know of each others failures and successes more frequently, the intercourse would be found both pleasant and profitable.-ED.]

ALKALINE DEVELOPER-FLAT BATHS AND PRINTING.

SIR,-I observe in Major Russell's article, in your last number, at page 186, the following remark:

"Iodide of silver is inert to the alkaline developer."

This statement, if I understand it rightly, is contrary to my own experience. I have many times developed, by the alkaline method, negatives upon iodised collodion, which were excited in a bath containing no bromide of silver. The alkaline developer brought out the usual pale image, which was then intensified by silver. The negatives showed no signs of fog. The method did not appear to shorten the exposure, or to have any advantage over the common mode of developing iodised tannin plates; but I wish to record the fact that iodide of silver is not inert to the alkaline developer; for if it were, no pale image could be obtained by that method.

Will Major Russell kindly explain this inconsistency in our results, and, if necessary, try the experiment which I describe? In another part of his paper he recommends a flat bath for exciting the plates. I would remind your readers that a very convenient flat bath for exciting plates is manufactured by Messrs. Edwards, of Dalehall Potteries, Burslem. It can be purchased at any of the leading photographic depôts. This dish (which, by the way, I ought not to call a flat one) has a bottom like an extremely obtuse letter V. Open the V until the lines include an angle of about 160°, and you will form an idea of it. Baths of this kind have many uses in photography. French photographers very commonly excite their plates in a flat bath.

The same firm also manufacture vertical nitrate baths, constructed to stand in another vessel containing either hot or cold water; also horizontal baths on the principle of hot-water plates. Very useful articles these, particularly the latter, for the toning and fixing solutions. Many a toning bath is thrown into the waste-pan, which would act well if the temperature were raised a few degrees; and many a print has been improperly fixed, in consequence of the hypo solution being too cold. Now that the hot weather is coming, many troubles may be avoided by placing the nitrate bath in a vessel of cold water. Temperature is an element not sufficiently attended to in photographic operations.

A word or two in reply to the remarks about weak nitrate baths; I merely attempted to explain a fact which seems to be supported by a great weight of evidence. My own experience with weak baths is but small, and the little printing which I do now is generally done with a strong bath. But I know many printers who invariably use a weak bath, and turn out fine prints, the Misses Bertolacci for instance. The strong bath always, in my hands, gives greater sensitiveness than a weak

bath.

When a weak bath is used, it is important to dry the paper thoroughly before the fire immediately before exciting it. A little atmospheric moisture in the paper seems, however, to be an advantage during the exposure in the printing frame; it increases the sensitiveness of the paper and the vigour of the print. I have found dry plates comparatively insensitive when exposed immediately after drying them before a hot flat-iron. What is Major Russell's experience on this point? THOMAS SUTTON.

Questions and Suggestions.

MOUNTING.

fogged, but in the other the bars were sharply and clearly defined, and certain markings on the glass were also distinctly visible. There was no trace of blurring here. Is the effect rightly named? Did Mr. Leake speak of blurring? W. H. KENNEDY.

Transactions of Societies.

LIVERPOOL AMATEUR PHOTOGRAPHIC ASSO

CIATION.

THE ordinary monthly meeting of this association was held on Tuesday evening, the 26th instant, at the Free Public Library, William Brown-street, the president, the Rev. G. T. Banner, in the chair.

The minutes of the previous meeting having been read and confirmed, Mr. Forrest laid on the table a number of pictures, taken lately at Bettws-y-coed, upon plates prepared by the Liverpool Dry Plate Company, and stated that, out of the whole number he had exposed, he had not had a single failure. The development, he states, was effected by means of a weak ammonia solution, kept on the plate for a longer time than usual.

An animated discussion arose as to the relative advantages of weak and strong ammonia for developing, Mr. Mawdsley advocating a rather strong solution, and other members upholding the weak.

Mr. HUGHES said he had exposed a plate at Eaton Hall, the image upon which was perfectly visible before development.

Mr. MAWDSLEY said that it was a very frequent occurrence with over-exposed plates. He said he had noticed it in a marked degree upon a plate he had exposed for an interior, when the window was well out before developing.

Mr. GREEN remarked that since collodio-bromide had come into use very little was heard of comets.

Mr. MAWDSLEY said he had never with collodio-bromide met with a single instance of the old tannin spot round and transparent, with a black nucleus.

Mr. FORREST exhibited a piece of glass which had been exposed to light for over three years in a church window, part of it covered with paint, and pointed out the marked change which had taken place in the colour of the exposed portion, it having acquired a very decided pink tone. After explaining the cause of the change of colour, he touched upon the importance of having photographic lenses-especially those exposed to a concentrated light in enlarging-free from any cause of change of

colour.

