addition, and continuing the addition of acetic acid until the liquid above the pre- 

 cipitate becomes clear, or very nearly so. 



2. Provisional method for determination of albumin in coiv's milk. The iiltrate 

 obtained above in separating casein is placed in a water bath and heated to the boil- 

 ing temperature of water for ten or fifteen minutes. The filtered and washed pre- 

 cipitate is then treated by the Kjeldahl method for determining nitrogen. The 

 amount of nitrogen multiplied by 6.25 gives the amount of albumin. 



CHANGES IX METHODS OF C1IKESE ANALYSIS. 



1 'age 37, (a) Preparation of sample. Substitute the following : "When the cheese 

 can be cut, a narrow wedge-shaped segment reaching from the outer edge to the 

 center of the cheese is taken. This is to be cut into strips and passed through a 

 sausage-grinding machine three times, being mixed as completely as possible after 

 each grinding, taking care to avoid evaporation of water. From the mass thus 

 prepared samples are taken for analysis. 



"When the cheese can not be cut, samples are taken by a cheese trier. If only one 

 plug can be obtained, this should be taken perpendicular .to the surface at a point 

 one- third of the distance from the edge to the center of the cheese. The plug should 

 reach either entirely through or only half way through the cheese. When possible, 

 draw three plugs, one from the center, one from a point near the outer edge, and 

 one from a point half way between the other two. For inspection purposes, the 

 rind may be rejected ; but for investigations requiring the absolute amount of fat in 

 the cheese, the rind is included in (he sample. It is preferable to grind the plugs 

 in a sausage machine, but when this is not done, they are cut very fine and carefully 

 mixed.'' 



P:ige 37, (b) Determination of water. Substitute the following for the first two 

 lines: "From 2 to 5 grams of cheese should be placed r.i a weighed platinum or 

 porcelain dish which contains a small quantity of material like freshly ignited 

 asbestus, sand, etc." (Rest unchanged.) 



Page 37, (c) Determination of ether extract. Substitute the following: "Use a test 

 tube containing a perforation in the bottom, or in place of this an extrai tion thimble 

 of fat-free paper. When a test tube is used, place at the bottom some extracted 

 cotton, or glass wool, or asbestus, and, in addition, wrap the lower end outside with 

 filter paper to prevent particles of asbestus or copper sulphate being carried down 

 through the perforation into the extraction flask. Pack the prepared tube as fol- 

 lows: Put first a mixture containing equal parts of anhydrous copper sulphate and 

 pure incinerated sand, filling the tube for about 2 inches. Avoid packing too tightly. 

 Upon this place a little asbestus or other suitable material. Next are added from 2 

 to 5 grams of the sample of cheese which has been weighed for analysis. It is con- 

 venient to place the weighed sample in a little cone of copper foil or of filter paper 

 and slip this into the top of the tube containing the copper sulphate. Phice the tube 

 in a continuous extraction apparatus and exhaust with anhydrous ether. After 

 five hours, the partially extracted cheese is removed and ground with pure sand in a 

 mortar. This partially extracted cheese is brittle, and grinds up about as easily as 

 a dry biscuit. After grinding with the sand, the cheese is replaced in the tube and 

 the extraction continued ten hours longer." 



Page 37, add : "(g) Provisional method for the determination of acidity in cheese. Add 

 water at a temperature of 40 to 10 grams of cheese until the volume equals 105 cc; 

 agitate vigorously and filter. Titrate portions of 25 cc of filtrate, corresponding 

 to 2.5 grams of cheese, with a standardized solution of sodium hydroxid, preferably 

 one-tenth normal. Use phenolphtaleiii as indicator. Express amount of acid as 

 lactic acid." 



CHANGES FROM PROVISIONAL TO OFFICIAL METHODS. 



Page 37, the methods described under (a), (b), (c,, (d), (e), and(f) after modifying 

 as described above. 



