1. What paper does he use for positives, and what for negatives?

2. Is it not better to dissolve the silver and iodide of potassium in three

ounces of water each instead of one (see "N. & Q.," Vol. vii., pp. 151.

277.)?

3. Is spring water fit for washing the iodized paper; if it contains either

sulphate or bicarbonate of lime or muriate of soda?