Varnishing. By any convenient method heat the negative gently and evenly, until the hand may be borne upon it without pain. Now. from the varnish-bottle, pour upon the centre of the plate a pool of varnish, in the same manner exactly as the collodion is applied. Pour

From the developed picture we must remove the sensitive material, iodide and bromide of silver, on the one hand, in order to make the plate transparent; on the other hand, to protect it against further changes through the influence of light. Dr. H. W. Vogel.