84 METHODS OF STERILISATION 



warmth is seconded by suitable antiseptics, substances which we must first 

 consider before noticing the combined process of sterilisation to which we are 

 gradually leading up. 



79. Mineral Antiseptics. 



The substances exerting a toxic action on micro-organisms are still often 

 divided into two groups : those serving to annihilate the pathogenic bacteria being 

 termed disinfectants; whilst the substances capable of retarding fermentation 

 and putrefaction are denominated antiseptics. There are, however, no good 

 grounds for this distinction, since, as we know, there are bacteria capable of 

 originating both disease and fermentation. 



Very exhaustive researches on the efficacy of the vai-ious antiseptics are 

 available. Those of R. KOCH (I.) were undertaken in the interest of medical 

 hygiene. As in the case of other agencies inimical to bacteria, so is it in the case 

 of toxic substances : the destruction of the life of vegetative forms of growth is 

 relatively the easiest to effect ; stronger means being necessary to prevent the 

 germination of the endospores, and the most powerful influences of all to kill 

 these latter. 



The strongest antiseptic is corrosive sublimate, or mercuric chloride, HgCl, ; 

 but, unfortunately, this substance cannot, for hygienic reasons, be employed in 

 the fermentation industiy. In the laboratory, however, the fermentation 

 physiologist always keeps a stock of this reagent for disinfecting (inter alia) the 

 bell glasses used for storing fresh plate cultures. A sufficient quantity is also 

 put in vessels containing cultures that are no longer needed, but which should 

 not be placed in the hands of the cleaner until they have been killed. Again, in 

 the laboratory of the chemist in large works a solution of sublimate should always 

 be kept, along with materials for bandages, as being the first remedy to apply 

 when the workmen are injured or wounded. In washing wounds with this 

 solution, one should always be mindful of the fact that the first treatment has a 

 preponderating influence in the restoration of health. The strength of solution 

 employed, both in the laboratory and for this Samaritan service, is one gram 

 of HgCl, per litre of distilled water. Calcareous well-water must not ^be used, 

 and the author would recommend any chemist who cannot afford to purchase 

 distilled water to prepare his stock of sublimate solution in rainy weather, using 

 pure rain water for that purpose. Like most of the salts of mercury, sublimate 

 forms insoluble compounds with albuminoids (e.g. in the blood), and has then no 

 longer any effect on bacteria. This reaction is prevented by adding 5 grams of 

 sodium chloride per litre of solution, since this salt forms with the mercuric 

 chloride a double salt soluble in water. According to the researches of R. Koch, 

 the spores of Bacillus anthracis perish in an hour when immersed in this solution. 

 For the prevention of their germination the presence of i part of sublimate in 

 300,000 parts of water suffices. 



The earliest disinfectant employed was sulphurous acid, the use of which for 

 sulphuring wine casks has been handed down from remote ages. In this process, 

 so-called sulphur threads are ignited and placed in the cask, being prevented from 

 falling by the bung. These sulphur threads are strips of linen about the breadth 

 of the finger, steeped in melted sulphur. The germicide properties of gaseous 

 sulphurous acid (sulphur dioxide) were examined by G. WoLFFHtiGEL (I.) ; and 

 G. LINOSSIER (I.) endeavoured to express in figures the relation between the 

 percentage content of a solution of this dioxide and the length of exposure 

 necessary to kill various germs. His experiments were not conducted with 

 bacteria, but with Eumycetes ; they are, nevertheless, given in the following 

 Table : 



