Iowa City, Iowa, July 20, 1906.
To the Editor
—A note in The Journal, July 14, in the department of Miscellany, states that in using the potassium permanganate method of liberating formaldehyd gas the amounts used are 3% ounces of potassium permanganate and 1 pint of 40 per cent, solution of formaldehyd to every 1.000 cubic feet of air space to be disinfected. During the past two years I have experimented a great deal with this and other methods of generating formaldehyd gas in the Iowa State Board of Health bacteriologic laboratory and in buildings of all kinds to test thoroughly the various methods. I consider the potassium permanganate method of liberating gas as the best. Realizing that it will no doubt be adopted more and more by the physicians of the country, I can not forbear making a correction in the article above referred to.It is impossible to