Replies and Discussions.

ON THE KEEPING OF PLATES-WET PROCESS.

"CONSPICUOUS by Absence" seems to have created a disturbance in the minds of some of my photographic confrères as to "how a wet plate could possibly bear an exposure of 90 minutes out of doors." Certainly those photographers must be in the very infancy of their practice who cannot understand such a simple, very simple, assertion. Not understand an exposure of "90 minutes!" Why, it is enough to make a photographer's "cat laugh." Well, let us go back to the days when, photographically speaking, we were in pinafores, and caught hold of the nurse's gown to assist our tottering steps.

Once upon a time (is not that right, Mr. Editor? children's stories used to begin thus) there was a chemist of the name of Thomas Perry, who made a collodion called "Xyloiodin." This collodion had two very valuable properties, viz., one of rendering objects in deep shadow with exquisite half-tone and delicacy; the other of keeping the plate moist for a period of three or four hours. But it lacked one thing, without which it was comparatively useless. It wanted density, or that amount of opaqueness which is necessary to the production of good printing negatives. There lived some time ago, and does so now for aught I know, at Bristol Bridge, a chemist, of the name of Ponting, who produced a collodion that obtained great fame, and gained a prize medal at the International Exhibition of 1862, held in London, which was conducted on fair and honourable principles. This preparation gave exquisite pictures of great density, combined with half-tone, but it lacked one thing, viz., the property of keeping the plate moist during exposure. Looking at these two collodions in a common-sense view, you would say, Mix them together. Just so; that is what I did; but that was not all, for I found that where the two were mixed together they did not work at all; in fact they were like a man who had taken too much of "something" too strong for him. The body would not keep intact, it would not stay on the plate, it always had a wish to tumble down the sink, or "skedaddle," as our Yankee friends say, the wrong way. Old Photo's would say, "Too new"-"Wants age"-"Not matured"-"Not ripe enough,"-"All wrong," for I always got mine four or five years old before I even mixed them together. Well, how was this to be remedied? Thus I added an equal quantity of Rouch's plain collodion (Hardwich's make), and, after being well shaken, and standing six weeks, it was decanted into a clean bottle, all that was wanted, it was then simply A 1. Whether Mr. Perry be alive I cannot say, but the methylated "tackle" put forth by him and Mr. Scholfield would not do at all. The original collodion of Ponting and Perry was made of pure spirit-Rouch's is also-and anyone, in my estimation, who desires to do "fine" photography, and keep their negatives intact (i.e., free from honeycombing, reticulated cracks, &c., &c., or markings on the film when using a good lac varnish), and who does otherwise is foolish. To satisfy the demand for cheapness, to enable everyone, whether he be an artist or not, to enter the lists, and compete on equal ground with others, was the reason of the methylated being so largely introduced. Only last summer, Mr. Savage, of Winchester, Mr. Cummings, of Sidmouth, and others, wrote to me, finding serious fault with the collodion of a celebrated maker from this cause. On my suggesting to the latter gentleman the advisability of his diluting his collodion with some of Rouch's plain, the evil was removed. To enter into the reason of this is not my present purpose, but I say to all who desire fine results free from failure, Don't use methylated collodion. "Evil communications corrupt good manners."

And now, just one more word upon the circumstances under which Conspicuous by Absence" was taken. In all similar situations there is always more or less a draught which just twitters and stirs the leaves. Now, if you closely look into the photo of this picture, you will observe very little movement. The plate was prepared in the ordinary way, well backed up with damp blotting-paper placed in the camera, and exposed in

the ordinary way, I standing beside it, watch in hand, the whole time. At the slightest intimation of a general movement of the leaves, the lens was capped; and during the exposure of 90 minutes, it was so capped 160 times, and the seconds thus lost counted for each time, and allowed for in the exposure. I have not gone into a discussion upon bromides and iodides, because I have no time. I trust I have made myself clear to the comprehension of every one of your readers. I would only add that true photographers must stick to truth; for the vital principle of photographic success is antagonistic to falsehood. Few, very few, know or feel what that principle is, forgetting it is that which governs this universe of ours, which gives beauty alike to our productions and our actions, and guides and directs our steps for good or for evil.

