118 EXPERIMENT STATION RECORD. 



are giveu will make them available to anyone \Yho may be interested. lu 

 like manner practical applications of the results are merely indicated, as their 

 discussion can be more profitably given elsewhere than in this necessarily 

 technical description of a chemical problem." 



- The bulletin deals with the transformations of the different modifications 

 of calcium sulphate : the occurrence of calcium sulphate in nature; solubility of 

 the salt in water and in aqueous solutions of calcium sulphate and other calcium 

 salts, of electrolytes not containing a common ion, and of nonelectrolytes. and 

 calcium sulphate in salt deposits in alkali regions. It is presented as " a chapter 

 in the larger study of the chemistry of alkali," developing the theories ad- 

 vanced in Bulletin 17 of the Bureau (E. S. R.. 13. p. 2.32) as far as calcium 

 sulphate enters into the formation of alkali. 



Of the forms in which calcium sulphate exists, namely, hemihydrate, dihydrate 

 (gypsum), natural anhydrite, artificial anhydrite, gypsum and natural anhy- 

 drite occur together in nature and are the only forms which remain stable in 

 any solution. The solubility of calcium sulphate in water apparently reaches a 

 maximum at about 40° C, when about 2,100 parts per thousand go into solution. 

 The presence of other substances in solution affects the solubility of gypsum, 

 thus salts having a common ion depress the solubility, low concentration solu- 

 tions of electrolytes which do not have a common ion increase the solubility, 

 non-electrolytes differ in their effects. Solutions containing 48 parts per thou- 

 sand of sulphuric acid behave like water. These results make it quite clear that 

 the composition of the drainage water from alkali soils which contain a mixture 

 of various salts can not be predicted from the relative solubilities of the salts 

 present. 



Reclamation of alkali soils, C. W. Dorsey (T'. .S*. Dept. Af/r.. Bur. Soils Bid. 

 SJf, pp. 30, pis. .'/). — This bulletin defines alkali; discusses its origin and accumu- 

 lation in soils, its effect on crops, methods of preventing alkali accumulation, 

 treatment of alkali soils, including cultivation of alkali I'esistant crops, use of 

 chemical antidotes, and scraping, flushing, and flooding with and without 

 drainage to free soils from alkali; and gives an account of the alkali reclama- 

 tion experiments of the Bureau of Soils near Salt Lake City. Utah, Fresno. 

 Cal., North Yakima, Wash., Tempe, Ariz., and Billings, Mont., and a summary 

 of experience gained from these experiments, including possible injury to the 

 land by constant flooding, resulting water-logging of the soil, destruction of 

 tilth and loss of valuable fertilizing constituents, effect of hardpan in retarding 

 leaching, clogging of drains by roots and silt, depth and distance apart for 

 drains, and cost of reclaiming land by flooding and drainage. 



As regards the last two points, it is stated that " in practice it is not advis- 

 able to place drains less than 3 ft. deep, and depths of 4 or 5 ft. or more give 

 much better i-esults. 



" The distance apart at which drains should be placed depends largely on 

 the character of the soil. In heavy soils rapid reclamation may be accom- 

 plished with drains 100 to 150 ft. apart. In porous sandy soils the distance 

 may be greater, intervals of 250 to 300 ft. in many cases answering the purpose. 

 The less the interval between drains the more rapid can reclamation be carried 

 on. but the distances given above are conservative. 



"As to the cost of carrying on such reclamation, it has been found to depend 

 on the local conditions of each area. AYhile in the central portion of the United 

 States all sizes of drain tile are sold at reasonable prices, this is uot the case 

 in the West. . . . Even considering the exorbitant prices at which the farmer 

 must purchase his tile, it is still possible in the greater number of western dis- 

 tricts to provide an adequate drainage system for small tracts of land at an 



