of this material with a film of asbestus. On this are placed from 2 to 5 grams 

 of the sample of cheese. The tube is placed in a continuous extraction appara- 

 tus and treated for five hours with anhydrous ether. The cheese is removed and 

 ground to a fine powder with pure sand in a mortar. The mixed cheese and 

 sand are replaced in the extraction tube, the mortar washed free of all matters 

 with ether, the washings being added to the tube, and the extraction is continued 

 for ten hours. 



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

 cheese. Add water, at a temperature of 40, to 10 grams of finely divided 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 phenolphtalein 

 as indicator. Express amount of acid as lactic acid. 



OPTIONAL METHOD OF DETERMINING PHOSPHORIC ACID IN SOILS. 



NOTE. The following method, devised by Mr. Goss, was recommended as an 

 optional method by the association in 1895, but was not ordered printed with the 

 official methods. A synopsis of it is printed here for the convenience of analysts : 



Page 41, after (g), insert the following: 



' ' Ten grams of the air-dried soil, passed through a sieve of one millimeter 

 mesh, are placed in a small Kjeldahl flask marked at 250 cc. From 20 to 30 cc 

 concentrated sulfuric acid and approximately 0.7 gram yellow oxid of mercury 

 are added, the contents of the flask well mixed by shaking, and oxidized over 

 the open flame, as in the determination of nitrogen, for an hour. After cooling, 

 about 100 cc of water, 5 cc of concentrated hydrochloric acid and 2 cc of concen- 

 trated nitric acid are added, and the mixture reboiled to oxidize the iron, cooled, 

 the volume completed to one-fourth of a liter with water, and the contents of 

 the flask filtered through a dry, folded filter paper. One hundred cubic centi- 

 meters of the filtrate are placed in a flask of about 450 cc capacity, strong ammo- 

 nia added until a permanent precipitate is formed, which is dissolved by the 

 addition of about 7 cc of nitric acid, and the mixture boiled until clear. The 

 flask is removed from the flame and cooled at room temperature for exactly two 

 minutes, 75 cc molybdate solution added, and the flask placed in a water bath 

 kept at 80 for 15 minutes, shaking vigorously four or five times meanwhile. 

 After removing from the bath, the flask is allowed to stand for ten minutes until 

 the precipitate has settled, and the supernatant liquid is poured on to the filter 

 paper under pressure, the precipitate being partially brought upon the paper. 

 The flask and precipitate are thoroughly washed with ammonium-nitrate solu- 

 tion, the precipitate either by decantation or in the filter paper. The flask is 

 then placed under the filter, the precipitate is dissolved in ammonia, and the 

 phosphoric acid estimated by the usual processes. Details of the manipulation 

 are given in Bulletin No. 43 of the Division of Chemistry, pp. 58-60. " 



Page 42, omit all of 8 and insert : 



From 7 to 14 grams of the soil are placed in a small Kjeldahl digesting flask, 

 about 250 cc capacity, with 30 cc of strong sulfuric acid, or more, if necessary, 

 and 0.7 gram yellow oxid of mercury, and boiled for an hour. The residue is 

 oxidized with potassium permanganate in the usual way. After cooling, the 

 flask is half filled with water, vigorously shaken, the heavy matters allowed to 

 subside and the supernatant liquid poured into a flask of from 1,000 to 1,200 cc 

 capacity. This operation is repeated until the ammonium sulfate is practically 



