SPECIFIC GRA VITY OF MILK 



179 



Now, weight of water in bottle at 1 5 ° C. = (^ — ^) grams. 

 „ milk „ „ =(^—^) grams. 



Hence specific gravity of milk = -7 



Jf the pyknometer (Fig. 22) be employed, the 

 method adopted is identical in every way, excepting 

 that the liquid is sucked up into the vessel, and the 

 level in the right-hand limb adjusted to the mark b by 

 carefully applying a piece of filter paper to the point a. 



(^:^ 



«:::0 



Fig. 22.— Pyknometer. 



177. Determination of Specific Gravity by 



WestphaVs Balance. 



Westphal's balance (Fig. 23) is an apparatus for obtaining the 

 densities of liquids by determining the weight required to sink a 

 standard float below the surfaces of the liquids. The weights 

 employed are in the form of wire riders, which can be placed at 

 different positions on the same beam as that to which the float is 

 attached. The density is then read off directly from the gradua- 

 tions on the beam, and in most instruments can be obtained to 

 four places of decimals. 



