MINEKAL ANTISEPTICS. in 



of conserves ; but hitherto its value does not seem to have been 

 sufficiently appreciated. A few experiments have, however, been 

 made with it in connection with the freeing of drinking water 

 from germs. In partial improvement on the results reported by 

 Van Tromp, it has been proved by ALTEHOEFER (I.) and P. SCHILOW 

 (I.) that an addition of i part per mil of H 2 2 to drinking water 

 will, within twenty-four hours, be fatal to the common (innocuous) 

 water bacteria, the microbes usually present in conduit waters, 

 and the organisms which produce cholera and typhus. No altera- 

 tion in flavour results from this application; and an injurious 

 influence on health is the less likely, since the peroxide is quickly 

 decomposed. A reduction of the dose below i per mil would 

 naturally interfere with the efficiency of the reaction, a circum- 

 stance which explains the unfavourable results obtained by other 

 experimenters, reported by A. SCHROHE (I.). A proposal, worthy 

 of being followed up, has been made by A. GOTTSTEIN (II.). 

 A sample of water containing 1000 bacteria per i c.c. was found 

 to. evolve bubbles of gas at its upper edges fifteen minutes after 

 the addition of H 2 2 , the gas being oxygen liberated from the 

 peroxide by the activity of the microbes. Since the extent of 

 this evolution of gas fluctuates in accordance with the number of 

 living bacteria present, this behaviour might perhaps be utilised 

 in arranging a simple method for controlling the efficiency of 

 water filters at frequent intervals. No appliances beyond a stock 

 of hydrogen peroxide and sterilised test-glasses would be required. 

 Of course, this crude method neither could nor should be used to 

 replace the examination of the efficiency of the filter by bacterio- 

 logical tests, but is intended for the sole purpose of enabling the 

 engineer in charge to convince himself, every quarter of an hour 

 (or at other selected intervals), that the filtrate has fewer bacteria 

 than the unfiltered water. According to the critical researches of 

 HUGO LASER (I.), the Gottstein method is not sufficiently reliable. 

 Milk of lime is, when fresh, a fairly good disinfectant, but 

 loses its disinfecting property as soon as the calcium hydroxide 

 becomes converted into carbonate, the latter being innocuous 

 towards many organisms, and even favourable to others (especially 

 the acid-forming microbes). In the absence of other disinfectants 

 this liquid may be successfully used. According to the researches 

 of E. PFUHL (I.), it is sufficient to add two volumes thereof, and 

 leave them to react for an hour, to ensure the death of the typhus 

 bacilli and cholera bacteria in liquid faecal matter. L. STEUBER (I.) 

 has made several experiments as to the influence of milk of lime 

 on yeast-cells, and on its suitability for disinfecting brickwork in 

 the brewery. 



