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ANSWERS TO CORRESPONDENTS.

W. O. R., Mo., Mr. R. writes—"Will you have the kindness to inform me of any new process for preparing phosphate of iron. I make the request more particularly to obtain a process by one Mr. Routh, who I understand has a new process."

The preparation referred to by Mr. R., was read before the London Medical Society, January 11, 1851, by Dr. Routh, at which time he exhibited specimens of phosphate of iron made by dissolving the ordinary phosphate in meta-phosphoric acid, and by then evaporating to degrees. It has been found that this form of iron is exceedingly useful in cases where iron is desired.

W. B. N., Mexico—Mr. N. says—"Will some of your subscribers give, through your Journal, a practical and first-rate process for producing Calotypes?"

We hope some of our "subscribers" will furnish the same.

H. B. T., Ohio.—Mr. T. says—"Will you give a ready and easy method of detecting chlorine? I find in a former number of your valuable Journal, that you have been making experiments with this gas. I have had remarkable success with this gas, although not a practical Daguerreotypist."

Mr. J. will find 'this gas' is readily distinguished from other gases by its color, odor, and bleaching properties. Probably the most simple method of detecting free chloride is to hold a rod dipped in aqua ammonia over it, when white fumes will be formed.

Will Mr. J. have the kindness to forward to us his experiments—we would like much to lay them before our readers.