To the Editor:
—In The Journal, Sept. 19, 1914, p. 1025. I presented the formula of a mixture in which potassium permanganate was replaced by sodium dichromate.We have found that the formaldehyd solution shipped in combination with the sulphuric acid, when subjected to the extremely low temperatures of winter, is not sufficiently stable for Northern climates. By adding 1½ fluidounces of glycerin to this formula, we have secured a stable solution that will bear moderately low temperatures without loss of efficiency and without polymerization. We are now using the following formula:We have also learned that when the acidulated solution has shown a tendency to become cloudy or milky because of the low temperatures, it may be clarified and made potent by gently warming for a long period of time.