the udder, so as to differ 

 from that of milk furnished by continuous and perfect milking, 

 and, in the case of any change having occurred, to discover the 

 nature of the influence that has produced the change. In the first 

 place, it is necessary to obtain as accurate a determination as possible 

 of the properties of the suspected milk ; in the second place, an exact 

 knowledge of the usual average chemical composition and the usual 

 nature of the milk obtained in that district; and thirdly, it is 

 necessary to have an ample knowledge, gained by experience, of the 

 limits of variation in the composition and specific gravity of milk. 



Chemical analysis of all the constituents, and the determination 

 of the specific gravity, afford the most reliable evidence of the quality 

 of the milk. As, however, in earlier times it was only in very 

 exceptional cases possible to conduct such an investigation, it was 



