296 EXPERIMENT STATION RECORD. 



of soil carbonates is to be made, comparing (1) the Marr method (E. 8. K., 22, 

 p. 511) with methods which involve the use of dilute hydrochloric acid and coi - 

 stant aspiration of air with and without heating, and (2) the wet combustion 

 method witli a mixture of chromic and sulphuric acids for estimating organic 

 carbon with the combustion of the soil in the furnace, as well as of the 

 Hutchinson and MacLennan method for determining the lime requirements of 

 the soil. The official method for carbon dioxid is to bo eliminated. 



C. B. Lipman, referee on nitrogenous coustitnonts of soils, expressed the 

 opinion that the association has been giving considerable time to the study of 

 methods for soil chemical work which are already well established, while the 

 study of some of the methods now in use which need much improvement has 

 been neglected. The methods for nitrites and nitrates and for ammonia, as 

 adopted for water in 1913, were accepted as official methods for the determina- 

 tion of these constituents in aqueous soil extracts. 



W. H. Mclntire gave a brief account of a new method for determining the 

 lime requirement of soil. In the method 10 gm. of soil is sifted through a 

 100-mesh sieve and heated with 100 cc. of a specially prepared calcium carbon- 

 ate solution to a paste, the jiaste transferred by means of carbon dioxid-free 

 distilled water to a flask and shaken with 5 cc. of 85 i)er cent phosphoric acid 

 solution in a special device, and the liberated residual carbon dioxid collected 

 in a 4 per cent sodium hydroxid solution contained in a Camp absorption tower. 

 The amount of calcium carbonate in the carbonate solution is determined by 

 backing off the excess of dissolved gas and decomposing the precipitated car- 

 bonate by the above procedure. The difference between the added and the 

 residual calcium carbonate in the soil is tlien determined, a correction being 

 made for the carbon dioxid in the air of the apparatus and the carbonate in 

 the sodium hydroxid solution. 



G. S. Fraps gave a paper on the interpretation of soil analyses which in- 

 cluded a discussion of the various methods of analysis and the benefits to be 

 derived therefrom. Experience has sho^NTi that pot experiments do not always 

 confirm the chemical analysis, and the ix)t experiments are themselves open to 

 irregularities. Standards of interpretation on the basis of the corn plant, how- 

 ever, will show the relative deficiencies of the soil in plant food. 



The associate referee's report on alkali soil, given by R. F. Hare, consisted 

 of a comparison of methods now in common use for the analysis of alkali soils. 

 A number of analyses of New Mexico soils taken from a region in which black 

 alkali is the dominant type were presented, followed by a review of some of the 

 methods for the determination of alkali in soils. The association's method for 

 alkali waters was provisionally adopted for alkali soils. 



A cooperative study was reported by R. C. Roark on the determination of 

 moisture, carbon dioxid, copper, jirsenic, and lead o.xid in Bordeaux mixture, 

 Bordeaux-lead arsenate, and Bordeanx-I'aris green, and comi)aring new methods 

 for nicotin, and of arseuious oxid in Paris green with the ottit-ial method. The 

 oflicial, C. M. Smith, and C. C. Hedges methods for tot.il arsenious oxid in 

 Paris green did not agree as closely as might be expected, and even the official 

 method varied nearly 2 per cent. With a modification described both the Smith 

 and Hedges methods gave better results. Methods for total arsenic present as 

 ASsOa and AssOi^, and as As-^^Os only, are proposed to displace those for total 

 arsenic and water-soluble arsenious oxid. 



The results with Bordeaux mixture (dry and paste) included those for copper 

 (electrolytic and thiosulphate methods) and moisture. Good results were ob- 

 tained in general hy the analysts, but little work was done by the electrolytic 

 method. With Bordeaux-Paris green the results for copi^er by the thiosulphate 

 method, carbon dioxid, and moisture agreed very well, but total arsenic varied 



