_Our Correspondent_ C. E. F. (p. 373.) _is informed_--1. _That both the solutions of the muriate salts and the nitrate of silver may be used in the manner he proposes; but a portion of sugar of milk, mannite, or grape sugar, as has been previously recommended, much accelerates the process._ 2. _The positives should be printed about one-third deeper than is required, and they should remain in the hypo. bath until the mottled appearance is removed, which is visible when held up against the light and they are looked through: at first the positive often assumes a very unpleasant red colour; this gradually disappears by longer immersion, when the proofs may be removed at the point of tint required, remembering that they become rather darker when dry, especially if ironed, and which is generally desirable, especially if the print is rather pale._ 3. _The sel d'or does not seem to have the destructive effect which the chloride of gold has, and if the chemicals are entirely removed, in all probability they are quite permanent. Those which we have seen printed several months since appear to have suffered no change. Pictures produced by the ammonio-nitrate are most uncertain. There are few who have not had the mortification to see some of their best productions fade and disappear. A learned professor, about eighteen months since, sent us a picture so printed "as something to work up to;" a few yellowish stains are now all that remains on the paper._ * * * * * "NOTES AND QUERIES," Vols. i. _to_ vii., _price Three Guineas and a Half.--Copies are being made up and may be had by order._ "NOTES AND QUERIES" _is published at noon on Friday, so that the Country Booksellers may receive Copies in that night's parcels, and deliver them to their Subscribers on the Saturday._ * * * * * EDITED FOR THE SYNDICS OF THE CAMBRIDGE UNIVERSITY PRESS. This Day, 3 vols. 8vo., 42_s._ GROTIUS DE JURE BELLI ET PACIS; Accompanied by and Abridged Translation of the Text. By W. WHEWELL, D.D., Master of Trinity College, and Professor of Moral Philosophy in the University. With the Notes of the Author, Barbeyrac and others. Also, 8vo., 14_s._ GROTIUS ON THE RIGHTS OF WAR AND PEACE. An Abridged Translation. By DR. WHEWELL. London: J. W. PARKER & SON, West Strand. * * * * * This Day, small octavo, 9_s._ 6_d._ PHRASEOLOGICAL AND EXPLANATORY NOTES ON THE HEBREW TEXT OF THE BOOK OF GENESIS. By THEODORE PRESTON, M.A. Fellow of Trinity College, Cambridge. London JOHN W. PARKER & SON. Cambridge J. DEIGHTON. * * * * * This Day, Octavo, 3_s._ 6_d._ CICERO PRO MILONE. With a Translation of Asconius' Introduction, Marginal Analysis, and English Notes. Edited for the Syndics of the Cambridge University Press. By the REV. J. S. PURTON, M.A., President and Tutor of St. Catharine's Hall. London: JOHN W. PARKER & SON, West Strand.