182 EXPERIMENT STATION RECORD. 



KJeldalil metliod 13.83 per cent. On pure sodiiuii nitrate the average 

 by tlie /jiic-iroii metliod was I.j.05 per cent, by tbe modified Kjeldalil 

 method 15.S8 per cent. 



In a paper on "The standardization of normal acid and alkali solu- 

 tions," by H. K. Miller, the results of a comi)arison of the leading proc- 

 esses were reported. 



aS'o<7,s- and ash. — The report on this subject was presented by A. M. 

 Peter. The results of comparative tests by different analysts showed 

 that the great irregularities did not permit of computing averages or 

 of drawing very definite conclusions. The recommendations of the 

 reporter, which were adopted by the convention, ijrovided for subjecting 

 to analysis only that portion of the soil which passes a sieve having 

 circular holes i mm. in diameter; for separating the soluble silica before 

 ignition to determine the carbon; for the elimination of the error in 

 carbon determination due to the water in hydrated silica, and for diges- 

 tion for 10 liours under atmospheric pressure in a flask provided with 

 a condenser to prevent evaporation of acid. Moisture is to be deter- 

 mined in the air-dry soil by drying to a constant weight in a water oven 

 kept briskly boiling, and the acid-soluble materials are to be determined 

 in this dry soil, tlie results being reported on the air-dry basis. In the 

 method for the determination of sulphuric acid in soils,' the amount 

 of distilled water added in the first case is reduced to 50 cc, the amount 

 of barium chlorid added is reduced to 2 or 3 cc, and the amount of 

 boiliug water to be used in washing the barium-sulphate precipitate is 

 reduced to 15 to 20 cc. A few other unimportant changes, principally 

 of a verbal character, were recommended and adopted. 



It was especially recommended that the reporter for next year inves- 

 tigate the chemical methods of determining the availability of potash 

 and phosphoric acid in soils. 



In connection with the discussion of the subject of soils, a paper "On 

 the action of oxalic acid on phosphates, silicates, and soil," by J. H. 

 Castle, P. Marvin, and J. C. Calvert, was read before the association. 

 In this the results of treatment of several commercial phosphates of 

 lime, silicates of calcium and potash, feldspar, and soil are reported, 

 which show that comparatively large amounts of phosphoric acid and 

 potash are dissolved out of these substances by this reagent, and 

 indicate that oxalic acid is probably one of the strongest acids found 

 in root sap. By heating 10 gm. of soil with 100 cc. of normal oxalic 

 acid in a pressure bottle for G hours in a boiling water bath as much 

 phosphoric acid Avas dissolved as by the provisional juethod of soil 

 analysis, but slightly less of x)otash. It is believed that the amount of 

 the latter might be increased by mixing a stronger acid with the oxalic 

 acid. The advisability of using oxalates as a fertilizer, as indicated 

 by these tests, is pointed out, and it is stated that this subject will be 

 further investigated in pot experiments. 



' U. S. Dept. Agr., Div. of Cbem. Bui. 38, p. 203. 