PROFESSOR ROSCOE'S EXPERIMENT.

W. H. W.

SIR,-In the last number of THE ILLUSTRATED PHOTOGRAPHER, you give an account of an experiment performed by Professor Roscoe at the Royal Institution, to illustrate the process of development, and mention the fact of my having performed the same experiment before. This is true, but I have not done so in public; therefore, no doubt, the learned professor designed and carried it out as an original experiment. As I did not operate exactly as described in your journal, will you allow me to lay before your readers the method adopted.

I first made a thin trough or bath, one side of which was of yellow, the other of white, glass. This was of the same size as the ordinary magic lantern slides, and was of course made water-tight. To use it, a plate is exposed (I prefer to expose it in a small camera, for the sake of sharpness), and, the trough being filled with a weak solution of iron, with a large proportion of acetic acid, is placed carefully in it. The slide is now inserted in the lantern, of course, with the yellow glass side next the condenser, when the picture is projected upon the screen in the ordinary way. There need be no hurry in thus performing the experiment, as the development may be made as slow as may be desired, by weakening the solution and increasing the proportion of acid used. This is very pretty experiment, and I intend trying others in the same direction in sensitising plates, as I think we may possibly learn something as to the cause of various stains and markings, which often occur in this part of the process. Of course, in performing the development experiment, the plate should be placed the right way in the bath—that is, upside down-so that it may develop the right side up on the screen.-I am, sir, yours respectfully,

JAS. C. LEAKE.

MARKINGS IN THE COLLODION FILM.

WITH reference to a letter which appeared in our last week's issue (see page 97), Mr. Collings writes to say that the curious markings referred to, arising from a stream of water falling unequally on a non-fixed negative, before intensifying, was to him very puzzling. Like our correspondent, J. C., he had often to take a number of negatives in rapid succession, and when satisfied from the first iron application that one was right, he placed it at once under an ordinary flower-watering rose-tap, soldered to the water-pipe, while he prepared another plate and put it into the bath. When he came to intensify the non-fixed" negative placed under the rose-tap, he found that, where the little streamlets fell direct from the holes in the tap, scarcely any intensification could be got, while the other parts of the negative, where the water merely swilled over, could be readily intensified. He attributes this non-intensifying capability to the oxidised iron borne down on the plate by force, through the little holes, and he also says, that when his attention was drawn to the subject, these marks, or round spots, could easily be seen before intensification commenced.

Can it be that a strong stream of water exercises a solvent action on iodide or bromide of silver? Does peroxide of iron have a similar effect, or does it merely cover or protect the surface on which it has impinged from the action of the second developer? After all, the rose-taps referred to by our correspondents, may have been tinned iron, or perhaps zinc. Nevertheless the facts stated open a wide field for inquiry.

Mr. Holman Hunt's new picture, illustrating Boccaccio's novel of "Isabella and the Pot of Basil," will be exhibited in Mr. Gambart's room, King-street, St. James's, for private view, on the 16th, 17th, and 18th of April next, and to the public on the Monday next following, the 20th of that month. Mr. Blanchard is to engrave the picture in the line manner.

Bits of Chat.

The officers of the Royal Artillery have taken M'Lean's Gallery, No. 7, Haymarket, from the month of June next, for the purpose of exhibiting original pictures, photographs, and sketches, the work of members of the corps.

Mr. Carey Lea says, in a letter to a contemporary, "I notice that Mr. Sutton asserts that his plan of walking-stick cameras is to be carried out by a well-known optician. The great fault of pictures taken by short-focus lenses arises from the fact that they are, in almost every case, brought too near the object to be photographed, and the result is seen in the ridiculous views commonly produced by such. Should this new method ever be carried out, it will succeed only by paying attention to this principle, and excluding very near objects from the foreground. The cause of the mistake so commonly made appears to be this -that with short-focus lenses the depth of focus is so great that near objects can be got into focus at the same time with distant ones, and therefore it is thought just as well to let them come in. It is a mistake, however, to do so, and in this way many pictures are rendered unnatural. Whether anyone will seriously take the trouble to take little one-inch views for the purpose of enlarging them, when each copy is to be separately made in the camera, developed, and transferred, seems to me in the highest degree problematical.

