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598 THE PHOTOGRAPHIC NEWS. [December 11, 1863. Has Mr. Busch thoroughly examined that process which he stigmatizes over freely, declaring that it “ does certainly not look like a step in advance,” and settling that I * “ only substitute painting them (thephotographic images) over with colours,” which latter process, he is “ afraid, is decidedly the better ?” Evidently, Mr. Busch does not know that, in con demning my chromophotography, he speaks against his own interests, otherwise he would not drive the photographers to the abolition of the toning process, he who is a manufacturer of cloride of gold, if I mistake not. Hence Mr. B. ought to know very well that the solution of this salt is colourless, and therefore you cannot paint with it, though you may tone with it; and, as a chemist—even if he has not read the theory of toning by Messrs. Davanne and Girard, now pub lishing in your jonrnal—he ought to know that the tint produced by gold is effected by substitution—“ a portion of gold is deposited, a portion of silver is dissolved, and gives place to the gold.” Consequently the image preserves all its original purity, while water or oil colouring, which he is afraid is decidedly the better,” is a process of superposition, which covers the photograph with colouring matter extraneous to the sun printing, and debases the exquisite merit of truth, hides the delicate lines of the picture, seeks to trick you into believing it to be the wonderful effect of chemicals and light, when it is nothing but an abortion that is not worthy the name of a picture or a photograph. If Mr. Busch is contented with this sort of hybrid produc tion, let him enjoy a satisfaction I cannot envy him. And, in fine, as Mr. Busch modestly reserves to himself, in his quality of chemist, the privilege of solving the problem of photography in colours, excluding from such studies all us ignorant photographers. We wish him full success in his researches; and if, after a long and painful incubation, should they give birth to a little mouse, still it will be a mouse, and we will never say that “ it does not look as a step in ad vance.”—Yours, L. Colonel C. Baeatti. Milan, 6th December, 1863. • Photograyhic plates u Queries. Coloured Photographs, or Double Toning. Dear Sir,—I noticed in your last impression Signor Ricco’s and Colonel Baratti’s dispute of priority on colouring photo graphs by toning process. I trust that I may be allowed to re mark that the invention (as it is called in Galignani's), is not a new discovery, inasmuch as any one who has been familiar only for a short time with photo-toning, must surely have noticed the different hues obtained by the various degrees of toning, and fixing with or without toning, by hypo, ammonia, &c., &c. The novelty, however, might consist in the application; but this, too, is misunderstood ; and at all events, of no practical use. No doubt we may tone the face one colour, the coat of another, and so on, but it will always represent the portrait of some one afflicted with yellow or other fever. There is nothing more difficult to render truly as in nature, than the blooming com plexion of a fair lady in all its delicacies of light and shades. How, then, could a manipulator, however skilful he might be, produce softness and vigour, almost on the same spot; .insen sible gradation and variation of tints ; minute sharp touches of shade, outlines neat and true, and solve many other artistic difficulties by means of a bath or solution ? Moreover, if we have to use the brush in toning, it will be far better to use it comfortably, with the aid of stick and easel, in plenty of white light, when the artist can mix, judge and alter the pigments at his own fashion and fancy, better than in the yellow or gas light. Last year I tried more than once to utilize such a method of fancy toning, but as my time is not my own, it was not until last spring that I succeeded to something worth mentioning. In the ma vario e conveniente. Iritrattiguadagnano maggiorvita quando, vengono trattati con questo metodo.” 2. See a letter on the same subject in the Camera Oscuro, page 143. 3. Vid ind., page 178, etc. * I do not say our, because I alone have published the process in question, and the Galignani took his quotation from an article of mine in the Camera Oscuro, and the public and myself are, as yet, ignorant of any other publication of that kind. usual gold solution, I toned a whole-plate portrait of the Prin cess Alexandra, with the only difference that I made the hair of a rich fox hue, and the ribbon binding it behind of a, pinkish tint. Again, a whole plate portrait of Lydia Thompson, the hair of a decided golden colour, and the coronet of a rich velvety true purple. I was pleased with it, and 1 named it double toning, from its relation, double printing, and showed those and few similar experiments to my principal, but as it was not a question of L. s. d. to him, it was there and then condemned as losing time in playful (nonsense. Although my friends admired very much the pleasing contrasts of double toning, yet I could not see in it any practical use. Lately, however, I found out its application, and very beautiful it is too. If landscape views are toned gradually from very cold to very warm tones, a skilful manipulator may produce such effects that no artistic brush or crayon work can compete with. There you can obtain the truo effect of sunrising and sunsetting ; you can represent the effect of q conflagration ; and many other very beautiful artistic con trasts can be managed. The enclosed I venture will give you an idea of what I mean, and although very poor, imperfect and bad proof, yet you will be able to judge that the appli cation is true, and of the vast new field, which is opened to photo amateurs to show their artistic feeling. I shall bo thankful of your opinion thereon. Apologising for trespassing on your valuable space,—I am, dear Sir, faithfully yours, P. T. Cozzo. [The question is, will the results to be obtained be commen surate with the trouble? Doubtless the process may occa sionally find useful application, and we have seen some pretty effects.—Ed.] Measure of the Angle, &c. Sir,—I have seen a good deal of correspondence lately in the Photographic News concerning the angle included in various lenses. Surely there is nothing more simple than to get the correct angle of a lens with the prismatic compass, which I have always used for that purpose. I follow the simple plan of placing the prismatic compass on the top of my camera; when requiring the angle contained by the lens, I focus sharp (as near the left edge of the focussing glass as possible) some con spicuous building, such as a church. I then take the bearings of the church, or building, and then, having marked some point (probably a tree) which is perfectly sharp on the right hand side of the ground glass, I take the bearings of that. I then deduct the number of degrees of one from the other, and the result is, I imagine, the correct angle contained by the lens. I have used your chloride of lime toning bath with great success. I found adding a few grains of acetate of soda an im provement.—1 am, sir, your obedient servant, H. DUBEELY, Major 8th Hussars. Simla, East Indies, October 1 st, 1863. [To obtain certainty by this method, it is necessary that the compass be in contact with the optical centre of the lens. With the triple the place of the stop is near enough. Nitrate of Soda in the Printing Bath. Sir,—As a photographer, I have for a considerable time felt great interest in the discussions now going on in various photo graphic societies, on the strength of floating bath necessary to secure the best and most uniform results in printing. Professionals and amateurs are alike at their wit’s end, by the very opposite results arrived at by different persons, using even the same formula?; this is particularly the case in using nitrate of soda ; one gets prints of unsurpassed brilliance on an 80-gr. soda, and 30 or 40 grs. silver, while another, (to wit, “Cantab,” in last week’s News) finds that, with the same materials, and in similar quantities, his albumen is dissolved from the paper! Now the experience of “ Cantab’’exactly corresponds with my own. Being anxious to try the soda nitrate bath, I added 30 grs. of that material to a 40-gr. bath. On floating old albumenized paper on this bath for 4 minutes, I got tolerable prints, but not equal to a 60-gr. bath with 2 minutes’ floating. I then tried some new Rive paper, No. 48, when the albumen immediately dissolved off in patches, covering the surface of the bath with transparent froth. Determined not to bo done, I added silver to make it up to 80 grs. nitrate silver, still the addition of soda originally made, caused the albumen to dissolve. I then added