90 



be used with two grams of zinc sulphide. The use of oue flask for both 

 digestion and distillation, thus doing away with the necessity of trans- 

 ferring the solution from the digestion to the distillation flask, is 

 strongly recommended. 



Phosphoric acid. — The methods recommended for preparation of sam- 

 ple and determination of moisture remain the same as last year. In 

 estimating the water-solnble phosphoric acid the residue is to be washed 

 until the filtrate measures 250 c. c. In filtering oft' the portion soluble 

 ill citrate of ammonia, washing with water at 65° 0. is recommended. 

 In making up the solution for total phosphoric acid, with all fertilizers 

 containing cotton-seed meal, the substance is to be first evax)orated 

 with magnesium nitrate and ignited. In the preparation of the neutral 

 citrate of ammonia solution, a ''saturated alcoholic solution of coral- 

 line" should be used as an indicator. The present method of determin- 

 ing reverted or citrate-soluble phosphoric acid was discussed at some 

 length, and the reporter on phosphoric acid for the coming year was 

 requested to make a careful study of the preparation of the citrate 

 of ammonia solntion and the time of digestion. 



Potash. — The changes adopted were but slight, the methods of last 

 year having proved satisfactory and reliable. Attention was called 

 to the necessity of first charring substances containing organic matter, 

 as cottonseed meal, etc., before making up the solntion, this i)recau- 

 tion to be observed in both the LindoGladding method and the alter- 

 nate method. In the former method, the direction to " cool the solu- 

 tion" before adding ammonium oxalate and ammonia, is omitted. 

 The wording of the alternate method is changed to avoid ambiguity, 

 but the general import remains unaltered. 



Cattle foods : Preparation of the sample. — The substance is to be ground 

 until all of it will pass through a sieve of plate metal witli circular holes 

 1 millimeter in diameter. Moisture. — The substance is to be dried dur- 

 ing four hours, instead of " to constant weight." Ash. — The method 

 remains the same as last year, with the exception that the determina- 

 tion of carbon dioxide in the charred mass is omitted, and the material 

 heated at low redness to a white ash. JPflt— The ether extraction is to 

 be carried on during sixteen hours, instead of "until extraction is found 

 by test to be complete." Protein. — In est imating crude protein the nitro- 

 gen is to be determined by the Kjeldahl method, as directed for nitrogen 

 in fertilizers, and the result multiplied by 6.25. Crude fber. — In the 

 method for crude fiber the use of tlie air blast in boiling with acid and 

 alkali is made optional; the directions as to filtering are dropped, and 

 the washing with alcohol and ether is omitted. 



Dairy products. — Butter. — The sample of about 500 grams, which may 

 be taken with a butter tester, is to be perfectly melted in a closed ves- 

 sel at as low a heat as possible, and shaken violently to mix ; a portion 

 oftliis is poured into the vessel from which it is to bo weighed out for 

 analysis, and kept in motion until cool. Specif e gravity. — This may be 