The true course to adopt for the end here proposed would be first to print positives from the small pictures, and then to enlarge these positives into negatives. With nice work a picture two inches by one inch and a half might be enlarged to a half-size plate, or possibly even more.

What Mr. Sutton has to say about the imperfect rendering of details in photographs on albumen paper is perfectly true, and he justly ascribes this fault to the want of smoothness of the paper after sensitising, as, in fact, I pointed out some months ago, in an article on "Pressure Frames." I there endeavoured to show that the only remedy we had for this evil was to press the paper closely up to the negative, by means of well-constructed frames. None, I should think, but the most superficial observers can imagine that as good an effect can be got by a light pressure as by a considerable one. One must be easily satisfied, in respect of definition, to put up with those imperfect contrivances. Just £15,000 are called for, in 150 shares of £100 each (with power to increase in due season), to carry out the objects stated in the subjoined extracts from the Register:"For purchasing from John Robert Johnson, of 3, Red Lionsquare, and from Ernest Edwards, of 20, Baker-street, Middlesex, the beneficial interest in the contract which they have entered into with J. W. Swan, of Newcastle-upon-Tyne, for the purchase of his patent for printing in carbon or other permanent pigment, &c.; and also the beneficial interest in certain contracts for the copyright of sundry pictures to be printed in permanent pigments; and the working the said patent. The reproduction and printing of pictures, &c., by the autotype and other processes, &c."

ron.

The "hangers" of the forthcoming Royal Academy Exhibition will be Messrs. Maclise, Sydney Cooper, and CaldeMr. F. Goodall will exhibit two pictures-1. "The Purification after the Birth of Christ," in which the Virgin is represented as going to the Temple with doves in her arms; in the background is the entrance to the Temple. 2. Mary, after the Crucifixion, in the streets of Jerusalem, leaning against a stone wall, and clasping her hands in passionate grief. Mr. Mason has just completed a picture, called "The Evening Hymn," which will probably appear at the Royal Academy Exhibition. The work is the largest yet shown by the painter.

Fun remarks:-"The man who publishes a book knowingly submits to criticism, and I do not see any reason why he who publishes-or authorises the publication of-his photographic portrait, should be held exempt from wholesome comment. If the reviewer may condemn Mr. Dixon's "Spiritual Wives," I cannot see anything to prevent his censuring Mr. Algernon C. Swinburne's latest carte. That gentleman has been often at great pains to make us forget that he has poetic power, but he has hitherto been original even in his weakness. But now he descends to a feeble imitation of Dumas, and the photographic shop-windows teem with cartes in which the author of Atalanta ogles the actress of Mazeppa!"

At the last meeting of the French Photographic Society M. Romain Talbot described a process in which the plate, simply excited, washed, and dried, is said to possess excellent keeping properties. Some negatives were shown on plates which had been preserved six months. The plate being cleaned and coated with a collodion described as M. Harnecker's, was plunged into a bath containing about fifty grains of silver to the ounce, and one drop of pure nitric acid. The plate is removed and drained, washed in distilled water, afterwards with ordinary water, and again with distilled water, thorough washing being essential to success (water of a calcareous nature must be avoided). It is then dried at a temperature of about 90° Fahr. The exposure is about thrice as long as that a wet plate would receive. The development is conducted thus:-Plunge the exposed plate for from five to ten minutes into a bath of distilled water, and from thence into the silver bath, plunging the plate in and out four or five times; and then develop with a solution composed of sulphate of iron, 75 grammes; water, 1,800 grammes; glacial acetic acid, 45 grammes; absolute alcohol, When all the details are well out, wash well, and continue to develop with a solution of pyrogallic acid, 1 gramme; distilled water, 225 grammes; glacial acetic acid, 10 To which is added nitrate of silver, 1 gramme; grammes. distilled water, 48 grammes; glacial acetic acid, 1 gramme. Continue with the last solution until the negative shall have acquired the strength desired. Fix with hyposulphite of soda, 1 gramme; water, 3 grammes; and finally coat with a dilute solution of gum, and dry the plate.

60 grammes.

