^4 ANALYSIS OF JIILK. 



The following formula expresses the percentage of anhydrous 

 milk-sugar in the milk Avhen a tube of 198-4 mm. is used : — 



1 -042 "^ ^iOO ■ - rf -" " "^^ 



»i^ = percentage of anhydrous milk-sugar by weiglit, 

 /' = reading, 



F = percentage of fat by weight, 

 d = specific gravity of milk. 



For the expression -—-- it is usually exact euouuh to employ 



the expression F X I'll. 



As an example, let us suppose that, using a 198 '4 mm. tube 



r = 5V 

 F = 4-l 

 d = 1-032 



5'5 1 



'"' = Tm^o ^ ''■'5545 X -]-™y X 0-95 = 4 58 per cent. 



Vieth states that when cream is analysed by this method, it 

 is necessary to dilute with an ec[ual bulk of water, the results 

 being, of course, doubled. 



Richm.ond - Boseley Method. — The author,, in conjunction 

 with Boseley, has shown that the calculation necessary in Vieth's 

 method can be eliminated Isy adding to 100 c.c. of milk 



(a) A quantity of water in c.c. ecpial to I'j dugiee of specific gravity. 



(6) „ ,, „ ,, thefatxl-ll. 



((•) ,, ,, ,, to reduce scale readings to percentages 



of milk-sugar, 

 (d) 3 CO. of acid mercuric nitrate. 



Tiie percentage of milk-sugar can be read oti' directly in scale 

 feadings. 



The values of c are : — For polariscopes reading angular 

 degrees — 



With 198-4 mm. tube, 10-0 c.c. 

 „ 200 „ 10-85 „ 



„ 500 ,, 10-85 „ (divide readings by 2-5). 



For the Laurent sugar scale (100°= 21-67 angular degrees) — 



With 200 mm. tube, 2-33 c.c. (divide readings by 5). 

 „ 400 „ 2-33 „ ( „ „ 10). 



.. 500 ,, 2-33 „ ( „ „ 12-5) 



For the Ventzke scale (100°= 34-64 angular degrees) — 



With -2011 mm. tube, Hll.5 c.c. (divide readings by 3). 

 >. 400 „ ■ 6-(}5 ,, ( „ „ 6). 



.. 500 „ fi-65 „ ( „ „ 7-5). 



The author has recently shown that mercuric nitrate does not 

 precipitate the whole of the proteins, and that a small further 



