RECENT WORK IN AGRICULTURAL SCIENCE. 



CHEMISTRY. 



The determination of available phosplioric acid and potash in calcareous 

 soils, H. H. Corsixs and H. S. Hammond {Analyst, 28 [1903), No. 329, i>P- 338- 

 240). — The method of Dyer was found to give unsatisfactory results when used with 

 the highly calcareous soils of Jamaica. By following the practice advocated by Hil- 

 gard of neutralizing the carbonates in the soil before subjecting it to the solvent 

 action of the citric acid solution, results were obtained which agreed with the known 

 productiveness of the soil. 



The solvent action of the liberated carbon dioxid and of the neutral citrate formed 

 have been urged as objections to this modification of the method, but comparative 

 tests made by the authors on soils free from carbonates and on those to which car- 

 bonates were added showed that the solubility of the phosphoric acid remained 

 absolutely constant whether carbonates were added and neutralized or not. "As 

 regards jiotash, the figures indicate that in two cases the carbonic acid has exerted 

 an additional solvent action. Our experience in Jamaica leads us to doul)t whether 

 citric acid is an adequate detective solvent for all forms of potash in a soil available 

 for j)resent consumption by plants." 



On the determination of free phosphoric acid and the amount of this sub- 

 stance in superphosphates, A. D. Hekzfelder (Landw. Vers. ,Sl(tt., 58 [1903), No. 

 ,5-6, jip. 471-479). — The method of the association of German fertilizer manufactur- 

 ers, viz, titration of the water extract with soda solution, using methyl orange as an 

 indicator, is described, as well as the official Austrian method and that of ^Miintz, in 

 both of which free phosphoric acid is determined gravimetrically in the alcohol 

 extract. Comparative tests of the methods are reported and objections to all of them 

 are pointed out. 



The author proposes the following metho<l: Extract 1 gm. of the finely ground 

 substance in a Soxhlet apparatus with water-free ether for 10 hours. Evaporate the 

 ether and take up in about 20 cc. of water, evaporating to dryness and taking up in 

 water 3 times. Filter and wash with water slightly colored with methyl-orange as 

 long as a red color is observed. Usually from 100 to 150 cc. of water is required. 

 Titrate the filtrate with normal soda (?) solution, multiplying the number of cubic 

 centimeters used by 7.1 to get the percentage of fi-ee phosphoric acid present. 



A comparative study of French, P'nglish, German, and Hungarian sujierphosphates 

 with reference to water-soluble and free phosphoric acid showed the last two to be 

 nuich richer in free phosphoric acid than the French and English superphosphates. 



The quantitative determination of phosphates in the stomach contents, 

 G. H. A. Clowes {Auut. Jour. I'horni., 7-', {1903), pp. 325-330). 



A modification of Dumas' volumetric method of determining nitrogen, 

 R. Bader and A. Stohmann {Chem. 7A(j., 27 {1903), No. 52, pp. G63, 664, jig. 1; (ihx. 

 in t'heni, CentbL, 1903, II, No. 12, p. 740). — The principle of l.,ippman and Fleissner's 



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