1918] BUBAL ENGINEEEING. 85 



consists of a white porcelain boM'l, a cylindrical iron tank of 100 gal. capacity, 

 sufficient white enamel pipe for ventilation purposes, and 30 lbs, of an electro- 

 lytic caustic soda for chemical. The bowl is so constructed that solids do not 

 strike the bowl, but fall directly into the tank below. 



It was found by a series of experiments that 24 hours after the addition of 

 fecal matter all traces of bacterial life had disappeared, the solids had been 

 digested, and only a small amount of flocculent sludge was left out of solution. 

 During the reaction a small amount of ammonia gas was given off, but the 

 ventilation provided prevented the escape of any odor into the room. Analyses 

 of the solution in the tank showed that in 100 gal. there were i lb. of potash, 

 J lb. of phosphoric acid, and i lb. of nitrogen, all in a form available as plant 

 food. A warning is given that if a charge of chemical is not maintained this 

 system will be a nuisance. 



Chemical closets {Pub. Health Rpts. \_V. S.], S2 (1911), No. 26, pp. 1011- 

 1020). — In a brief statement of the advantages and limitations of chemical 

 closets it is pointed out that " everything depends upon the sufficiency of the 

 disinfection and the means of final disposal. No system should be installed 

 or recommended for installation in the absence of definite and satisfactory 

 evidence that the treatment proposed will in fact destroy pathogenic bacteria, 

 and, in those sections of the country where hookworm disease is prevalent, the 

 eggs and larvse of hookworms. While the design and satisfactory operation of 

 such a device is quite possible, its general adoption ought not to be recom- 

 mended without giving the fullest consideration to the possibilities of mis- 

 management, and it is believed that, whatever means are adopted for final 

 disposal, these should be so safeguarded that the almost Inevitable failure at 

 times of the chemical toilet may not result in serious danger to the health of 

 those affected." 



Sewag'e purifi.cation. — Decantation, H. VEERii:RE {Ann. Fonts et Chauss^es, 

 9. ser., 31 {1911), pt. 1, No. 1, pp. 1-151, figs. SI). — This is an extensive report 

 of experiments at the ]\Iesly experiment station in France on sedimentation as 

 a factor in sewage purification. 



Results of operation of small sewage-disposal plants, L. C. Frank {West. 

 Engin., 8 {1911), No. 1, pp. 210, 27i ) .—Experiments conducted by the U. S. 

 Public Health Service on the operation of small sewage-disposal plants con- 

 sisting of an Imhoff tank and sand bed are reported. 



" Sewage was tested from two sources. The sewage subjected to the most 

 careful test was from 25 people comprising a nurses' dormitory and one resi- 

 dence. . . . The sewage flow was 100 gal. per capita daily. The occasional 

 samples of raw sewage gave an average value somewhat over 1,000 parts per 

 million total solids and 177 parts per million for a 24-hour, at 20° C, oxygen 

 demand. The other sewage used for testing was from 60 people in a small 

 community in Chevy Chase, Md." The following conclusions are considered 

 justified : 



" It is possible by means of a 5-hour detention period in a properly designed 

 Imhoff tank to remove from the raw sewage of smaU communities 98 per cent 

 of the settleable solids without producing a nuisance. A mean detention period 

 of 6 hours, based on the average daily flow, will not cause the sewage to become 

 septic or foul-smelling if it is fresh when it enters the tank. The accumulation 

 of a disagreeable mass of grease and fecal matters in the first compartment of 

 the settling chamber may be prevented by the introduction of a horizontal 

 coarse-mesh screen at the water level of this chamber. The screen keeps the 

 floating matters submerged and apparently results in all fecal matter sooner or 

 37450°— 18 7 



