SOU.- b'EBTILIZEBS. 953 



The results in general, therefore," show thai the silica and manganese contained in 

 Thomas slag are of considerable importance as fertilizers. On the other hand there 

 was apparently some superiority of the phosphoric acid of the tetraphosphate over 

 thai of the silicophosphate, bul this is to be further studied. 



Comparative experiments with high percentage and low percentage Thomas 

 slag i Deut. Jxmdw. Presse, 82 | 1905), No. 79, pp. 667 669, figs. i). Plal experiments 

 with rye and oats, using equal money values of the two Blags (the low-percentage 

 slags containing not more than 5 per cent of citric-acid Boluble phosphoric acid), 

 showed the high-percentage phosphate to be more economical. See also I - l; . 

 16, p. L064. 



Citric-acid soluble phosphoric acid in Thomas slag, M. de Molin \i:i and < >. 

 Ligot i Bul. Agr. [Brussels], .", I 1905), No. 5, pp. 909 916; 6, pp. 1116 1118).- Com- 

 parative pol tests of untreated Thomas slag and thai which had been exhausted with 

 citric acid according to the Wagner method arc reported. The results show thai the 

 yield of oats was normal with the untreated Blag bul practically nil with the extracted 

 slag. 



Phosphate mining in Tennessee, I >. S. Cooke (Amer. Fert., 28 (1905), No. 5, 

 pp. 5-10, figs. 8) . This article discusses the rapid growth of this industry, some of 

 the difficulties encountered in developing it. the peculiarities of laborers, and the 



present outlook. 



Algerian phosphate and apatite (Mitt. Deut. Landw. Gesell., 20 1905), No. f6, 

 pp. 889-891). — This is a summary of experiments bySoderbaum in Sweden, compar- 

 ing the composition and fertilizing value of Algerian phosphate and Norwegian 

 apatite when applied to oats grown on sandy soils and peas grown on moor soils. 

 The results show in general the superiority of the Algerian phosphate. 



Experiments on the assimilation of potash and soda by plants, T. Pfeiffek 

 et u.. i Mitt. Landw. Inst. Breslau, 8 (1905), No. ',. pp. 561 618; abs. in Chem. Ztg., 80 

 (1906), No. 10, Repert. No. .'./>/'■ 25, 26).' — The numerous investigations on this sub- 

 ject which have been made in recent years are referred to. 



A series of pot experiments made during L903 and 1904 on barley with potash- 

 containing and potash-free artificial zeolites i potassium, sodium, and calcium zeolites 

 is reported, the object of the experiments being to study the capacity of plants to 

 utilize the potash of such compounds, the influence of potash-free zeolites on the 

 utilization and the fixation of the potash salts applied with them, and the extent to 

 which applications of sodium salts overcome the unfavorable action of potash-free 

 zeolites. The zeolites and necessary basal fertilizers were applied to pots contain- 

 ing 4 kg. of sand. The yield and potash and soda content! of the total crop, straw , 

 and grain are recorded. 



The results show that the potash of zeolites was readily utilized by the plant (as 

 high as 88 per cent (. The potash contenl of the grain remained fairly constant, bul 

 that of the straw varied widely with the amount of potash available for the uses oi 



the plant. The action of potash fertilizers was somewhat reduced by applying them 



in connection with Bodium and calcium zeolite-, thus indicating some fixation oi the 

 potash m less available forms, [ncreasing the applications of potash lowered the 

 sodium content of the plants. Incidentally it was observed thai sand which had 

 been treated with soda solution and hydrochloric acid yielded more potash and Boda 

 to the plant- than that which had not been treated. 



The indirect action ol soda OH the utilization of potash, which the experiments 



indicate, is ascribed to an exchange of bases. In case of -oils rich in potash this 

 exchange of bases may resull in a sufficient supply of potash to crops for a number 



of years. It is. however, a species of sod robbery and will ultimately result in pot- 

 ash exhaustion. The same i- true of the continuous use of potash -alts rich in sodium 



chlorid, although in tins ca.-e exhaustion is no1 bo rapidly brought about 



