416 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



The bone meal and hoof meal gave a slight increase in phosphoric acid (P0 4 ). 

 The hoof meal yielded more nitrate than the bone meal. 



Decomposition of dried blood was found to take place more rapidly in open 

 sandy soil than in close-textured soil (heavy silt loam). 



The writer concludes that the soil solution obtained by this method furnishes 

 a better means than other methods of studying what is lacking in the soil for 

 the plant. — F. G. A . 



Soils, Oxidation of Sulphur in. By O. M. Shedd (Jour. Agr. Res. xviii. 

 No. 6, Dec. 1919, pp. 329-345). — The author found that comparatively large 

 amounts of added sulphur are easily oxidized to sulphuric acid in the soil, and 

 it appears that this acid would act upon the rock phosphate when present 

 and convert it into a water-soluble form. The time of contact of the sulphur, 

 soil, and rock phosphate was about 10 weeks. Further experiments with rock 

 phosphate, sulphur, soil, and manure show, after 24 months, that about 17 per 

 cent, and 84 per cent, of the total phosphorus had been converted into a water- 

 soluble and ammonium citrate-soluble form respectively. This does not proceed 

 as rapidly as when an inoculation is made with a sulphofying organism. When 

 this is added, the time is reduced nearly one-third. Nitrification can proceed 

 regardless of the acid formed by the sulphur oxidation. The amounts of nitrogen 

 found to be nitrified was about 20 per cent, of the total. Sulphofication was 

 found to take place in all soils examined. When 25 and 50 mgrms. of sulphur 

 were added to 100 grms. of soil, about the same percentage of the total was 

 oxidized in a given time. The best conditions to promote the reaction are initial 

 inoculation, high temperature, thorough aeration, and moisture. The acid 

 phosphate made by this procedure was equal to the commercial product, as far 

 as physical condition is concerned. It is possible that, by further simplification 

 of the process, it may prove of immediate practical application. — A. B. 



Soils, Rarer Elements in. By W. O. Robinson, L. a. Steinkoenig, and C. F. 

 Miller (U.S.A. Bur. of Soils, Bull. 600, Dec. 1917, pp. 1-28; 3 figs.). — Some of the 

 rarer elements closely resemble the commoner ones in chemical reaction. 

 Vanadium resembles phosphorus, rubidium resembles potassium. If a certain 

 element, present in small amounts only, is absorbed by a particular species of 

 plant in relatively large quantities and occurs in other plants in traces only, 

 it is reasonable to assume that the element has some physiological function. 

 In the present paper, titanium, vanadium, chromium, molybdenum, barium, 

 strontium, lithium, rubidium, caesium, have been determined in soils and in certain 

 plants. Lithium was found in spectroscopic quantities in all plants examined. 

 Rubidium was present in majority of cases. Caesium was found in ash of timothy, 

 raspberry, and beet from certain areas. Chromium was occasionally found in 

 very small quantities only. Vanadium was found in six cases as traces only. 

 Molybdenum was not found in any of the plants studied. Barium was present 

 in all cases, but strontium was only found in peas, tomato, wheat, alfalfa, not 

 in beans. Titanium was present in small quantities in all cases, while aluminium 

 was found in large quantities in all but two instances. 



There is no evidence that vanadium replaces phosphoric acid in its functions in 

 plants. Rubidium and caesium are apparently absorbed by the plant when 

 present in soil solution. There is no evidence to show that any of these rarer 

 elements are of value as fertilizers. 



Details of analytical methods are set out as an appendix. — A. B. 



Soils, Relationship between the Unfree Water and the Heat of Wetting 



of, and its Significance. By G. J. Bouyoucos (U.S.A. Exp. Stn. Mich., 

 Tech. Bull. 42, Mar. 191 8, pp. 23 ; 3 tables). — The writer finds that 

 there exists a real relationship between the " combined water " in the soil (i.e. 

 the water which refuses to freeze even at — 78 0 C.) and the " heat of wetting " of 

 the soil (i.e. the heat generated by the addition of water to dry soil). The 

 magnitude of the heat of wetting is generally very large, especially in some clay 

 loams and clays, where it was found to be over 400 calories, and in peat over 

 1 100 calories, per 50 grams substance. This comparatively tremendous amount 

 of heat represents energy expenditure at the expense of the water only, and is 

 the result of the water undergoing a transformation from its liquid state of 

 aggregation to a solid state of aggregation. 



The difference in the heat of wetting of soils and various artificial materials 

 in different liquids indicates that the attraction or affinity of the different 

 solid materials for the different liquids is specific or selective. 



It appears to be generally true that when a solid material is immersed in a 

 liquid for which it has only a small attraction or affinity, and a second liquid 



