886 EXPEEIMENl STATION EECORD. 



The results are taken to indicate that while the addition of alum immedi- 

 ately causes a considerable reduction in the available chlorin content the 

 disinfecting qualities of the bleach are not apparently affected under a period 

 of 12 hours. The addition of alum to bleach solutions did not have the effect 

 of lowering the bacteriological efficiency appreciably along with the reduction 

 of available chlorin during the first 12 hours, but after this period a perceptible 

 change in efficiency was evidenced. 



" The addition of varying amounts of alum does not cause results correspond- 

 ing to the amounts added. . . . The amount of chlorin in parts per million 

 appears to be reduced in direct proportion to the amount of alum added up to a 

 certain limit, after which the further addition of alum has little effect on the 

 available chlorin." 



American sewerage practice, L. Metcau and H. P. Eddy (Xew York and 

 London: McGraw-Hill Book Co., 1914, vol. 1, pp. X+lJfl, pis. 25, figs. 213; 1915, 

 vols. 2, pp. X-\-56Jf, pis. 18, figs. 163; 3, pp. XIII+851, pi. 1, figs. 229; vol. S rev. 

 in Engin. Neics, 7| {1915), Xo. 25, pp. 1168, 1169). — This treatise deals, in three 

 volumes, with the design and construction of sewers and with sewage disposal. 



The chapters of volume 1, Design of Sewers, are as follows: The lessons 

 taught by early sewerage works ; the general arrangement of sewerage systems ; 

 flow of water in pipes and channels ; velocities and grades ; measurement of 

 flowing water; quantity of sewage; precipitation; formulas for estimating 

 storm-water flow; the rational method of estimating storm-water run-off in 

 sewer design ; gaging storm-water flow in sewers ; sewer pipe ; the design of 

 masonry sewers ; examples of sewer sections and the loads on sewers ; the 

 analysis of masonry arches; street inlets, catch basins, and manholes; junc- 

 tions, siphons, bridges, and flushing devices; regulators, overflows, outlets, tide 

 gates, and ventilation; and sewage pumping stations. 



Volume 2 deals with the construction of .sewers, as follows: Preliminary 

 investigations; engineering work and inspection during construction; excava- 

 tion; machinery for trench excavation; methods of rock excavation; ex- 

 plosives and blasting; quantity and cost of excavation; rate of progress in 

 building sewers; the sheeting and bracing of trenches and tunnels; sizes of 

 sheeting, rangers, and braces; purcliasing, handling, and laying sewer pipe; 

 jointing sewer pipe ; construction of brick and block sewers ; construction of 

 concrete sewers ; profiles, templates, forms, and centers ; contracts, specifi- 

 cations, and drawings; technical specifications; operation and maintenance 

 of sewerage systems; and explosions in sewers. 



The chapters of volume 3, Disposal of Sewage, are as follows : Introduc- 

 tion — ^i^rogressive steps in sewage treatment ; meaning of chemical analyses ; 

 bacteria and their relation to the problem of sewage disposal ; plankton ; 

 composition of sewage ; theories of sewage disposal aJid treatment ; sewage 

 disposal by dilution; grit chambers; racks, cages, and screens; sedimentation, 

 straining, and aeration; tanks for sludge digestion; chemical precipitation; 

 sludge; contact bods; trickling filters; intermittent sand filtration; irrigation 

 and the agricultural utilization of sewage and sludge ; automatic apparatus for 

 dosing ; disinfection of sewage and sewage effluents ; and disposal of residential 

 and institutional sewage. 



With reference to sewage irrigation and the use of sewage and sludge for 

 fertilization, experience in this country and in Europe is reviewed and it la 

 stated that " the popular opinion of the value of sewage in agriculture is much 

 exaggerated. The fertilizing value of sewage is far less than is commonly 

 supposed, on account of the great dilution of the constituents serviceable to plant 

 life, nitrogen, phosphates, and potash, and, further, because only a part of these 

 substances is present in the sewage in a form suitable for fertilizing pur- 



