MILK SCALE. 



69 



the same results, but is more scientifically cor- 

 rect, and which does not require the application 

 of approximations. This is 



2(i2j^+ M7F. 



As the previous formulae were deduced from 

 analyses to which objection could be taken, the 

 author has deduced a new formula from the 

 results of analyses made as exactly as possible. 



T 



(l-2(i25 + 1-2 V. 



This has l)i'cii found to be expressed by the 

 ^,' i ^ F + 0-14 within 



spec 



ific I'ravitv li 



si,mpler formula T 



very small limits if the 

 betwci'ii l-()2() and 1-036. 



The formula T = -r + -^ F also approximates 



closely to that of Hehner and the author. 



Other formulas have been devised by J. ('. 

 Brown, Babcock, Leonard, and others. 



Of the above formulic, that of Flcischniann 

 agrees best with the results when Soxhlet's 

 method of fal estimation is used : tiiatof Hehner 

 and the author when the Soeiety of I'ublic 

 Analysts' methods are employed ; while if the 

 methods mentioned later as most exaet in the 

 author's opinion be emjiloyed, the author's 

 formula i^ives the most satisfactory results. 



The fat calculated from the specific gravity 

 and total solids almost invariably agrees within 

 0'2 per cent, with the determination made by 

 the appropriate method. 



Milk Scale. — In order to save calculation the 

 author has de\-ised a slide rule, known as the 

 " milk scale " (Fii;. 4). from which the percentage 

 of fat can be read off directly from the specific 

 gravity and percentage of total solids. On one 

 side a scale is placed indicating total solids, 1 

 per cent, of total solids being represented by 1 

 inch : on the other side the fat is shown by a 

 scale of \-l {1\ inches) to 1 per cent. ; the slide 

 carries the specific gravity scale. 1 being ei|ual 

 to 0"1^> (J) inch. The line indicating the specific 



J^ 



Fig. i. 

 Jlilk Scale 