Mr. HUGHES said he had a pair of portrait lenses by Ross, one of which had been much used for enlarging; but no change had taken place in that, as it worked as rapidly as the other, which had never served that purpose.

Mr. WHAMBY said the change of colour in lenses was generally attributed to the Canadian balsam used in cementing them.

The PRESIDENT said he had great pleasure in announcing that Mr. Green had offered two more of his large photographs to the society, to be disposed of as follows:-One to be presented by the society to Mr. Sayce, in recognition of his efforts in perfecting the collodio-bromide process; the other to be given as a prize for the best collection of twelve stereo pictures to be exhibited at the July meeting.

The cordial thanks of the meeting having been tendered to Mr. Green,

Mr. HUGHES made some remarks upon "Enlarging." He said he had brought all his apparatus with him, for the purpose of practically illustrating the enlargement of microscopic ob

BLURRING.

S.R,-In the plenitude of my ignorance, I venture humbly to ask, What is the difference between over-exposure and blurring? In Mr. Leake's paper, in your last, it seems to me that he speaks of over-exposure. In Mr. Dawson's article, in reply to Mr. Leake, he speaks of the "effect defective" in question as blurring. After reading both articles in my glass-room, I turned my lens up to the glass roof, and exposed the two halves of a long wet plate, giving one-half two, and the other about five, seconds' exposure. The latter half was greatly overdone,

was unable to do so. He, however, exhibited his apparatus, and explained the method of applying it, calling particular attention to the fact that the focussing was done upon the surface of a piece of white cardboard, instead of through ground glass.

A discussion arose upon the subject of ground glass, &c., for focussing; and Mr. Forrest promised to show at the next meeting a specimen of a style of dull glass, which he thought would be just the thing required for fine focussing.

A vote of thanks was passed to Mr. Hughes.

The second excursion was discussed, and it was decided to go to Llangollen on the 22nd of June; the president kindly inviting the members to dine with him on the occasion. The meeting was then adjourned.

On the evening of the 25th inst. the Hampstead Studio Club was duly inaugurated, at a very pleasant meeting, attended by representatives of painting, sculpture, literature, law, and photography. The time passed so swiftly that it was nearly midnight before the meeting was dissolved. The next meeting of the club will take place on Thursday evening, June 25th, at seven o'clock P.M. On that occasion some of the members will meet early in the afternoon, for a ramble out into the country, with their cameras and sketch-blocks, previous to the in-door meeting.

J. V. D.-The little town of Bakewell is within a short, pleasant walk of Haddon Hall, and, we are told, you may find very comfortable head-quarters, with moderate charges, at the Castle Inn. We should be very glad to see some of the results of your trip, and to receive your kindly promised account of it for our pages.

S. G.-A piece of emery-cake answers for roughening the edges of glass plates.

ROBIN HOOD.-Obtain a form, fill up, sign, and return with a copy of the photograph. The registration fee is one shilling.

A VERY LITTLE ONE.-The sp ts are due to air bubbles formed during immersion in the fixing bath.

JOSEPH JOHNS.-Letter forwarded as requested.

ANTI-HUMBUG.-" Somewhat too much of this." Our readers will think us terribly ill-natured if we express our o inion, in response to your appeal, honestly and fearlessly. So please pardon us, both for the non-insertion of your letter and for the non-expression of our opinion.

G. S. KINGSLEY.-Your machine is identical with that of Mr. Hanbury which was fully described in the photographic journals about five years ago. 2. The fulfilment of your promise will greatly oblige us.

PHOTO.-To boil your nitrate bath in an iron saucepan was a serious blunder.

W. F.-You are a little too impulsive. How was it possible that our pub. lishers could know you desired to continue a subscriber in the absence of proper instructions to that effect? Suppose the non-renewal of your subscription had been intentional instead of accidental, and we had continued to send the journal, and had presently sent you an account for what you had not ordered us to sed you-you would then have had good reason for your indignation. Your opinion of our illustrations reminds us of the old saying,"Different people, different 'pinions;

Some likes happles, some likes inguns."

R. W. C.-We do not know Mr. M'Lachlan's address.

W. FEARON.-The gentleman you name did not, and, so far as we know, never pretended to, discover the bleaching action of chloride of mercury (corrosive sublimate) on glass negatives or positives. It was discovered at least as far back as 1853, by Mr. Archer, and published by him in his treatise on "The Collodion Process on Glass." He recommends it for certain effects in glass positives; but he says farther, "The process does not stop here; the bleaching of the picture may be considered the first step towards rendering a feebly-developed picture a densely black negative for printing." This is done first by washing the partly bleached plate with weak hypo, and then with a strong solution. Also, he says, "The blackening can be effected by a weak solution of cyanide of potassium applied immediately after the bichloride.' So you see all is not new that seems new to some photographers.

