46 REVIEW — TROPICAL MEDICINE, ETC. 



Disinfe»;tion pormauganate, and from 200 c.c. to 500 c.c. of formaldehyde are required per 1000 cubic feet 

 —L-ontitKu.i of air space. The presence of added water is unnecessary. The chief point about this method 

 is the sliort exposure and the large quantity of gas evolved. It is also easily carried into 

 execution and does not require elaborate apparatus. 



Firth' draws attention to this method. The gas evolved consists of formaldehyde, 

 water-vapour, carbon dioxide, and traces of formic acid, and the reaction is apparently 

 expressed by the formula 



4 K Mn 0, + 3 H., CO + H, = 4 Mn (OH), + 2 K, CO^ + CO.. 



The proportion of the two substances which gives the best results and the driest residue, is 

 two parts of formalin to one part of permanganate. The method is effective, simple, rapid, 

 and, by virtue of the inexpensive apparatus required, preferable to the older and more 

 cumbersome methods. For a space of 2000 cubic feet, 285 grammes, or 10 oz., of the 

 permanganate and 570 cubic centimetres, or one pint, of formalin are required, the 

 reagents being mixed or added the one to the other in an ordinary galvanized-iron pail. 

 The crystals, which are better crushed, are put in first, and then the formalin is poured on 

 them. There is time for the operator to withdraw, and the period of disinfection should be 

 six hours. Heat and moisture are essential for efficient disinfection. From 60" F. to 70" F. is 

 a proper temperature, while it is well to render the air of the room moist in a dry country. 

 One has employed this method on several occasions in Khartoum, and it appears to be 

 efficient. The walls of the room to be disinfected are damped and the air sprayed with 

 water before the gas is evolved. Firth's paper, which deals generally with disinfection by 

 formaldehyde, contains much of interest, and he is inclined to urge the abandonment of 

 so-called room disinfection altogether and confine attention to the infected person, his 

 clothing and his bedding. The above method can be utilised for sterilising clothing in a 

 very simple manner. 



Eecent work on plague has drawn attention to disinfectants capable of killing fleas. 



SaigoP experimented with numerous chemicals. He found that petrol or benzine with 

 cyllin or phenyle (in equal quantities) made up to 1 in 300, i.e. 1 in 1600 of both, were 

 satisfactory. Actual contact with the fluid is necessary to kill the insects, though free use of 

 the emulsion will drive out of a house those that escape actual contact. Female fleas are 

 more resistant than the males. Both cyllin and phenyle emulsify petrol, but the former is 

 preferable owing to its greater germicidal powers. The emulsion, for the making of which 

 he gives directions, must be fresh. 



Somerville" found that cyllin 1 in 400 and phenyle 1 in 250, and Jeyes' fluid 1 in 250, 

 were efficient in five minutes, while a jelly of 80 per cent, petroleum with 20 per cent, 

 whale oil soap used in a 3 per cent, solution is said' to be the best contact insecticide known. 

 A 10 per cent, solution is absolutely certainly lethal for fleas. Hossack has done much 

 work on this subject. He confirms Saigol's work with petrol and phenyle, but not as 

 regards petrol and cyllin. This discrepancy was probably due to the difference in the 

 samples used. He concludes that " the ideal for plague purposes would be a cyllin with the 

 pulicidal power of the most potent samples of phenyle or phenyle with the germicidal 

 power of a cyllin." 



One may add a brief note on the disinfection of stools, and also of drain and water 

 pipes, as it is sometimes difficult to obtain reliable information on these latter points. 

 A good way of disinfecting cholera stools is to add together equal parts of fresh quicklime 

 and water. Then dilute the slake lime so formed with three times as much water as has 

 been previously used. Equal quantities of this mixture and cholera dejecta are thoroughly 

 stirred together and allowed to stand for an hour, when all the vibrios are killed. 



Fresh and good chlorinated lime in powder form, and in the proportion of two table- 

 spoonfuls to a pint of cholera dejecta, is effective in twenty minutes. Strong izal, 5 per cent., 

 or carbolic acid 1 in 10, with contact for two or three hours and thorough mixing, and a 

 sufficiency of the disinfectant (rough guide = complete covering of the stool), are measures 

 useful for enteric and dysenteric excreta. In typhoid bacilluria the urine may be diluted 

 with half its volume of 1 per cent, formalin. 



' Firth, R. H. (April, 1908), " Disinfection by Formaldehyde." Journal o} the Royal Army Medical Corps, 

 Vol. X., No. 4. 



"^ Saigol, R. D. (-July, 1907), "The Plea-killing Power of various Chemicals." Iiulian Medical Oazette, 

 p. 256, Vol. XLII. 



" Somerville, D. (August, 1907), " Disinfectants against Fleas." Indian Medical Gazette, p. 316, Vol. XLII., 

 No. 8. 



