FORMULA FOR CALCULATIONS. 



Table XX., due to L. J. Harris, serves for the calculation of 

 fat from specific gravity and total solids ; the author has slightly 

 modified the table to render it more convenient. The two 

 factors corresponding to specific gravity and total solids are 

 added to give the fat. 



Tables XXI. and XXII. are tables for calculating solids not 

 fat and fat respectively to the nearest 0-05 per cent., and will be 

 found quite accurate enough for practical laboratory use. 



Density of Constituents. By our definitions (p. 86) 



= Zl and &= 



now, n = , and 



n f 



and from the values given above in the formula mentioned, 

 a and b can be calculated. 



Thus, taking the formula T = 0-2625^ + 1-2 F ; 



0-2625 = J- and 1-2 = - b ~~- a or b - 

 10a a a 



a = 0-381 and b= -0'0762; 

 and / = ___; 



and, therefore, n T616 specific gravity of solids not fat, 

 and /= 0-930 ,, fat. 



From the mode of deducing equation (7) we see that a is the 

 number of grammes that the weight of 100 c.c. of milk is greater 

 than the weight of 100 c.c. of water, when 1 gramme per 100 c.c. 

 of solids not fat is contained therein ; the density being, by 



definition, the weight of 1 c.c., ^ and _^ are respectively the 



difference in specific gravity due to 1 gramme per 100 c.c. of 

 solids not fat and fat. 



It is also apparent that we may calculate from any analysis 

 the amount that 1 gramme of total solids per 100 c.c. has raised 

 the specific gravity, and, from this, the specific gravity of the 

 total solids. 



Thus, using the same symbols as before, 



T =-E*il. and '-TTS 



(t here representing the specific gravity of the^total solids). 



Thus, if a milk has a specific gravity of 1-032 and contains 

 12 per cent, of total solids, 



I2 = m*>m antl *=- 584 



and t = 1-348. 



