824 EXPERIMENT STATION RECORD. 



It is thus seen that tlie retrogression of phosphoric acid in superphos- 

 phates is very largely dependent upon the free phosphoric acid present. 

 Aluminum salts do not behave like iron salts in superphosphate, but 

 like the salts of lime and magnesia. 



Pot experiments with barley on a fertile soil containing 0.63 per cent 

 calcium carbonate and 2 per cent of humus and treated with different 

 phosphates of calcium, aluminum, and iron showed that the effect of 

 the acid phosphates of these elements was almost the same. The tri- 

 basic phosphates were about one-half as effective as the acid phosphates. 

 The effect of the normal reverted phosphates was about one-half greater 

 than that of the tribasic phosphates. 



These results were obtained with a soil comparatively poor in lime 

 and humus. Iu a soil containing more than 5 per cent of calcium 

 carbonate, the acid phosphate would be rapidly transformed into tri- 

 basic phosphates, while if free phosphoric acid is present it forms nor- 

 mal phosphates. 



If the soil contains a large quantity of humus, the reverted phos- 

 phates are converted into readily soluble and assimilable forms. 



Pot experiments with barley on a soil containing 20.2 per cent of 

 humus and 0.31 per cent of lime showed the reverted phosphoric acid 

 to be in this case almost equal to the water-soluble. 1 



Are the compounds of phosphorus and sulphur found in moors 

 and -which are insoluble in strong acids also present in moor 

 plants? M. SCHMOEOKER (Landw. Jahrh., 26 (1897), No. 4-5, pp. 549- 

 554; abs. in Chem. ZU/., 21 (1897), No. 93, Repert.,p. 281). — Determina- 

 tions were made of the phosphorus and sulphur in moor grasses by 

 treating the fresh and dry plants and the ash of the plants with strong 

 hydrochloric acid. The amounts of phosphoric acid found were: In 

 fresh plants 0.13 per cent, in dry plants 0.228 per cent, in ash 0.2G7 per 

 cent. Similar results (0.105, 0.212, and 0.213 per cent, respectively) 

 were also obtained by treating the moor soil in the same way, and the 

 author concludes that the difficultly soluble phosphorus compounds of 

 such soils are also present in the plants growing on them. Determina- 

 tions of sulphuric acid showed a slight increase of this substance solu- 

 ble in acids on drying, but a decided increase when incinerated. 



Fertilizers — barnyard manure and chemical fertilizers, L.Caille {Les engrais; 

 h: fumier de ferme et les engrais cMmiques. Montpellier: Camille Coulet, lS97,i>p. 211, 

 figs. 5). — This is a popular discussion of the subject from the standpoint of French 

 agriculture. The book is divided into three parts — barnyard manure, chemical fer- 

 tilizers, and formulas for chemical fertilizers. The third partis of especial interest, 

 because it recommends and explains a series of fertilizer formulas adapted to the 

 principal farm crops. The objections to the recommendation of specific fertilizer 

 formulas are explained, but it is claimed that the use of such formulas is preferable 

 to blind use of factory mixed fertilizers. 



In preparing these formulas two classes of soils are taken into consideration — cal- 



1 See also Mitt. Ver. Ford. Landw. Versuchsw. Oesterr., 1893, No. 8, Part II, p. 140 

 (E. S. R., 5, p. 1015) ; and Landw. Vers. Stat., 45 (1894), p. 161 (E. S. R., 6, p. 626). 



