86 METHODS OF STERILISATION 



around the stitches, a circumstance sufficient to account for the bad repute in 

 which wort- and beer-droppings are held. Disinfection experiments have, 

 however, shown that these germs can be killed by exposure to the action 

 assisted by careful brushing of a chloride of lime solution containing i per cent, 

 of active chlorine. As good commercial chloride of lime yields 30-35 per cent, 

 of chlorine, the solution may be prepared for use by mixing 3-3 \ kilos. (6.6-7.7 

 Ibs.) of the chloride with i hectolitre (22 gallons) of water i.e. about 5 oz. per 

 gallon stirring the mixture up frequently, and, after settling, pouring off' the 

 clear liquid from the (useless) sediment. According to R. Koch, 0.2 percent, 

 chlorine water will kill the spores of B. anthracis within an hour. Exhaustive 

 experiments conducted chiefly from a medico-hygienic point of view on the 

 anti-bacterial properties of chlorine and bromine haye been carried out by 

 BERNHARD FISCHER and B. PROSKAUER (I.). 



Among the inorganic acids, hydrofluoric acid and its alkali salts have proved 

 to be particularly poisonous to bacteria. In the last few years this substance 

 has, by the labours of Effront, been utilised in distilleries ; on this head more 

 detailed reports will be given in a later section. 



Boric acid, either per se or in the form of borax, is occasionally in despite 

 of prohibitory regulations used for preserving food-stuff's (e.g. milk). A per- 

 missible and useful application of this substance may be made in the preparation 

 of starch paste by employing an aqueous solution of borax as a substitute for 

 water. Paste prepared in this way can be recommended, for instance, for 

 affixing the labels on wine bottles kept in store, the occurrence of the uncleanly 

 formation of mould, otherwise intervening, being thereby prevented. 



The effect of ozone and hydrogen peroxide on bacteria is due to a common 

 cause, viz., the decomposing power of the oxygen liberated. Accoiding to the 

 determinations made by H. SONNTAG (I.), ozone has only a weak germicidal 

 power, but other experimenters, e.g. OBERDORFFER (I.) and WYSSOKOWIT.SCH (I.), 

 obtained somewhat more favourable results. According to the researches of 

 OHLMULLER (I.), this gas acts more powerfully when it is passed, along with 

 oxygen, through the culture. When the volume of the liquid amounted to 

 500 c.c. an ozone-content of 90 m.grms. of O 3 per 100 c.c. of the gas was requisite 

 in order to kill the germs of the spores of anthrax bacillus present. According 

 to the researches of CHRISTMAS (L), the germicide power of ozone sinks to ntZ 

 when its amount falls below 0.05 per cent, by volume ; so that no effect can be 

 anticipated from the much lower proportion (i-io m.grms. per 100 litres) of 

 ozone present in the atmosphere. With regard to the purification of river water 

 intended for drinking purposes by the aid of ozone, prepared artificially on 

 a large scale, an exhaustive report has been drawn up by E. VAN ERMENGEM (I.). 



Owing to the great expense entailed, the utilisation of the anti-bacterial 

 power of hydrogen peroxide in the service of the fermentation industry is as 

 yet impracticable. The invention of a less expensive method of production 

 would, however, ensure it an extensive sphere of operation, since this bacterium 

 poison offers the advantage that during its action it is resolved into water and 

 oxygen. When the latter has killed the organism, nothing is left of the anti- 

 septic but harmless water. Great advantage might be derived from this property 

 in connection with the manufacture of conserves ; but hitherto its value does 

 not seem to have been sufficiently appreciated. A few experiments have, how- 

 ever, 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 O Z 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 alteration in 



