"The pyro-gallic acid is generally used now in place of the sulphate of iron that I had indicated; but this is wrong, that last salt forming the image much more rapidly and better, it having to be left less time in the camera. "I believe, then, I have a right to claim for my country and myself the invention of this would-be English process, _and of having been the first to indicate the collodion, and of giving the best method that has been discovered up to the present time_. "From the publication of my process, till my return from the voyage that I had made for the minister, I was little occupied in practising it, my labours on the dry paper having taken all my time. This has been used as a weapon against me, to make out that the first trials before setting out had been quite fruitless, as they had heard nothing more about it. "Nevertheless, I have made my discovery completely public; and if I had practised it but little, leaving it to others to further develope, it has only been to occupy myself upon other works of which the public has still profited. It is then much more ungenerous to wish to take from me the merit of its invention." G. C. _Ready Mode of iodizing Paper._--The readiest way I have found of iodizing the beautiful paper of Canson Frères, is the cyano-iodide of silver, made as follows: Twenty grains of nitrate of silver may be placed in half an ounce of distilled water, and half an ounce of solution of iodide of potassa, fifty grains to the ounce, added to the silver solution. Cyanide of potassa may then be added, drop by drop, till the precipitate is dissolved, and the whole filled up with four ounces of water. This solution requires but a very few minutes' floating upon water containing a small quantity of sulphuric acid; and it is then ready, after a bath of nitrate of silver, for the camera, and will not present any of the disagreeable spots so noticed by most photographers. This paper is probably the best for negative pictures we have at present; although, if very transparent paper is required, oiled paper may be used for negative pictures very successfully; or paper varnished is equally good. The oiled paper may be prepared as follows: Take the best walnut oil, that oil having less tendency to darken paper of any other kind, and oil it thoroughly. It must then be hung up in the light for a few days, the longer the better, till quite dry. It may then be iodized with the ammonio-nitrate, the ammoniated solution passing more readily over greased surfaces. The varnished paper may be prepared by half an ounce of mastic varnish and three ounces of spirits of turpentine, hung up to dry, and treated as the oiled paper in iodizing; but both are better for resting a short time previous to iodizing upon water containing a little isinglass in solution, but used very sparingly.