S4 BACTERIOLOGY. 



in a room in which the gas was generated by burning sulphur in 

 the ordinary way for disinfecting a room. To test chemicals which 

 might be recommended for disinfecting vans and railway carriages, 

 spores were laid on boards, which were then washed or sprayed, and 

 the spores then transferred to the nutrient gelatine. 



Sternberg has also made an elaborate series of experiments with 

 regard to the action of germicides. In this case cultivations of 

 well-known pathogenic organisms in liqiiid media were employed. 

 The supposed germicide was added to the liquid cultivation, and 

 after two hours a fresh flask of sterilised culture was inoculated from 

 the disinfected cultivation, and placed in the incubator. In twenty- 

 four to forty-eight hour.s, if the chemical proved inefficient, there 

 was evidence of a growth of bacteria. Blyth has investigated the 

 disinfection of cultivations of Bacterium termo, of sewage, and 

 typhoid excreta, and, in conjunction with EHein, the effect of well- 

 known disinfectant materials on anthrax spores. Miquel, Laws, 

 and others have also contributed to our knowledge of the . effect 

 of antiseptics and disinfectants upon micro-organisms. In spite of 

 all that has been done there is room for many workers ; a great 

 deal of ground must be gone over again to rectify discrepancies,, 

 examine conflicting results, and thus determine what observations 

 may be relied upon for practical application. 



This may be illustrated by referring in detail to some experiments 

 made with corrosive sublimate. Koch investigated a long Hst of 

 chemical reagents, and according to these experiments the salts of 

 mercury, and the chloride especially, proved most valuable. Where 

 heat is not admissible, these compounds were therefore highly 

 recommended, though their poisonous nature is a drawback to their 

 indiscriminate use. Koch stated that for disinfecting a ship's bilge, 

 where a 5 per cent, solution of carbohc acid must be left forty-eight 

 hours, a 1 in 1000 solution of mercuric chloride would only require 

 a few minutes. 



But there was good reason for doubting the efficacy of very dilute 

 solutions; for, though according to Koch's experiments anthrax 

 spores subjected to a 1 in 20,000 solution of mercuric chloride for 

 ten minutes,- and then washed in alcohol, gave no growth in nutrient 

 gelatine, silk threads exposed for ten minutes to a 1 in 20,000 

 solution, or even 1 in 10,000, still proved fatal to mice. 



Herroun cultivated ordinary septic bacteria in albuminous 

 filtrates, containing . 1 in 2000, and concluded that the value of 

 mercuric chloride as an antiseptic was much over-rated. It is pre- 

 cipitated by albumins though, as Lister has shown, the precipitate 



