288 EXPERIMENT STATION EECORD. IVol. 35 



keeps the floating matters submerged and apparently results in all fecal matter 

 sooner or later becoming water-logged and sinking through the slot into the 

 sludge chamber. It is too soon to state with conviction the amount of digested 

 sludge that may be expected from small-scale tanks, but one tank indicates an 

 apparent accumulation of 2.6 cu. ft. per year per person and another tank 

 4 cu. ft. The only period during which the Imhoff tanks required daily atten- 

 tion was the foaming period, which lasted about ten days, and during which 

 time some of the foam had to be removed and buried. At all other times atten- 

 tion once a month at the most was ample. Since the foaming period has been 

 passed the scum formation has been slight. 



" The decomposed sludge obtained from the small-scale Imhoff tanks resem- 

 bled that obtained in large tanks except that it had a much higher moisture 

 content. This may perhaps be explained by the shallowness of the sludge layer. 

 A 15-in. sand bed dosed with settled sewage at a net rate of 190,000 gal. per 

 acre per day during the second summer reduced an average oxygen demand of 

 63 parts per million to 12 parts per million (24 hours, 20° C). This is probably 

 ample purification for many cases, but insufficient for others. The sand bed 

 required very little attention during the summer months, but what would seem 

 to be a prohibitive amount of attention during the winter months, even though 

 covered with a tongue-and-groove wooden cover. No nuisance was produced 

 during the summer months by the dosing of the uncovered sand bed with the 

 Imhoff tank effluent. The growth of weeds on the sand surface did not seem 

 to have an unfavorable effect upon the operation of the sand bed." 



A practical process for the sterilization and utilization of polluted water 

 in the field, Holland (Jour. Pharm. et Chim., 7. ser., 12 {1915), No. 6, pp. 179- 

 182, fig. 1; abs. in Chem. Abs., 10 (1916), No. 2, p. 236).— Water in a barrel is 

 treated with a sufficient excess of calcium hypochlorite of known strength to 

 impart a distinct chlorin taste. It is next passed into a large funnel contain- 

 ing absorbent cotton, and then upon a perforated disk with alternate layers of 

 finely powdered charcoal, fine sand, powdered charcoal, coarse sand, wood 

 charcoal, crushed stone, and straw to distribute the water. 



Dams and weirs, W. G. Bligh {Chicago: Amer. Tech. Soc, 1915, pp. [7///] + 

 206, figs. 124). — This is an analytical and practical treatise on gravity dams and 

 weirs, arch and buttress dams, and submerged weirs and barrages. It con- 

 tains the following chapters : Gravity dams, design of dams, unusually high 

 dams, notable existing dams, special foundations, gravity overfall dams or 

 weirs, arched dams, multiple arch or hollow arch buttress dams, hollow slab 

 buttress dams, submerged weirs founded on sand, and open dams or barrages. 



Good roads of Monroe County, New York, 1915, J. Y. McClintock {Roches- 

 ter, N. Y.: Co. Supt. Highways, 1915, pp. 48, pi. 1, figs. 86). — This is a report 

 of the county superintendent of highways for 1915, giving tabulated state- 

 ments of expenditm-es for highway purposes during the year and calling atten- 

 tion to the more important features of the work. 



Fourteenth annual report of the state board of public roads of the State 

 of Rhode Island {Ann. Rpt. Bd. Pub. Roads R. I., I4 {1916), pp. 60).— This is 

 a report of expenditures on road and bridge work in the State for 1915. 



Surface oiling of earth roads, B. H. Piepmeier {III. Highway Dept. Bui. 11 

 {1915), pp. 28, figs. 26; Sci. Amer. Sup., 81 {1916), No. 2102, pp. 250, 251).—'' It is 

 the purpose of this publication to present as many facts concerning the use of 

 oil as it is possible to secure at this time, also to describe what is shov.n by 

 experience to be the best method of preparing the road and applying the oil, 

 together with a few suggestions that may be of some assistance to the con- 

 tractor or individual who has such work under consideration. 



