1915 Experimental Observations on the Antiseptic Action of Hypochlorous Acid and Its Application to Wound Treatment

The British Medical Journal
July 24, 1915

The primary object of the following investigation was to find an antiseptic which could be applied as a first dressing in the field to prevent sepsis. The ideal antiseptic for the type of infection which occurs in wounds received in the field must possess the power of rapidly destroying spores as well as ordinary bacterial forms. There are two chief laboratory methods of investigating the action of antiseptics:

1. By testing their action in killing or preventing the growth of organisms on artificial culture media.
2. By testing their action in sterilizing infected organic matter.

In our investigation we employed both methods, but especially the latter, as the conditions there resemble more closely those occurring in infected wounds containing much necrotic tissue or other organic matter. 

The result of preliminary observations was to direct attention to the hypochlorites. It has been accepted, especially by those working at disinfectants for public health purposes, that the hypochlorites are among the most potent germicides. Rideal, using carbolic acid as a standard, expresses the germicidal power of hypochlorites as follows: Carbolic acid, 100; hypochlorites, 14,600 to 22,000.

The hypochlorites, used mainly in the form of bleaching powder, have been largely employed for sterilizing water supplies, but their use in general surgery as antiseptics has been very limited. It is an interesting fact that as far back as 1846 Semmelweis stamped out an epidemic of puerperal fever in Vienna by the use of bleaching powder.

Solutions of alkai hypochlorites, for example "Eau de Javelle," have been used with success in surgical practice. The fundamental practical difficulty in the use of hypochlorites is that in solution they rapidly lose their strength by decomposition. In the case of Eau de Javelle this difficulty has been overcome by making a strongly alkaline solution; but this constitutes a new difficulty, in that such a highly alkaline solution cannot be applied to the tissues unless greatly diluted.

In our observations on the hypochlorites we found that hypochlorous acid is a more potent germicide than its salts, and we have accordingly-devised a method in which the free acid is employed as the antiseptic agent. The acid may be used as a gas or as a solution in water.

Hypochlorous Acid
For use as an antiseptic the gas is most conveniently prepared by the action of boric acid on bleaching powder in the presence of small quantity of water. The solution is obtained when the same action occurs in the presence of a large quantity of water.

For convenience we have given the name "Eupad" to a powder consisting of equal weights of finely ground bleaching powder and powdered boric acid intimately mixed; while the solution of free hypochlorous acid prepared in this way we have named "Eusol."

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