Most photographers are fond of making experiments, and many have found out to their cost that the making of the various little pieces of apparatus requires and involves a serious expenditure of time and labour. To those engaged in photographic experiments, Mr. How's Catalogue will be welcome, as a glance over its pages will show them that they may purchase, at the cost of a few pence, many little pieces of apparatus which would be very useful to them, but of the existence of which they are ignorant, and many others which would cost hours of labour to make, and which would be more or less imperfect when finished. For instance, on page 5, we find beakers of German glass, clear and white, which are not only useful for filtering solutions into, but which make capital measures for solutions, if the operator will take the trouble to scratch a line or two on them with a writing diamond. Then on page 9 we have precipitating glasses; and the use of these would often save the photographer no end of filtering of developing solution, &c. All he has to do is to pour his developer into one of these overnight, and in the morning pour off the clear portion for use, which he can do without disturbing the sediment. Again, on page 17, we find various drainers and funnels of Berlin porcelain, without necks, which are not only strong, but which support the filtering paper, while they allow the solution to run freely through the holes in the sides, instead of through the neck, as in the old form; thus saving the trouble and annoyance so often met with when the filtering paper breaks, which it generally does, when nearly the whole of the solution has run through. On almost every page there is figured some little instrument which would be of use to photographers, and we should advise all who are experimenting to procure a copy of it for the laboratory.

The danger that sometimes arises from the incautious use of oxygen and hydrogen gases by unpractised hands is a cogent argument for some more simple and manageable source of artificial illumination. The magnesium light has been used by some with great satisfaction, but is yet far from perfect in the character of the light produced, as well as in the mechanical provision necessary for its combustion. Magnesium cylinders are expensive, and this question of expense is perhaps the greatest difficulty to be surmounted in all applications of artificial light to photography. We remember prosecuting some experiments in this direction some few months back, in company with an experienced photographer, who was at that time groping his way out of the many obstructions that surrounded the use of artificial lights in photography. Without enumerating the many experiments more or less successful, we may state for the benefit of those interested, that we obtained the greatest effect by the light resulting from the combustion of phosphorus in oxygen gas. The method of proceeding is sufficiently simple to be at once understood. A large glass receiver was filled with oxygen gas, and phosphorus was burnt within it, in the same manner as in lecture-table experi

ments.

The negative already prepared, with its accompanying sensitive paper beneath, was exposed to the action of this light with the most satisfactory results. The inconvenience, if any, is the chance of breaking a large gas jar, worth, perhaps, 5s. or 7s., which would occur, perhaps frequently, even with proper precautions, and render this light far more economical. But this might be remedied by having a metal box or cylinder, made with an aperture in front, which could be glazed or not, but by preference glazed, or the aperture might be fitted with a lens to condense the light, and render it more immediate in its action. This plan will be found to answer well, and to be within reach of all; it has the great advantages of being free from any chance of explosion, of being available at any moment, of being within the compass of the many, and of producing a most intense light, of extreme purity. We have not tried a metal combustion chamber; in our experi ments the combustion of the phosphorus was conducted in glass receivers, and gave, of course, a largely diffused body of light. The phosphorus should be wiped quite dry before it is ignited, and placed within the cylinder to prevent its being thrown about, and to prevent irregularity in the rate of combustion. In circumstances where the electric light cannot be commanded, this will perhaps be found valuable-pro publico. — Penny Mechanic,

A journal in New York has been started which, with true Yankee ingenuousness, calls itself The Magpie, and sets forth its thievish proclivities in the following plain terms:"Look out for The Magpie! A fortnightly journal, compiled from the comic, humorous, and satirical periodicals of Europe, with illustrations copied by photo-lithography."-Fun.

Meteorological Heport

FOR THE WEEK ENDING APRIL 1ST, 1868. Taken by Messrs. Negretti and Zambra with Standard|| Instruments, at their Establishment, 153, Fleet-street. Observations taken at 10 A.M.

The readings of the maximum thermometer and amount of rainfall refer to the day preceding that on which they are tabulated.

During the past week barometrical pressure has been unusually high, and continually on the increase, until the 29th ult., when it will be seen that the barometer commenced a gradual, but continuous and steady, fall, not amounting to enough to cause any serious apprehension of a great change in the present weather, when reference is made to the amount of moisture present in the atmosphere, which will be seen to be getting less, as the slight decrease of pressure continues. The wind, too, although slightly backing this morning, is still in a favourable quarter to encourage a belief in fine weather; and unless the wind should be noticed to continue its backward course, accompanied with a still falling barometer, the probability is that a continuance of the present fine and seasonable weather will continue for some days.

