428 EXPERIMENT STATION RECORD. [Vol.36 



Studies of the solubility of phosphoric acid in potted soil, of phosphates after 

 addition to soil, and of phosphoric acid occurring naturally in Hawaiian soils, 

 as indicated by treatment with several reagents, indicated that " hydrochloric 

 acid of official strength does not dissolve all of the phosphoric acid of Hawaiian 

 soils. To determine the total phosphate content, it is necessary to fuse the soil 

 with sodium carbonate. Fifth-normal nitric acid has very little solvent action 

 upon the phosphate in the soils, indicating the absence of appreciable quan- 

 tities of calcium phosphate. One per cent citric acid has a much stronger 

 solvent action than fifth-normal nitric acid. Of the weaker solvents, 1 per cent 

 sodium hydroxid is the strongest, due to its action on the iron and aluminum 

 phosphates. The fertilizer (phosphate) requirement of the soil is not measured 

 by solubility in water or fifth-normal nitric acid, but it may be indicated by the 

 solubility in citric acid. The solubility of a phosphate before it is added to a 

 soil can not be used as a criterion of its solubility after addition, but it may 

 indicate its availability. The fixation of a soluble phosphate by the soil may be 

 influenced by the basicity of the soil. Availability as determined with solvents 

 does not agree in full with that indicated by plant growth." 



A description of a modification of the official method used in determining the 

 phosphoric-acid content of Hawaiian soils by reason of the high titanium content 

 is appended. See also a previous note (E. S. R., 35, p. 503). 



Phosphate fertilizers, B. Suthkrland (Proc. Roy. Soc. Victoria, n. ser., 28 

 {1916), No. 2, pp. 208-210). — Field experiments on 1/200-acre plats with early 

 and late wheat and oats are reported. The purpose was to compare sodium 

 orthophosphate, sodium pyrophosphate, and trimetaphosphate with each other 

 and with superphosphate when used in amounts equivalent in phosphoric-acid 

 content to 100 lbs. of superposphate per acre. 



It was found that metaphosphate gave in all cases a better crop than super- 

 phosphate, but with some plats the difference was practically negligible. Pyro- 

 phosphate was in every case less satisfactory than superphosphate. Meta- 

 phosphate applied as a top-dressing in spring did very little good. Apparently 

 the value lay in the initial start to the very young plant. In the case of brown 

 oats, which grew rapidly, the advantage of using metaphosphate was very 

 marlied. 



The citric acid solubility of the phosphate in Thomas slag, P. Keoix 

 (Ztschr. Angew. Chem., 29 {1916), I, pp. 199, 200; abs. in Jour. Chem. Soc. 

 [London^, 110 {1916), No. 645, II, p. S89; Chem. Abs., 10 {1916), No. 20, p. 

 2608). — It was found that the addition of sand in the converter raised the 

 citrate solubility of the phosphoric acid in Thomas slag on the average by about 

 1 per cent. The amount of soluble phosphate seemed to have a tendency to 

 remain constant for each particular type of slag and to be more or less inde- 

 pendent of the total amount of phosphate present. This constant was about 

 18.5 per cent for sand slag and 17.3 per cent for normal slag. 



Tlie conservation of phosphate rock in the United States, W. C. Phajlen 

 {Bui. Amer. Inst. Mining Engin., No. 119 {1916), pp. 1901-1934. figs. 6).— This 

 report deals with the production, exportation, and conservation of phosphate 

 rock In the United States, describes substitutes used therefor, and describes 

 domestic and foreign deposits, especially those of Florida and Tennessee and of 

 Africa and the southern Pacific Ocean. 



The salt and alkali industry, G. Martin, S. Smith, and F. Milsom {London: 

 Crosby Lockwood d So7i, 1916, pp. VIII+100, pi. 1, figs. 36).— In addition to 

 chapters on the manufacture of common salt, hydrochloric acid, sodium sul- 

 phate, and sodium carbonate, two chapters are included on the Stassfurt salt 

 industry and on potassium salts in general. 



