Ch. XXXVII.] ON MILK. 411 



Mathematical instruments have been invented, as lactometers, for ascer- 

 taining the richness of niillc, in nearly the same manner as tliat employed 

 for trying the strength of spirits ; and an ingenious method has been pub- 

 lished by a Mrs. Lovi fur attaining the same object*. The difference in 

 the quality of milk between particular cows may thus be determined ; but 

 it does not show whether the caseous or the butyraceous matter predomi- 

 nates, and we cannot learn that either mode is much used in our dairies. 



The following observations, drawn from the experiments of Dr. Anderson, 

 may be assumed as a summary of its management : — 



1. " Of the milk that is drawn from any cow at one time, that which 

 comes off at the first is always thinner, and of a worse quality than 

 that which comes afterwards : the richness going on continually increas- 

 ing to the very last drop that can be drawn from the udder at that time." 



2. " If milk be put in a dish and allowed to stand till it throws up 

 cream, that portion of cream which rises first to the surface is richer in 

 quality and greater in quantity than what rises in a second equal por- 

 tion of time ; the cream tluit rises in the second interval ot time is 

 greater in quantity and richer in quality than that which rises in a 

 third equal space of time ; and that of the third than the fourth, and so 

 on: the cream that rises decreasing in quantity, and declining conti- 

 nually in quality, so long as any rises to the surface.'' 



3. " Thick milk always throws up a smaller proportion of the cream 

 it actually contains to the surface than milk which is thinner ; but that 

 cream is of a richer quality. If water be added to that thick milk, it 

 will also afford a considerably greater quantity of cream than it would 

 have done if allowed to remain pure ; but its quality is at the same 

 time greatly debased." 



4. " Milk which is put into a bucket or other proper vessel, and car- 

 ried to any considerable distance, so as to be much agitated and in part 



The analysis of the constituents of skimmed cows' milk is stated by chemists to be — 



Water 



Cheese, with a trace of butter 



Suji;ar of milk 



Muriat of potash . . 



Phos[)hate of potash . 



Lactic acid, with acetate of potash 



Earthy phosphate 



* She places beads into the milk as drawn from the cow, and put into a g-lass vessel 

 at the heat of 60 degrees. The same operation is then repeated on the skimmed milk, 

 after the cream has been removed, and the difference in tlie specific gravity of the 

 milk in these separate states shows its quality : the full milk, coutainiofj: the cream, 

 bein^ lighter than that v/hich has been skimmed. Tlie beads are numbered, and are 

 singly thrown in until one sinks to the bottom and another swims ; the intervening 

 number between them expressing the specific gravity : thus, as the cream is the lightest 

 ingredient, the diversity of the weigbt of the milk affords a sure indication of the rela- 

 tive quantities of oily matter or butter. 



The proportions of cheesy matter can only be ascertained by curdling the skimmed 

 milk, and trying the whey, in the same manner, alDiig vsith the skimmed milk; the 

 whey being the lighter of the two: thus, if the skimmed milk stand at 36, and the 

 whey in once instance at 32, and in another at 34, it may be inferred that the first will 

 be more productive thau the latter. 



It has been found from experiment that the beads applicable to some different kinds 

 of milk, show, according to their several numbers, the following results, namely: — Cows, 

 from 24 to 34 ; but when fed on icrass, before being creamed, 32 ; and after the cream was 

 taken olfj 40 ; — Ewes, before being creamed, 36 ; after the cream was taken oti', 48 ;— 

 Goats, 34; Asses, 34 ; Mares, 36. The two latter, however, though considered higlily 

 nutritive, afford scarcely any cream. 



