an acicl^ as explained on page 2lK), ai.*t i»t luHnr- T«\; lairiy constant proportion*.. If ai4 tx*v-x » f Iu^ dissolve the casein, the unet mhinod Ht>r tL. The average milk being 1.032, 10.5 cc may be .iieaM accuracy for most work. * n train I \vlll ife gravity 'vit> -n^i of Casein: Hart's Method.—Place 10.3 f 200-cc Erlenmeyer fl.ask containing 75 cc of distilled water freed from carbon dioxide by boiling, then cooled to 20". 10-per cent acetic acid, warm to about 40° and filter off the e. 10-cra filter. Wash the paper and precipitate thorough! 250 cc of cold water. Return the paper and contents to f flask, add. 75 cc of carbon dioxide-free water and a drop of p] To this add 10 cc of tenth-normal potassium hydroxide. St and sbiaJke vigorously. When solution of the protein is com; the disappearance of the red color, using tenth-normal acid, to run a blank as this will usually require 0.2 cc or more of tf: potassium hydroxide. The number of cubic centimeters of I titratloxij thus corrected, will express the per cent of .—Albumin Is soluble In the milk serum and Is lable by heating to 100°. It Is necessary, however, first "to neutralize part of the acetic acid. If this was to precipitate casein. D etemainatioii of Albumin.—Xeutralize the filtrate from the casein deter- mination (acetic acid method) with tenth-normal sodium hydroxido or potaussium hydroxide, using phenolphthalein, or use the filtrate from the alum precipitation of casein without neutralization. Add 0.3 cc of 1O—pier cent acetic acid and heat in a boiling-water bath until the5 precipit.*xf:-e becomes settled. Filter, wash with cold water and determine the nitrogen and albumin as in the casein determination, using the same factor. A comparison of the results obtained by various methods for determining milk proteins has been made by Spitzer,1 \vlio concluided that where speed and convenience are important tfa.e forra.a.1 titration is to be preferred. Ind. Acad. Sri., p. 173 (1915).