XVIII. METHODS FOR THE ANALYSIS OF DAIRY PRODUCTS. 



MILK. 



1. Total Solids. Official, 

 (a) METHOD I. 



Heat from 3 to 5 grams of milk at the temperature of boiling water until 

 ii ; -eases to lose weight, using a tared flat dish of not less than 5 cc diameter. 

 It' desired from 15 to 20 grams of pure dry sand may be previously placed in 

 the dish. Cool in a desiccator and weigh rapidly to avoid absorption of hydro- 

 .scopic moisture. 



(b) METHOD II. (BADPOCK ASBESTOS METHOD.) 



Provide a hollow cylinder of perforated sheet metal, GO mm long and 20 nun 

 in diameter, closed 5 mm from one end by a disk of the same material. The 

 perforations should be about 0.7 mm in diameter and about 0.7 mm apart. Fill 

 li osely with from 1.5 to 2.5 grains of freshly ignited, woolly asbestos, free from 

 line and brittle material, cool in a desiccator, and weigh. Introduce a weighed 

 quantity of milk (between 3 and 5 grams) and dry at the temperature of boiling 

 water to constant weight. 



2. Ash. Official. 



Weigh about 20 grams of milk in a weighed dish, add 6 cc of nitric acid, 

 evaporate to dryness, and ignite at a temperature just below redness until hte 

 ash is free from carbon. 



3. Total Nitrogen. Official. 



Place about 5 grains of milk in a Kjeldahl digestion flask and proceed, witli- 

 vaporation, as described under " I. Fertilizer Methods" for the detenu ina- 

 of nitrogen, page 5. Multiply the percentage of nitrogen by 6.38 to obtain 

 litrogen compounds. 



4. Casein and Albumin in Cow's Milk, 

 (a) CASEIN. OFFICIAL. 



The determination should be made when the milk is fresh, or nearly 

 WhiMi it is not practicable to make this determination within twenty-four hours, 

 add 1 part of formaldehyde to 2,500 parts of milk, and keep in a cool plan-. 

 Place about 10 grams of milk in a beaker with about 00 cc of water at 40 to 

 C., and add at once 1.5 cc of a 10 per cent acetic acid solution. Stir with a 



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