SPECIFIC VOLUME. 7] 



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, ^rui and ^ttk 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 



i = y, X ,-^-, and t = : 



D IOk 1 - as 



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



Thus, if a milk has a specific gravity of r()32 and contains 

 12 per cent, of total solids, 



and t = 1 -348. 



It is occasionally useful to cakulato the specific j,'ravity of 

 the total solids of a milk, as the total solids of skimmed milk 

 have a considerably higher specific gravity than thosr of whole 

 milk. 



Specific Volume — By om- definition of specific gravity, 



we write 8 = . . ; we may also write, ^ = tt? • *''"' ^'^ words, 



, expresses the volunu' of 1 gramme ; this is called specific 



^ G 



volume. The expression ^r is, therefore, a mode of indicating 



specific volumes ; as G (degrees of specific gravity) is 1.000 times 



the specific gravity minus 1,000. so „ (degrees of specific volume) 



is 1,000 minus 1,000 times the specific volume. 



In Table VII. the values of degrees of specific volume for 

 each half degree of specific giavity from "20 to 36 are given. 



It is seen from the formulae above, that 1 per cent, by weight 

 iowi'is the specific volume to the same extent as 1 gramme per 

 loo c.c. raises the specific gravity — i.e., specific volume, not 

 specific giavitv, varies directly as percentage by weight. 



