BOOKS WANTED.--_We believe that gentlemen in want of particular books, either by way of loan or purchase, would find great facilities in obtaining them if their names and addresses were published, so that parties having the books might communicate directly with those who want them. Acting on this belief, we shall take advantage of the recent alteration in the law respecting advertisements, and in future, where our Correspondents desire to avail themselves of this new arrangement, shall insert their names and addresses_--_unless specially requested not to do so_.
J. N. RADCLIFFE. _We shall be glad to receive the Legendary Lore mentioned by our Correspondent._
REV. H. G. _Your letter has been forwarded to_ A. F. B. (Diss).
S. Z. Z. S. _We have a letter waiting for this Correspondent; how can we forward it?_
C. E. F. _Warm water and a few small shot will thoroughly cleanse the bottles in which collodion has been kept._
AN AMATEUR EXPERIMENTALIST. _Formerly the pint used in the compounding of medicines, chemicals, &c. consisted of sixteen fluid ounces, weighing one pound Avoirdupois weight. Now the imperial pint of twenty ounces is in general use. The Troy and apothecaries' ounce are the same, and contain forty grains more than the Avoirdupois ounce. In making collodion, take any quantity of ether, and dissolve the gun cotton in it; if too thick, it may always be reduced by the addition of more ether. Uniodized collodion may be bought quite as cheap as it may be made; and it generally has the advantage of having been made in a large body, and allowed time to settle, whereby the clear portion only is more easily decanted off for sale._
_Having active professional duties, it has been only at his leisure that_ DR. DIAMOND _has been enabled to give his attention to Photography, which has been the main cause of the delay complained of; but the delay will prove an advantage, for such important improvements are almost daily taking place in the art that works published a short time since are becoming comparatively useless._
HUGH HENDERSON. _1st, Black Japan varnish is very improper for your positive pictures; it often cracks, and is long in drying. Black lacquer varnish, procurable at Strong's, the varnish makers in Long Acre, is the best we have been able to procure. 2nd, The solution for development will keep any length of time; you may use it by dipping or otherwise_.