132 



Baoot (A. W.) & Lloyd (L). Destruction of Nits of the Clothes Louse 

 by Solutions of Cresol-soap Emulsion and Lysol. — Brit. Med. Jl., 

 London, no. 2991, 27th April 1918, pp. 479-480. 



A precautionary measure frequently adopted at baths and wash- 

 houses where the clothes of infected troops are treated to rid them 

 of lice consists in steeping infected garments in a vat containing 

 solutions of cresol-soap emulsion. Experiments to determine the 

 strength of the solution and the period of immersion necessary to 

 destroy the eggs of Pediculus hnm,anus have established the fact that 

 steeping for 20 minutes in a 2 per cent, solution of either lysol or 

 cresol soap is quite effective, provided that the temperature is not below 

 50° F. [10° C.]. It must be noted however that hot water or dry 

 heat at 131° F. [55° C] destroys both eggs and active lice within 30 

 minutes, even when protected by a covering of khaki cloth, while if 

 the temperature is raised to 140" F. [60° C] 15 minutes suffice. Hence, 

 if the garments are subjected to the above temperatures and periods 

 during washing or drying, the use of chemical solutions is unnecessary, 

 and, conversely, if chemical solutions are used, temperatures so high 

 as the above for washing or drying are equally superfluous. 



Further experiments are needed to prove whether solutions of 

 cresol-soap emulsion and lysol degenerate in their effectiveness 

 against the eggs of lice in the same way as they do against bacteria, 

 owing to the presence of organic matter with which they become 

 charged during use. 



HoLBOROw (A. G.). The RestraiMing Influence of Cyanide upon 

 Oxidation in Arsenical Dips. — RJwdesia Agric. Jl., Salisbury, xiv, 

 no. 6, December 1917, pp. 733-737. 



This paper records research work undertaken with the object of 

 preventing oxidation of arsenical dipping solutions, in the course of 

 which sodium arsenite is changed into sodium arsenate, a substance 

 having only about one-half the tick-killing power of the arsenite. 

 One very practical method of preventing oxidation is to agitate the 

 solution constantly by passing cattle through it at regular and fre- 

 quent intervals. The cause of the oxidation however is not explained. 

 It is evidently not spontaneous, for solutions of arsenic can be kept 

 in the laboratory for over a year without any material change. It 

 has been stated that micro-organisms play an important part in the 

 process of oxidation, but the results of the author's experiments, 

 given in a series of tables, do not bear out this view. Various disin- 

 fectants were tried, including formalin, corrosive sublimate, carbolic 

 acid and boric acid, but all failed to arrest the oxidation. Other 

 methods tried for arresting the action of possible micro-organisms 

 include sterilisation in an autoclave, boiling for half an hour, and pass- 

 ing the original dipping fluid through a bacterial filter. It was found 

 that while cyanide does not completely arrest oxidation, the addition 

 of as little as 0"005 per cent, of potassium cyanide permitted an 

 increase of oxidation of only 13 per cent., whereas the untreated dip 

 showed an increase of 83 per cent, of oxidation in 11 days. 