To Correspondents.

RECEIVED." Photography and Archæology," by J. Henderson; "Photographers we have Known," by "Democritus; "Photography in America," by J. H. Wills; "Photography," by George Benister; "Once a Month," by Our Gossiping Photographer; and a print washing machine, by J. Collier.

A WARM FRIEND.-1. Rice glue is a very permanent, delicate cement, used by the Chinese for making their domestic gods, and other ornamental and useful articles. It may be easily made, we are told, by mixing rice-flour with cold water, and letting it simmer gently over a fire. When dry it will receive a high polish, and have a very smooth, even surface. It has been used in photography as a substitute for albumen in the preparation of paper. 2. Soluble amber is described as closely resembling Canada Balsam. The amber

is melted, and its weight of linseed drying oil incorporated with it. 3. We have heard of horn paper, but do not remember having ever seen a specimen.

A SCULPTOR. - If you are a judge, and know how to choose a good article, the more economical course may be safely adopted, if not, the more expensive instrument may prove the cheaper in the end. Let us hear from you again, and we will then, if you please, reply privately.

J. BRETT.-A distemper-coloured background may be so prepared :-Strain whiting and throw it into clean water, enough to cover it. the calico or linen tightly over the wooden frame. Break up some common When it is thoroughly softened, and of a pulp-like consistency, pour off the surplus water and mix it well together, to be sure that it is smooth and free from lumps or grittiness. Add the colour and mix with size in the proportion of rather less than one part to three, stir well, and leave it for about twelve hours in a cool place. Use it cold, and while it is in a jelly like condition, and it will dry flat

and smooth.

ARCHER CLARE.-Mr. R. A. Seymour desires to acknowledge the receipt of your note, with the thirteen photographs, some of which he will have pleasure in using.

PHOTO.-Mr. Wall gratefully acknowledges the receipt of half a five pound note in aid of the British Association of the Blind.

M. A. DE CONSTANT DELASSERT is informed that Mr. Sutton's present address is La Pavillon, Redon, France (Ille et Vilaine), and that he will be happy to correspond with him.

COLOURIST. Our "Column for Young Colourists" is unavoidably postponed.

ARTHUR HUTCHISON.-You will find the names and addresses of such reliable dealers in our advertisement pages.

CLEAVER'S PHOTOGRAPHIC SOAP.-The above and several other correspondents want to know where this is sold. It may be obtained from John Sanford, Red Lion-square.

E. D.-Respectfully declined.

J. F. C.-We are unable to obtain the information.

C. HOPE.-Mr. Ross will doubtless announce the apparatus for sale in our columns when it is complete. See Mr. Sutton's paper in this week's issue, and Negretti and Zambra's advertisement.

E. ROPER.-The accident which prevented our insertion of "The Jottings" last week, had nothing to do with your process of engraving.

L. FETWILL.-In developing the Liverpool dry plates, you have omitted a most important preliminary, which is essential to full success. You did not first moisten them with equal parts of alcohol and water. Unless you do so, the film is apt to wrinkle up during development, and is very difficult to fix. 2. We believe these plates will keep well for some months, and perhaps much by Mr. Dawson in this week's number. He is yet in some doubt as to the best

longer, if they are secured from the access of air and moisture. 3. See article

method of developing Dr. Hill Norris's rapid dry plates, but promises to give some information soon.

ANSWER TO “—." We have referred your question to Mr. F. M. Waller, of the Thames Plate Glass Works, who informs us that there are two ways of restoring the surface of your plates. The first is chemical. You can renove the partially decomposed surface, by a careful use of hydrofluoric acid, which, however, should be very much diluted. A second, and safer plan, is a mechanical one, by which the attacked surface is removed by polishing. Take a block of wood, of convenient size, and cover it with soft felt, or washed leather; sprinkle this with a powder known as "Crocus," wet the plate and the rubber, and polish until a good surface is obtained. The plate should be firmly fixed on a strong table or bench. Care should be taken that the powder is very fine, or the plates will be scratched. A good plan is to throw it into a basin of water,, and after allowing it to stand a few minutes, to pour off the upper portion, which will contain all the finer powder; allow this to subside, and use as above described, throwing away the coarser part, which would scratch the plates. Are the plates worth the trouble?

