Abstract
Summary
A toxic factor present in our distilled water found lethal to Paramecium was analyzed. The results show that it is not related to pH, can be duplicated by 5 metallic salts at specific concentrations (M) as follows: cupric chloride, 10-6; cupric sulfate and cupric nitrate, 20-6; zinc acetate, 10-4; lead acetate, 25-4; and can be neutralized by 0.02 M CaCl2. Calcium chloride is likewise capable of neutralizing cupric chloride and lead acetate, but not cupric sulfate, cupric nitrate or zinc acetate. These results coupled with the demonstration that the presence of SO4 −−ions actually destroys the neutralizing power of calcium indicate strongly that the toxic factor under consideration could possibly be copper chloride and/or lead chloride, not likely sulfate or nitrate of copper or zinc acetate. Generally the results also confirm the protective action of Ca++ against ionic imbalance or unknown impurities in water as reported by other workers. Because of the demonstrated sensitivity of Paramecium to metallic ions we commend its use as an indicator for low-level toxicity due to such ions in solutions including distilled water not made and stored in pyrex glass.
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