1920] SOILS FERTILIZERS. 25 



concise review of present and future needs for nitrogen and of the advantages 

 eUiimed from the continuous operation of the Government nitrate plants to 

 lielp supply industrial and agricultural requirements. 



The commercial oxidation of ammonia, G. A. Perley {Jour. Indus, and 

 Engin. Chcm., 12 {1920), Nos. 1, pp. 5-16; 2, pp. 119-129, figs. 5).— This paper, 

 a contribution from the New Hampshire College, deals with the influence of the 

 more important factors involved in the oxidation of ammonia, and reports the 

 results of extensive research into the subject. 



The caking of sulphate of ammonia, C. G. Atwater and J. F. W. Schulze 

 {Chem. and Metallurg. Engin., 22 {1920), No. 8, pp. 373, 37/^).— Laboratory 

 experiments are reported which indicate that the impurity in ammonium sul- 

 phate causing caking is pyridiu sulphate. " This causes the sample to feel 

 moist to the touch, and due to its presence 5n the sulphate the latter will take 

 up moisture on damp days, only to lose it later with the decreasing humidity of 

 the atmosphere to produce a decided caking effect. The amount of water taken 

 up, as well as the resultant caking, is in proportion to the amount of pyridin 

 sulphate present. 



" By passing dry NH3 gas through samples containing pyridin sulphate, 

 pyridin is liberated and passes off. If the NH3 is preheated, quicker and more 

 thorough results are obtained. A treatment of the sulphate with very dilute 

 ammonia liquor produces practically the same effect and in some cases would 

 be more practical commercially. Ammonium sulphate may be produced by 

 either of these simple methods freed of a major part of its original pyridin con- 

 tent. In this state it will not absorb an appreciable amount of moisture from 

 the air and its caking Avill be negligible." 



Potassium nitrate from the Chilean nitrate industry, P. F. Holstein 

 {Jour. Indus, and Engin. Chem., 12 {1920), No. 3, pp. 290-293, figs. 2).— Methods 

 for the separation of the potash from Chilean nitrate are described, particu- 

 larly fractional crystallization, evaporation, and refrigeration. It is stated 

 that whatever method can be best used by a plant will depend on local con- 

 ditions. 



" The character of the ore and its potash content, the air temperature in 

 summer and winter, the composition of the mother liquor, and numerous other 

 factors must all be given consideration. Refrigeration will produce a higher 

 grade nitrate at a much lower cost than will evaporation. On the other hand, 

 evaporation, if properly carried out in the right type of evaporator, has the 

 advantage that tlie water removed from the system may be used as additional 

 wash water for washing the tailings in the boiling tanks, thus increasing the 

 recovery of sodium nitrate." 



It is noted that the average potassium nitrate content of all the nitrate 

 shipped from Chile is about 2 per cent. On this basis the production of potas- 

 sium nitrate in Chile during the year ended June 30, 1918, was about 130,000,000 

 lbs., representing about 30,000 tons of potash, or about 21 per cent of the total 

 consumption in the United States. 



The formation of the double salts of calcium and potassium sulphates 

 at 100° C, E. Anderson and R. J. Nestell {Jour. Indus, and Engin. Chem., 

 12 {1920), No. 3, pp. 243-246, fig. i).— Tests made, apparently in connection' 

 with the recovery of potash in cement mills, to determine the equilibrium con- 

 centration of potassium sulphate in solution in contact with solid gypsum and 

 potassium penta-calcium sulphate on the one hand and solid syngenite and 

 potassium penta-calcium sulphate on the other, at 100° C, indicate that these 

 concentrations are " 1.05 moles of K2SO. per 1,000 moles H2O for the former and 

 9.26 nioles of K2SO4 per 1,000 moles H2O for the latter equilibrium. The corre- 



