. Market dairying and milk products. Themoment this point is passed is made visible to the eyeby means of the indicator, (phenolphthalein) which iscolorless in the presence of an acid but pink in thepresence of an alkali. One drop of alkali added to milkafter the acid has been neutralized will turn it pink. 83 84 MARKET DAIRYING In the tests used for milk and cream the alkali usedis sodium hydroxide. This is made up of a definitestrength so that the amount of acid can be calculatedfrom the amount of alkali used. Kinds of Tests. There are two tests in general useat the present time: one devised
. Market dairying and milk products. Themoment this point is passed is made visible to the eyeby means of the indicator, (phenolphthalein) which iscolorless in the presence of an acid but pink in thepresence of an alkali. One drop of alkali added to milkafter the acid has been neutralized will turn it pink. 83 84 MARKET DAIRYING In the tests used for milk and cream the alkali usedis sodium hydroxide. This is made up of a definitestrength so that the amount of acid can be calculatedfrom the amount of alkali used. Kinds of Tests. There are two tests in general useat the present time: one devised by Prof. Manns and known as the Manns Test; the other devised by Prof. Farrington and known as Far- ringtons Alkaline Tablet Test. MANNS TEST. The apparatus used in thistest is illustrated in Fig. consists of a 50 burette,a 50 pipette, a small fun-nel, and a glass beaker withstirring rod. The alkali (notshown in the figure) can bebought ready made in gallonbottles and is labeled neutral-izer. This alkali or neutral-. Fig. 32.—Manns acid test appa-ratus. izer is made by dissolvingfour grams of sodium hydroxide in enough water to makeone liter solution. The solution thus formed is called aone-tenth normal solution, each cubic centimeter of whichcontains .004 of a gram of sodium hydroxide which willneutralize .009 of a gram of lactic acid. Making the Test. Measure 50 of cream with thepipette into the beaker, then with the same pipette add50 of water. Now add five or six drops of fill the burette to the zero mark with the neutralizer ACID TESTS 85 and slowly run this from the burette into the cream,shaking the beaker after each addition of alkali. Withthe first few additions of alkali the pinkish color pro-duced quickly disappears. But when the point of neu-trality approaches, the color disappears very slowly andthe neutralizer must be added drop by drop only. Themoment the cream remains pink indicates that the acidhas all been neutralize
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdairyin, bookyear1912
