616 EXPERIMENT STATION RECORD. 



probably be to cause a teiuporary increase in the rate of flood flow, and, 

 eventually, a permanent decrease in the i-ate of flood flow." 



Note on subsoil water in Eg-ypt, H. T. P'errar {Cairo 8ci. Jour., 3 (t!)09). 

 No. 2S, pp. l-J/, (Iff ins. 2). — These notes are based upon a series of observations 

 made by means of experimental wells in a number of localities, mainly in 

 Upper Egypt. These observations showed a close relation between the flood 

 stage of the Nile and the level of the water table in the soil. " In the basin 

 lands the range of fluctuation amounts to as much as 6 or 7 meters, in the 

 perennially irrigated areas it is only 3 or 4 metei'S, while in Lower Egypt it is 

 still less and is seldom more than a meter and a half. . . . The rise does not 

 take place until some 45 days after the Nile has begun to rise and the water of 

 these wells continues to rise for about the same number of days after the crest 

 of the flood has passed." 



Further notes on subsoil water in Egypt, H. T. Ferrar (Cairo Sci. Jour., 

 3 (1909), No. 39, pp. 291-29',, dgms. ;^).— The observations reported in this 

 article were made in a number of experimental tube wells in the Province of 

 Gharbia in Lower Egypt, where the land is irrigated perennially. The results 

 show that the conditions in Lower Egypt are almost the reverse of those in 

 Upper Egypt (see above) in that while the annual rise of the underground 

 water due to the Nile flood may be recognized in some of the wells, " the 

 greater number seem to be influenced by artificial irrigation more than by the 

 natural fluctuation of the subsoil water." 



Pure water (Mo. Bui. N. Y. State Dept. Health, 26 (1910), No. 1, pp. 3-27).— 

 This is a series of short special articles dealing with the question of keeping 

 water supplies pure or purifying polluted waters. 



The papers and their authors are as follows: The Department's Policy — 

 Past, Present, and Future, by E. H. Porter; Our Laws to Prevent Pollution of 

 Streams, by A. H. Seymour ; Disease from Impure Waters, by W. A. Howe ; 

 Responsibility of the Small Community in Preventing Stream Pollution, and 

 Sewage Disposal of the Community, by T. Horton ; Sewage Disposal of the Indi- 

 vidual Residence, Country Home, and Camp, by H. B. Cleveland; Inspection 

 of Watersheds, by H. N. Odgen ; Laboratory Control of Water Supplies, by 

 W. S. Magill; and The Effects of Water Pollution as Reflected in Vital Sta- 

 tistics, by F. D. Beagle. 



A convenient portable apparatus for measuring' the electric conductivity 

 of waters, sewag'e, and salt solutions in place, M. Pleissner (Wasser u. 

 Abtvasser, 2 (1910), No. 6, 249-256, figs. 3). — ^Apparatus based upon the use 

 of an alternating current, a Wheatstone bridge, and a telephone is described. 



SOILS— FERTILIZERS. 



On the chemical decomposition of rocks, J. Dumont (Compt. Rend. Acad. 

 Sci. [Paris], 1J,9 (1909), No. 26, pp. 1390-1393; ahs. in Rev. Sci. [Paris], 

 48 (1910), I, No. 2, p. 61). — A study of the action of carbon dioxid, pure water, 

 hydrochloric acid, and calcium chlorid on the decomposition of certain rock 

 types is reported. 



The results showed that pure rocks reduced to a powder were very slowly at- 

 tacked by acid or saline solutions. The limit of solution was very small and was 

 directly dependent upon the fineness of the material and the degree of change 

 which it had previously undergone. It was observed that notwithstanding the 

 effects of long continued culture the sandy particles of soil had preserved their 

 mineralogieal character to such a degree that a cultivated soil examined under 

 the microscope seemed to be a rock powder, the particles of which were 

 cemented together by a relatively small quantity of mineral and humic colloids. 



