ON THE DETERMINATION OF THE TOXICITY OF NEOARSPHENAMINE I. THE INCREASE IN TOXICITY ON EXPOSURE TO AIR

¹ Laboratory of Hygiene, Department of Pensions and National Health, Ottawa, Canada

1. Four per cent solutions of neoarsphenamine, standing exposed to air for twenty minutes, increase in toxicity as much as 56 per cent, calculated on the basis of solutions five minutes old. Evidence is presented that the increase in toxicity of solutions caused by their preparation and fifteen minutes exposure to air is about 107 per cent, calculated on the basis of protected solutions.

2. These increases in toxicity of neoarsphenamine solutions can be prevented by preparing and keeping them under a layer of white mineral oil as described in this paper. Neoarsphenamine solutions thus protected show no increase in toxicity after standing under oil for one hour, and there is some evidence that no increase in toxicity occurs in two and a half hours.

3. There is a slight decrease in the toxicity of neoarsphenamine solutions kept under oil. This decrease remains constant and is insignificant when compared to large increases shown by unprotected solutions.

4. The alterations in the toxicity of unprotected solutions makes it impossible to obtain accurate or consistent results if they are used in toxicity tests. Protected solutions yield consistent and reliable results.

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