EUEAL ECONOMICS. 



89 



all three plants have operated succes.sfuHy and have produced effluents of satis- 

 factory character. 



A summary of the results of experiments on the purification of creamery- 

 refuse and their application, H. R. Ceohuest and A. D. Weston {Engin. and 

 Contract., 4-^f {1915}, No. 1, pp. 7-9). — This article summarizes data and con- 

 clu.sions obtained in experiment stations in this country and in Europe on the 

 fiubject of creamery refuse disposal. 



It is stated that the wastes produced in the dairy industry consist chiefly of 

 dilute solutions of milk in which are particles of butter, fat, and ca.sein which 

 come from the washing of the products, utensils, and floors. The waste is very 

 susceptible to bacterial action, quickly becomes acid, containing approximately 

 1,000 parts per million acidity, and gives rise to very disagi-eeable odors due to 

 the production of butyric acid. Because of the high oxygen demand it creates a 

 nuisance when discharged into small streams by quickly using up the available 

 oxygen, after which putrefaction begins. 



From the available data the following methods of purification are suggested 

 as the result of exi^eriments : " Where the volume of the waste is comparatively 

 small and suitable land is available it may be disposed of by irrigation at rates 

 varying from 20,000 to 2,000 gal. per acre per day. If suitable land is not avail- 

 able one of the following biological methods is suggested: Sedimentation in 

 septic tanks for from two to ten days and, if diluting water in suflicient volume 

 is at hand, disposal by dilution ; sedimentation in a septic tank for from two to 

 ten days, followed by filtration through sand at rates not to exceed 25,000 gal. 

 per acre per day (where sand treatment is employed it is recommended that the 

 acidity be i-educed by the addition of lime so that bacterial action will not be 

 retarded) ; sedimentation in septic tanks for from two to ten days, followed by 

 treatment in primary contact beds, and if necessary by secondary contact beds 

 <ir trickling filters (trickling filter treatment following sedimentation is not 

 recommended because of the dispersion of odors in applying the liquid after 

 sedimentation to the surface of the filter). . . . 



" It is felt that any of the above methods of treatment will produce an efflu- 

 ent which will not give rise to a nuisance when discharged into a small stream 

 or brook." 



ETJUAL ECONOMICS. 



Farming and food supplies in time of war, R. H. Rew (Jour. Bd. Agr. 

 {LondoM, 22 (1915), Ko. 6, pp. 50It-520 ; Nature [London], 96 {1915), No. 2399, 

 pp. 216-220; Science, n. ser., ^2 {1915), No. 108Jf, pp. 475-486).— This paper 

 treats of the relation of the total consumption to the home production and the 

 influence of war on this relationship. The following table indicates the sources 

 of the food supply of the United Kingdom : 



Sources of food stuffs consumed in the United Kingdom, 1910-1914 



Including margarin. 



* Including cream. 



