By H. M. WILDER.
Editor of the American Journal of Pharmacy:
DEAR SIR,—I think that the following will be of use to some of your readers, particularly to those who have to depend on more or less muddy streams for their water supply, and who are not provided with a filtering apparatus, which, of course, is less expensive and obnoxious.
To clear muddy water I boil it with magnes. carbon. (1 tablespoonful to one or two gallons, according to its turbidity), and filter hot, magn. carbon. being much less soluble in boiling water (1:9000) than in cold (1:2500).
The only objection to the above is, a little dissolved carbon. of magnes. is not valid so long as the U. S. P. permits medicated waters to be prepared by means of it. As several salts and alkaloids are precipitated by it, it has been proposed to neutralize the water with a few drops of a diluted acid.
To eye-waters only distilled water ought to be taken, which it is not difficult to obtain in towns containing chemical manufactories.
An excellent substitute for distilled water has been recommended by the late Prof. F. F. Mayer, of New York, in Am. J. Pharm., xxxii, 172: Put a clear piece of ice in a filter, and let it melt.
Philadelphia, Sept. 24th, 1871.