DR. VOGEL'S ACTINOMETER.-Some correspondents who write, disputing the originality of this instrument, are referred to an article which will appear next week.

J. Ross. We are informed that the gentleman, although one of the editors of the journal in which the appeal to photographers for the Hardwich Church Fund appeared, was not a trustee, nor, so far as we know, a subscriber, and that the statement is quite correct. The ott er matter referred to with respect to the necessitous widow, is also quite correct, as given in the communication at page 77. It was a private sub-cription. The Goddard Fund is another matter. That will soon be settled in a court of justice, between the trustees and the executors of the late Mr. Goddard. E. RENSHAW.-So far as we yet see, we cannot recommend permanganate of potash for rectifying old nitrate baths. These new " "dodges cannot be definitely settled in a hurry, and we should be loath to give an absolute opinion till our experiments are completed. This will answer J. Roge: s

and E. P.

AN INDIGNANT READER.-We reply in the recently uttered words of G. Hardy, Esq., M. P.: "It is, I presume, very well known that many letters are published in newspapers anor y mously-nay, it is the commonest thing for gentlemen to have their letters published without their names being attached to them, at the same time to furnish their names privately to the editors, with the intention of coming personally forward to substantiate their statements in case they should be questioned." We have the name of the gentleman who wrote the article, and that is enough. THOMAS PARSONS.-At page 87 you will find this subject has alre dy received attention.

G. L. M.-An ordinary whole plate portrait lens would answer your purpose. There are so many lenses by various good makers equally suitable that we must refer you to our advertisement pages. Several dark tents will also be found there, and so much depends upon what you require that we barely know how to advise you.

E. B. FENNESSY.-Thanks. The proof shall be forwarded. Mr. Wall is making a sketch from one of the photographs, for the continuation-h. nee the delay.

Our columns are so crowded, that several corresponde..ts must be answered next week,

LONDON, APRIL 9th, 1868.

caoutchouc,

PHOTOGRAPHIC NOVELTIES.

BY TEO JAS SUTTON, B.A.

O many photographic novelties and important indications of progress are occurring at once to claim our attention, that we encounter them at every turn. All parts of the photographic horizon are bristling with them. I am really compelled to interrupt my articles on landscape photography, in order that I may tell the reader some important news which the post has just brought Two letters have arrived this third of April-one from Mr. Pouncy. the other from M. A. Marion-the former smelling characteristically of turpentine, and the latter of M. Marion's letter contains what I very much wished to see, viz., some sheets of his vitrified caoutchouc. A few months ago I said in my Notes, that photographers sadly wanted a perfectly transparent paper, which should be as clear, colourless, and flexible as glass; and that fortune awaited the discovery of this substance, and would certainly reward the lucky man who should solve this problem. And now it has actually been solved, and I have sheets of the very material for which I sighed lying upon the table before me. They are as clear and transparent as glass, and as strong and as flexible as the thin sheet of foreign paper upon which I am now writing. Let the reader amuse himself by considering the many uses to which such a material can be applied; and in doing so, let him regard the sheet of vitrified india-rubber as a thin flexible sheet of glass, which will not break. He may transfer a negative to it, or he may attach the sheet by its edges to a glass plate, and take a negative upon it direct, without any fear of the collodion film splitting, or wrinkling, or blistering in the development. What a convenience to the tourist to be able to dispense with a load of glass plates, and to avoid, at the same time, the risk of breakage of the negatives. That tannin negatives can be easily transferred to such a substance, I have the proof now before me; for, a few days ago, M. Revon, a banker at Grau, on the Saone (one of my old subscribers to Notes), sent me in a letter two tannin negatives transferred to paper; and that all collodion negatives can be thus transferred has been proved times without number, I have myself frequently transferred negatives to films of gutta percha, formed by dissolving that substance in chloroform. Then again, how easily curved panoramic negatives might be taken upon flexible films of vitrified india-rubber, which could be used flat in the pressure frame. But in positive printing its uses are equally important. Valuable silver prints may be hermetically grated between two sheets of it, and thus be protected, both from the action of the air and of the anti-chlor in the cardboard; and carbon prints can be taken upon it, both by Pouncy's printing-ink process, and by the bichromated gelatine process. In the latter case, some of the most troublesome transferring operations in Mr. Swan's process may be dispensed with. I have read in this journal about a new company which is being formed to purchase Mr. Swan's patent, and carry out his process commercially on a large scale. There is to be a capital of £15,000 raised by 150 shares of £100 each. Let ny readers pause before they have anything to say to this undertaking. M. Marion has himself suggested to me, in his letter, a new carbon-printing process, in which his sheets of vitrified india-rubber play an important part; and he has sent me an excellent carbon print taken by this new process. In another column will be found my translation of this portion of his letter. It is

