THE EFFECTS OF CERTAIN ANTISEPTICS 171 



when in the breaking up of ozone the free third atom of the 

 ozone molecule is seeking to unite with another similar atom ; 

 secondly, when peroxide of hydrogen is broken up into water 

 and an oxygen atom is thereby liberated. In commerce the 

 activity of "Sanitas" compounds is due to the formation of 

 ozone by the slow oxidation of the resin, camphor, and thymol 

 they contain. 



Perchloride of Mercury. Of all the salts of the heavy metals 

 this has been most widely employed, and must be regarded as 

 one of the most powerful and useful of known antiseptics. In 

 testing its action on anthrax spores there is no doubt that in the 

 earlier results its potency was overrated from a neglect of the 

 fact already alluded to, that in the spore-case an albuminate of 

 mercury was formed which prevented the contained protoplasm 

 from developing, while not depriving it of life. It has been 

 found, however, that this salt in a strength of 1-100 will kill the 

 spores in twenty minutes, although an hour's exposure to 1-1000 

 has no effect. The best results are obtained by the addition to 

 the corrosive sublimate solution of '5 per cent, of sulphuric acid 

 or hydrochloric acid ; the spores will then be killed by a seventy- 

 minute exposure to a 1-200 solution. When, however, organisms 

 in the vegetative condition are being dealt with, much weaker 

 solutions are sufficient; thus anthrax bacilli in blood will be 

 killed in a few minutes by 1-2000, in bouillon by 1-40,000, and 

 in water by 1-500,000. Plague bacilli are killed by one to two 

 minutes' exposure to 1-3000. Generally speaking, it may be said 

 that a 1-2000 solution must be used for the practically instan- 

 taneous killing of vegetative organisms. 



Perchloride of mercury is one of the substances which have 

 been used for disinfecting rooms by distributing it from a spray 

 producer, of which the Equifex may be taken as a type. With 

 such a machine it is calculated that 1 oz. of perchloride of 

 mercury used in a solution of 1-1000 will probably disinfect 3000 

 square feet of surface. Such a procedure has been extensively 

 used in the disinfection of plague houses, but the use of a stronger 

 solution (1-500 acidulated) is probably preferable. 



Formalin as a commercial article is a 40 per cent, solution of 

 formaldehyde in water. This is a substance which of late years 

 has come much into vogue, and it is undoubtedly a valuable 

 antiseptic. A disadvantage, however, to its use is that, when 

 diluted and exposed to air, amongst other changes which it 

 undergoes it may be transformed, under little understood 

 conditions, into trioxymethylene and paraformaldehyde, these 

 being polymers of formaldehyde. The bactericidal values of these 



