REVIEW — TKOPICAL MEDICINE, ETC. 169 



An interesting account^ is given of the successful working of a sewage farm (septic tank Sewage- 

 system) in India. It served a leper asylum which contained fifty lepers ; the whole of the continu&l 

 effluent was used on a farm of about five-and-a-half acres, and the produce from the farm 

 amounted to thirty-six tons per acre. Plantains, guinea grass, lucerne grass and vegetables 

 were grown, but karbi and jowar (dura, millet) constituted the chief products. (In this 

 connection one may note that there is no evidence to show that the growing of fruit on 

 sewage farms is injurious to health, vide Public Health, December, 1906.) 



The gas given off from the septic tanks worked an engine, which actuated a small 

 centrifugal pump and daily lifted as much of the fluid to the filters as was required. The 

 fodder crops were used for the feeding of bullocks, and the profits wholly maintained the 

 fifty lepers. 



When the effluent, as in this case, is chiefly applied to the land, one purification only 

 of the sewage appears necessary, and nearly the whole of the effluent used on the farm 

 came directly from the septic tank. Unfortunately, the cost of establishment and of 

 maintenance is not mentioned. 



Caldwell- contrasts artificial and natural disijosal of sewage. He points out that the 

 three principal methods now employed are the chemical, the biological and the natural — 

 the first two being classed under the term " artificial." He speaks strongly in favour of the 

 natural methods, especially when shallow trenches are used as in some parts of India, 

 saying :— 



" The contents of latrine buckets and night-stools are collected by the sweeper, dumped into a 

 Crowley's filth cart, and carried to the grass farm, where the contents of each cart, averaging sixty gallons, 

 are emptied into a trench 9 inches deep 5 feet wide and 16 feet long. The trench is then filled in, and in the 

 course of a few days all trace of oiiensive matter has, under the influence of the soil organisms, absolutely 

 disappeared. It is an interesting fact, as bearing on the presence of the necessary organisms in the superficial 

 layers of the soil only, that a horse, galloped over ground newly operated on, could not make an impression in the 

 soil deeper than two inches, whereas if refuse was buried at a greater depth horses sank almost knee-deep in the 

 soil when taken over it. I have myself examined samples of soil carefully by ordinary bacteoriological methods, 

 and I have never succeeded in detecting the presence of coliform bodies later than the fifth day after burial, but 

 I must at the same time make it absolutely clear that I have no intention to dogmatise concerning a matter 

 which certainly needs further investigation." 



This question will be discussed more fully under " Sanitary Notes " (Third Eeport). 



Kenwood, s in criticising a paper by Starkey on the economical disposal of sewage in 

 small rural communities, draws attention to the danger of sewage becoming over-septieised if 

 left too long in a septic tank. The result is a deposition of colloid matter which renders the 

 working of the tank very ineffective. 



Phelps and Winslow* advocate the use of methylene blue in testing sewage effluents, 

 i.e. as regards their stability with reference to putrefaction. They state that it directly 

 measures the quality of most importance in a sewage effluent, i.e. its freedom from the 

 tendency to putrefactive change, and that it registers this with a greater delicacy than any 

 method with which they are acquainted. Moreover, it is so simple in technique as to be 

 peculiarly adapted to sewage works where neither a laboratory nor an expert chemist are 

 available. Their description of it is as follows : — 



A small portion of an aqueous solution of the dye (in our experiments 1 c.c. of a 0-1 per cent, solution) is 

 added to the effluent in a glass stoppered bottle (250 c.c. capacity in our work), and the sample is then incubated 

 either at 20° C. or at 37° C. The blue colour of the solution remains practically unchanged during the period of 

 observation until the available oxygen contamed in it is used up and putrefactive conditions arise. At this point 

 the dye is reduced and decolorised. The time required for such decolorisation is a quantitative measure of the 

 degree of putrescibility of the sample and the retention of the colour for a period of one week or more, at 20° C, 

 or of four days at 37° C, may be taken as an indicator of its stability. 



Clemesha,'^ '^ in two papers considers the value of chlorinated lime for sterilising septic 

 tank effluents in India, in order to prevent the pollution of rivers, and concludes : — 



(i.) That 5 grains per gallon of chloride of lime is ample to sterilise a bad effluent, and that this amount 

 leaves a good margin for erratic workmg. 



' " A Successful Septic Tank and Sewage Farm : Notes from India." Lancet, June 4th, 1904, Vol. I. 



" Caldwell, R. (March, 1908), "Artificial and Natural Sewage Disposal Contrasted." Journal of tlu: Royal 

 Institute of Public Health, Vol. XVI.' 



» Kenwood, H. R. (August 17th, 19071, Jleeting of Brit. Med. Assoc. Sec. of State Medicine. Lancet, Vol.11. 



♦ Phelps, E. B., and Winslow, C. E. A. (May, 1907), " Use of Methylene Blue in Testing Sewage Effluents." 

 Journal of Infectious Diseases, Suppl. 3. 



» Clemesha, W. W. (March, 1906), " Experiments for SterilisiBg Septic Tank Effluent." Indian Medical 

 Gazette, Vol. XLI. 



« Clemesha, W. W. (October, 1906), " Further Note on the Use of Chloride of Lime to Sterilise Septic Tank 

 Effluents." Ibid. 



