- 156 - 



WILLIAM RALPH BALDWIN-WISEMAN. The increase in the Na- 

 tional Consumption of Water. (Reprinted from Journal 

 of the Royal Statistical Society. Vol. 72, part. II, 1902). Lon- 

 don 1909, pp. 58. 



H. S. SHELTON. The correlation of rock and river-water ana- 

 lyses. The Chemical News. August 12, 1910, N. 2646, p. 75. 



XIII. 



Geology in its relation to agriculture. Weathering of rocks 

 and soil formation. Land-preservation. Soil classification. 

 Mechanical and chemical composition of soils. Soil-physics. 

 Mineral constituents of soils. Humus and the nitrogenous 

 compounds of soils. Soil-bacteria and their transforming 

 action. Nitrogen fixation and nitrogen transformation and 

 dispersion in soils. Action of earthworms and other orga- 

 nisms in the soil. Fertility. 



F. S. MARK. Estimation of Calcium Carbonate in Soils. [Ro- 



thamsted Experiment Station] . The Journal of Agricultural 

 Science^ Vol. Ill, Part 2nd, October 1909, pp. 155-160. 



The estimation of calcium carbonate in certain soils character- 

 ised by their high humus content and their acid reaction to litmus 

 paper leads to some abnormal results. The boiling with acid at atmos- 

 pheric pressure decomposes organic matter in the soil with evolution 

 of carbon dioxide, and thus renders the results obtained for car- 

 bonate too high. In soils containing less than i/ of calcium car- 

 bonate and especially in acid soils the error introduced by thus 

 boiling with acid may be very considerable. For most soils 5 cc. 

 of strong hydrochloric acid to 100 cc. of water will be found conve- 

 nient; for acid soils and those containing low percentages of car- 

 bonate 2 cc. in about 100 cc. of water. As a rule, the weaker the 

 acid used, the better, so long as it is in fair excess. 



