The Action of Carbon Filters.

Abstract

If one filters 100 cc. of a 1% solution of bichloride of mercury through a filter made of 5 gm. of finely divided activated carbon there is no mercury in the filtrate. If one filters through such a filter 100 cc. of a 1% solution of ferric chloride there is no ferric chloride in the filtrate but 92.5% of the iron is in the filtrate in the form of ferrous chloride. The carbon in both cases has reduced the perchlorides; in the case of mercury the mercurous chloride is insoluble and remains in the filter carbon; in the case of iron the ferrous chloride is soluble and passes through the filter.

Solutions of the toxins of the tetanus, diphtheria and Botulinus bacilli respectively were filtered through carbon and in each case the filtrate, when injected into guinea pigs in doses corresponding to 5000 M.L.D. were found to be innocuous. In each case some of the carbon through which the toxins had been passed was injected into guinea pigs.

In the case of the diphtheria toxin-carbon the animal showed no symptoms. In the case of the tetanus and botulinus toxin the animals died with the lesions and symptoms characteristic of the respective toxin.

The tetanus and botulinus toxins are formed under anaerobic conditions and are “immune” to reduction; they are adsorbed by the carbon but not destroyed by its reducing action.

The diphtheria toxin is formed under aerobic conditions and is both adsorbed and rendered innocuous or destroyed by the reducing action of the carbon.

If 50 cc. of a 1/2% solution of strychnine sulphate is filtered through such a carbon filter the filtrate is free of strychnine to the taste and gives no test for alkaloid, nor does it affect the frog.