_The Soiling of the Fingers_ may be entirely avoided by a simple expedient. Use a slightly concave horizontal dish for sensitizing, and a depth of solution not sufficient to wet the back of the collodionized plate, and after the impressed plate {163} has been placed on the levelled stand and developed, proceed thus: instead of holding the plate by the fingers to perform the subsequent processes, take a strip of glass (say five inches long and one and a half wide for the ordinary portrait size), put a single drop of water on it, and carefully pass it beneath the developed plate; lift the glass thereby; the adhesion is sufficiently firm to sustain the plate in any required position for the remaining manipulations till it is washed and finished. COKELY. _Sir W. Newton's Process.--Chloride of Bromium._--May I ask, through the medium of your very excellent journal, what purpose SIR W. NEWTON intends to meet by the application of his wash of chloride of barium previous to iodizing? F. MAXWELL LYTE. _The Collodion Process._--Absence from London has prevented my seeing your Numbers regularly; but in one for December I see MR. ARCHER has used my name in connexion with the collodion process. He states that he called several times, and made me familiar with the process; by which he would lead persons to suppose that he taught me in fact to take pictures. Now I beg most distinctly to state that this is incorrect. MR. ARCHER made, it is true, several attempts in my glass room to take a picture, but totally failed. And why? Because he attempted to follow out the process as he himself had published it. From that time I worked it out by myself, assisted by hints from Mr. Fry, who at the time I allude to was a successful manipulator, and had produced and exhibited many beautiful pictures, and at whose suggestion I commenced it in the first instance. There is also another portion of MR. ARCHER'S letter incorrect; but as this relates to the sale of collodion, I will let it pass, trusting, as you have given insertion to his, you will not refuse space for mine. F. HORNE. 123. Newgate Street. _Portable Camera_ (Vol. vii., p. 71.).--If India rubber should turn out to be what H. Y. W. N. thinks he has found it to be, it would be capable of being turned to excellent account. For instance, instead of having a single "portable camera," which is on many accounts very awkward to use, why should not the tourist have a light framework constructed, and covered entirely with this India rubber: in fact, an India rubber box, in which his camera, and a partitioned shelf containing his collodion, developing fluid, hypo-soda solution, &c., might be easily packed, and in which, by the aid of sleeves, &c., he might coat his plates, and develop and fix them, quite apart from his camera? He _must_ have _something_ to pack his camera, &c. in; and the above-described packing-case would be very light, and also waterproof. J. L. S. * * * * *