324 EXPERIMENT STATION RECORD. 



The present status of the manufacture of nitric acid from the air, F. Russ 

 (Ostcrr. Chriii. Ztii.. U (lil<)i>), ^<>- •-•-. l>n- -'"^ 2U.>) .—'\'\ni theory of the pro- 

 duction of nitric- ac-id by the oxidation of .-itmosplieric air under the action of 

 electrical discharges is brielly explained and the various processes which have 

 been devised to utilize this |)rinciple are referred to. 



The agricultural value of dried superphosphate, M. de Molinari and O. 

 LiGOT (Ann. V,vmhloH.r, Ji> (IHOU), ^o. U, pih GG3-669, ;)/.s. 2).— In pot experi- 

 ments with oats grown on soil and sand, ordinary superphosphate containing 

 15.07 per cent of phosphoric acid s(»lul)ie in alkaline ammonium citrate was 

 compared with the same superphosphate dried at 105° C. and containing 17.34 

 per cent of phosphoric acid soluble in alkaline ammonium citrate when pre- 

 cipitated with annnoniiim nitromolybdate but only 4.22 per cent when precipi- 

 tated with magnesia mixture by the direct method. 



The results in general confirmed those of previous experiments by the authors 

 and by Gregoire and Hendrick (E. S. R., 16, p. 32; 20, p. 726). They showed 

 that the drying of superphosphate at 165° C. increased the rate of assimilation 

 of the jihosphoric acid :ui<l indicated the accuracy of ordinary chemical meth- 

 ods (if deteniiiniiig the iiv;iil;ibility of piiosi)lioric iicid. 



On the utilization of tricalcium phosphate by Cruciferae, C. Ravenna and 

 M. Zamokani (Staz. fe'pcr. Agr. ItaL, .',.1 {Um)), No. 7, />/*. 389-396) .—Two 

 series of pot experiments are described in which the plants used were mustard, 

 vetch, and oats, and the cultures were made in pure quartz sand. In the first 

 series the plants were watered weekly with a nutritive solution containing per 

 liter of water, monocalcium phosphate 0.25 gm., calcium nitrate 1 gm., potassium 

 chlorid 0.25 gm.. magnesium sulphate 0.25 gm., potassium nitrate 0.25 gm., and 

 ferric chlorid trace. In the second series pure tricalcium phosphate was mixed 

 with the sand at the rate of 3 gm. per kilogram of sand, and the plants were 

 watered with a solution corresponding to the one described above except that 

 the monocalcium i)hosphate was omitted. 



Tables are given comparing the two series and the different plants, with 

 respect to the weight of the green plants, their weight in a dry state, the per- 

 centage of ash, the percentage of phosphoric acid in the ash, and the phosphoric 

 acid absorbed during cultivation. Six per cent more phosphoric acid was 

 absorbed by the mustard in the first series than in the second, but in the case 

 of vetch the increase was 24.3 per cent and with oats 43.1 per cent. 



Kainit and silicate of potash, Clausen (Lanclw. WchnW. Schles. Hoist., 

 59 {1909). Xos. J,7, pp. 801-80-'i; -'/S, pp. 821-823) .—Comparative tests of these 

 tv\'0 fertilizers by means of field and pot experiments with various crops, in- 

 cluding potatoes, buckwheat, peas, and clover, gave variable results but indi- 

 cated that in many cases kainit used in the ordinary way may prove positively 

 injurious. It is pointed out, however, that these injurious effects may be over- 

 come by proper use of the kainit in rotations of crops and that therefore the 

 results of these experiments should not be taken as bearing out Wein's con- 

 clusions (E. S. R.. 20, p. 822: 22, p. 24) as to the relative value of potash sili- 

 cate and other potash fertilizers. 



Field experiments to test the action of silicate of potash (phonolite) and 

 humus silicic acid, L. Hiltner and F. Lang iPrakt. Bl. Pflanzenbau u. Schutz, 

 n. ser., 7 (1909). Nos. 10, pp. 126-132; 11, pp. 139-151, dgm. 1; abs. in Illus. 

 Landw. Ztg., 29 (1909), No. 86, pp. 811-812). — Field experiments with oats and 

 potatoes indicate that humus silicic acid has a very slight direct fertilizing 

 value, but that under certain conditions it may increase the action of fertilizing 

 constituents already in the soil or added in the form of fertilizers. The phono- 

 lite was shown to have a certain fertilizing effect, but much less than that of 

 ordinary potash salts. 



