218 EXPERIMENT STATION RECORD. [Vol.37 



Potash in agriculture, B. C. Aston (Jour. Agr. [New Zeal.], 11 {1915), No. 

 i, pp. 28S-295, figs. S; IS {1916), No. 6, pp. U6-454).—This is a review of the 

 natural sources of potash in New Zealand, from which it is concluded " that 

 only for special crops, such as potatoes, garden crops, mangels, and a few other 

 potash-loving crops, are New Zealand soils immediately in need of potash 

 manuring, and it is with these crops and with reclaimed swamps deficient In 

 potash that experiments might be instituted to determine whether the deficiency 

 may be economically supplied by resources available in the Dominion. Re- 

 searches having as their object the extraction of potash with a view to its 

 export might well give place to others having a greater prospect of economic 

 success." 



The volatilization of potash from cement m^aterials, E. Andebson and R. J. 

 Nestetx {Jour. Indus, and Engin. Chem., 9 {1917), No. S, pp. 25S-261, figs. IS). — 



The results of an extended series of investigations on potash volatilization 

 from silicate mixtures are reported, which are taken to Indicate that " the 

 potash in any cement material can all be volatilized. The determining factors 

 in this reaction are temperature and the length of time exposure of the cement 

 material to the temperature and gas volume prevailing. The lower limit of 

 temperature for potash volatilization is 1,100° C, and the rate of volatilization 

 increa.ses rapidly with the temperature. 



" The presence of chlorids, particularly calcium chlorid, increases the velocity 

 of the volatilization, while sulphates deorea.se this rate. Because of the forma- 

 tion of sulphate.s, sulphur dloxld in the furnace ga.ses retards tlie volatilization. 

 Sodium is driven off nearly as easily as is the potassium. 



" In the kiln, besides the factors of time and temperature, the size of the 

 clinker also affects the volatilization rate. The smaller the clinker the better 

 the volatilization of potash from It. 



"Although the potash in any cement mix can be driven off, the rate of ex- 

 pulsion at any given temperature varies for different materials, and is prob- 

 ably dependent on the niincralogical character of the potash-bearing cotnponent 

 of the cement material." 



Growing crops without potash in 1916. C. D. Woods {Agr. of Maine, 1915. 

 pp. 29S-S07). — This paper is a reprint of that previously noted (E. S. R., ?>'k 

 p. 325). 



Lim.e in agriculture, E. A. Fki.deu {S. C. Dcpt. Agr., Com. and Indus., Bui. 

 59 {1917), pp. 75, figs. 2). — This bulletin is intended to be a complete treatise 

 on the subject, discussing the varied forms of agricultural lime and their uses, 

 sources of supply, and the relative values of limestone, shell lime, calcined marl, 

 and noncaustic, dried phosphomarl in South Carolina agriculture. It is stated 

 that liming is the greatest need of South Carolina agriculture and that marl is 

 the greatest undevelojied asset of the State in this re.spect. Special attention is 

 given to the Intelligent use of lime. 



Forms of agricultural lime and their application. M. L. Fk.^bnow {Nat. 

 lAme Manfrs. Assoc., Agr. Bill. S {1917), pp. 16). — This pamphlet deals with 

 ground limestone, quicklime, and hydrated lime with reference to their advan- 

 tages and disadvantages for agricultural u.se, pointing out especially the condi- 

 tions under which each may best be used. 



The relation of lime to agriculture, L. B. Brouohton {Md. Agr. Ext. Serv. 

 BtU. 2 {1916), pp. 25-56). — This bulletin discusses different lime-bearing com- 

 pounds and their physix^l, chemical, and biological effects on soil, and sum- 

 marlzei? the re.sults of experiments at the Maryland Experiment Station on the 

 effect of lime in increasing crop production. 



The summarized results are taken to indicate that " physirnlly even a small 

 amount of lime carbonate by its solubility in the carbonated soil water will act 



