no METHODS OF STERILISATION. 



and, after settling, pouring off the clear liquid from the (useless) 

 sediment. According to R. Koch, 0.2 per cent, chlorine water 

 Avill 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 have 

 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 occasion- 

 ally in despite of prohibitory regulations used for preserving 

 food stuffs (e.g. milk). A permissible 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. According to the determinations made by H. SONNTAG 

 (I.), ozone has only a weak germicidal power, but other experi- 

 menters, e.g. OBERDORFFER (I.) and WYSSOKOWITSCH (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 

 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 (I.), the germicide power of ozone sinks 

 to nil 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 antiseptic but harmless water. Great advantage might be 

 derived from this property in connection with the manufacture: 