Vol. I.-No. 10.

no secret, because he tells me that he is going to describe the new process at the meeting of the French Photographic Society, which takes place in Paris to-night.

Besides the sheets of vitrified rubber, M. Marion's parcel contained some sheets of waxed and collodionised paper, with instructions for use. It was upon this kind of paper that M. Siloz took, last summer, the entire panoramic view which I described in my Notes, as including, at four operations, the entire sweep of 360 degrees. The negative was a perfect little beauty, a yard long, and about five inches wide, and was taken with my panoramic lens. Those amateurs who prefer to take large negatives direct in the camera, instead of enlarging from small ones, should by all means give this paper a trial. I have never seen paper so beautifully waxed, and showing so little granulation. The collodion which is applied to it, contains both a bromide and an iodide; and the paper is excited by immersion in a nitrate bath, then washed, and developed by gallo-nitrate. It has a very pale yellow tint, and not the deep purple tint of common iodised waxed paper. I hope soon to have a special article on the use of this paper; but, as I said before, interesting novelties crowd upon one just now.

Mr. Pouncy's letter contains the gratifying assurance that his printing-ink process is at length beginning.to move ahead in its commercial career. His specimens in the Crystal Palace have excited much attention; and a Government official of eminence has lately called upon him to witness the manipulation of the process, and has expressed himself satisfied with the proofs. When we consider the great capabilities of this printing process, the simplest of any, and that it yields the most permanent proofs, and has the widest range of application to a variety of purposes, we must all surely feel pleased at hearing of the chance which there now seems to be of its proving a commercial success.

The reader will find in the present number separate articles by me, on M. Marion's new carbon printing process, and Mr. Pouncy's method of printing in oil colours.

MORE EXPERIMENTS WITH DRY PLATES. BY GEORGE DAWSON, M.A., LECTURER ON PHOTOGRAPHY, KING'S COLLEGE.

ANOTHER field-day with Mr. Collings at the celebrated Purley Oaks, near Croydon, completes my first series of experiments, and sets at rest any doubts I entertained on the comparative sensitiveness and efficiency of certain dry processes which I proposed making the subjects of thorough testing.

The "Purley Oaks," I may observe, are almost unknown to photographers, although they are more striking in character, and much more easily come-atable by the London amateurs than the Burnham Beeches. If the graphotype process is suited for the representation of majestic and grotesquely gnarled oak trunks, I hope "our" artists will try their hand on copying some of the excellent negatives I have obtained, and thus convey to my readers at least some impression of the picturesque objects lying so near London.

On this occasion Mr. Collings and I started from London on the photographic van at an early hour on Monday morning, March 30, and reached the Oaks about half-past nine a.m. When we arrived a haze prevailed, but before an hour had elapsed it had nearly cleared away, and thereafter we were soon at work.

As in my previous trials in the field against Mr. Collings's wet plates, I adopted the plan of regulating my exposure by his, and giving, for each plate, either the same or a longer time, according as my previous experience with the same plates suggested.

Out of sixteen dry plates exposed during the day I have developed twelve, and from them obtained eight good negatives, viz., two by Russell's rapid tannin process; two from "Liverpool" plates; one from Norris's extra sensitive plates; one by "Sayce and Bolton's" process; one from ordinary bromo-iodised collodion, coated with tannin, and