1919J SOILS — FERTILIZERS. . 629 



mercial fertilizer, but in more conservative amounts than vs^as formerly used 

 for the ordinary farm crop." 



Potash recovery, N. H. Gellert (Chem. and Metall. Engin., 20 {1919), No. 7, 

 pp. 308, 309; abs. m Chefti. Abs., 13 (1919), No. 10, p. 1129). — A comparison is 

 made of d:ita reported by others, and estimates are given of the cost of oper- 

 ating the Cottrell system for the removal of the dust from blast furnace gases. 

 It is considered that the net revenue derived from the potash that Is recovered 

 in the dust should yield profitable returns even if the price of the potash were 

 to drop to a value of $1 per unit. 



Value of blast furnace dust as a potash manure: Report on field trials 

 (Jour. Bd. Agr. [London], 26 (1919), No. 4, pp. 387-396) .—Plat experiments 

 with potatoes and mangolds to compare low-grade dust, medium-grade dust, 

 high-grade dust, extracted dust, and German potassium sulphate containing 

 respectively 2.21, 5.85, 8.9, 7.37, and 50.24 per cent potash as sources of potash 

 are reported. The fertilizers were added at respective approximate rates of 

 2,200, 850, 550, 650, and 100 lbs. per acre. 



It was found that the extracted and high-grade dusts gave the best results 

 with potatoes, followed by the medium-grade dust and the potassium sulphate. 

 The low-grade dust gave the poorest results. It is noted that the extracted 

 dust, that is, dust very rich in potash from which the bulk of the water-soluble 

 potash had been removed by boiling water, gave among the highest results. It 

 was found to be advisable to add the dust well in advance of the crop owing 

 to the relatively low availability of the potash. 



The results obtained with mangolds did not correspond with those obtained 

 with potatoes. Potassium sulphate gave the best results, while the poorest 

 were with low-grade dust and late additions of medium-grade dust. The rest 

 of the dusts gave about equal results in all cases, with about a 10 per cent 

 increase in yield. 



Fertilizer from the effluent from potassium chlorid works, W. Hxjttneb 

 (Chem. Ztg., 1,2 (1918), pp. 434, 435; abs. in Jour. Soc. Chem. Indus., 37 (1918), 

 No. 21, p. 666A; Chem. Abs., 13 (1919), No. 9, p. 985).— In the process of manu- 

 facture of fertilizer from the eflluent of potassium chlorid works the effluent 

 is introduced into a tank containing quicklime, the latter being covei-ed with 

 the liquid. Heat is developed and the whole is converted into a powdery mass 

 which consists of magnesium oxid, magnesium and calcium oxychlorids and 

 small quantities of potassium chlorid, sodium chlorid, calcium sulphate, etc. 

 The fertilizing value of this material is said to depend chiefly upon the 

 presence of the magnesium oxid. 



Bracken as a source of potash, J. E. Purvis (Proc. Cambridge Phil. Soc., 19 

 (1919), No. 5, pp. 261, 262; abs. in Chem. Abs., 13 (1919), No. 15, pp. 1736, 

 1737). — The percentage of potash in samples of bracken collected at Cambridge 

 during different months of the year ranged in the dry material from 3 per 

 cent in that collected in June to 0.82 per cent in the samples collected in 

 October. In Welsh bracken the corresponding range of the potash was from 

 3.22 per cent to 1.32 per cent as found in the samples collected in July and 

 October, respectively. 



These results are considei-ed to confirm the opinion that in the summer 

 months there is more potash than in the later months. "Also there is a clear 

 indication that, on an average, the Welsh peaty soil yields more potash than 

 the Cambridge poor sandy soil." 



Bracken: Utilization and eradication, R. A. Berry (West of Scot. Agr. Col. 

 Ann. Rpt., 14 (1917), pp. i8i-193).— Studies on bracken with particular refer- 

 ence to its value as a source of potash are reported. 



