BY H. S. HALCKO WAKDLAW. 823 



cerned solely with the butter-producing quality of the animal. The 

 series of more complete analyses are, in general, too short to allow 

 any useful conclusions to be drawn from them. Among the few 

 extensive series of analyses may be mentioned those of Collins 

 (1904), whose object was to calculate the probabilities of devia- 

 tions of different magnitude from the legal standard; and of 

 Fresenius(1909). This work, too, however, was conhned chietiy to 

 an examination of the fat-content. Lythgoe {luc. cit.) carried out 

 a very extensive investigation of a similar character, in whicli 

 other constituents besides fat were determined. 



The statements of the different investigator.s, as to the relative 

 variabilities of the constituent of milk, are not very concordant. 

 Nearly all agree in one conclusion, however, and that is that the 

 most variable constituent of milk is the fat. The majority of 

 investigators also find milk-sugar to be the least variable of the 

 constituents, but, on this point, the agreement is not so complete. 



ticope of Present Work. 



The object of the work recorded in this paper is to present a 

 series of complete analyses of samples of the evening-milk of 

 hidividual cows. The cows examined were not chosen for the pos- 

 session of any special qualities. They were, however, members of 

 herds which were maintained under the most favourable conditions, 

 and were not kept for profit. All the cows examined were supply- 

 ing milk which was being used for human consumiDtion, and all 

 were milked under the same conditions, as regards time of milking 

 and period since last milking. The cows had not been subjected 

 to any change of diet for several weeks, at least, before the collec- 

 tion of tlie samples. The collection of samples extended over three 

 seasons of the year. Over one hundred samples of milk were 

 examined, and determinations were made of: (1) the yield of 

 milk; (2) density; (3) freezing-point; (4) electrical conductivity; 

 (5) total solid matter; (6) fat; (7) sugar; and (8) ash. From 

 these results, the percentages of protein and extractives, and of 

 solids not fat, and the total quantities of fat yielded were cal- 

 culated. 