L. READE.-Use bleached wax by preference, if pure, but it is often adulterated with spermaceti starch, mutton-suet, or stearine. Probably none of these substances, except starch, would unfit it for the purpose you propose, and possibly not even that substance in moderation. 2. 1ou are using too weak a bath for your bromised collodion. Make it sixty grains of nitrate to the ounce of water. Read carefully Major Russell's rticle in last number. In it he describes the best known method of obtaining full success. 3. Were we to advise, we should say do not adopt the lex talionis.

NE PLUS ULTRA.-Your letter is under consideration. We think enough, and more than enough, has been already said on the subject; but we may publish some extracts, if you will allow us to curtail the long dimensions of your dissertation.

R. C.-We may probably review the R. A. exhibition, but it will be from a purely photograph view-point.

A WEAKLY ONE.-The "Mesja" pocket photographic apparatus consists, according to a circular now before us, of a camera 4 i. long, 3 in. wide, and 8 in. deep, with lenses of 2, 3, and 4 in. focus, a plate-box, holding thirty glasses, 8 by 2 in., fits inside the camera, and when the latter is in use, fits upon the top, and is so arranged that plates can be lowered from it into the camera. The size of the diaphragm, it is stated, can be altered without removing it. We have not seen it.

MESJA. Received.

D. W.-We shall be glad to receive contributions from you. Journals sent. A VERY POOR PHOTOGRAPHER.-We think it probable that you may obtain what you require of Mr. Cox, 26, Ludgate-hill.

ROBERT MILLO.-Many thanks for your very beautiful photographs. Mr. Seymour is delighted with them.

G. W.-THE ILLUSTRATED PHOTOGRAPHER ought to have reached you just as early from the publication of the first or second number. The delay has not been with our publisher. We do not know whether Mr. J. Shearer's washing machine can be purchased or not, so cannot tell you where, nor at what price, it is sold.

BOTHERATION.-The cause appears to be dust. Keep your bath covered, your dark room clean, and y ur slides and camera in the same wholesome condition, and the spots will probably disappear.

COLOURIST.-Always do as much as you can with washes of colour before, you begin to hatch or stipple; you thus secure a body and richness which you are apt to miss by stippling up from too early a stage of progress.

CHEMICO. Mr. Peter le Neve Foster, Secretary of the Society of Arts, wrote a very careful and elaborate history of the metal aluminium, which you wil find published in that Society's Transactions. We cannot remember the exact time, but think it was in 1859.

JOSEPH J. WALL.-We shall be glad to hear from you.

C. L. B.-1. The term absolute, as applied to the alcohol usually sold, means liquids of the specific gravity of about 725 and 805 respectively. 2. The medals awarded by the Society in 1863 were distributed four years after by Sir Frederick Pollock, at the December meeting of the Society. They were designed by Mr. Durham, the sculptor. For further particulars, see journals of that date.

VICTOR G. SWEET. Mr. William Crooks, who had previously edited the Journal of the Photographic Society, and is now editor of the Chemical News.

SON BOB.-A collodion suitable for long exposures is kept by several manufacturers. See our advertisement pages.

ARTHUR G.-Received. Thanks.

W. H. K.-If you cover up the glass on the right hand of your sitters more in advance of them, and draw the top blind slightly back, the modelling and roundness of the heads, and relief of the features, will certainly be improved. We can offer no other suggestion. The photography is of a very high class. ERRATA. At p. 190, first column, line 34, for "I do not know their use." read, I do not know the technical term; and at p. 191, line 31, for "long distance" read short distance.

CAUTION. We have no knowledge of the person you mention beyond that supplied from the source named in your letter, and are the efore reluctant to publish anything which might be construed into an attack upon an indi vidual, on private rather than public grounds. At the same time we thank you for the information, and shall file your communication for future reference, should occasion render it necessary.

LONDON, JULY 3rd, 1868.

perceive, by a recent number of THE ILLUSTRATED PHOTOGRAPHER, that Major Russell states, that black varnish is as good as any of the substances since devised, except that What we

A SIMFLE AND CERTAIN REMEDY,

BY G. MARLOW.

ANNOT we begin to call this phenomenon by its right name ? Let us make a start without any further remarks on this point. I may be allowed to say that it is rather singular that the question of discovery and rediscovery, raised by Mr. Dawson, should have to be adverted to again. One would have thought that the matter had been so clearly stated during the last discussion, that it would not have to be done a second time. But I observe that Major Russell has written so clear a statement of facts, on page 174 of THE ILLUSTRATED PHOTOGRAPHER, as to render it un-necessary for me to reply to them here. I may state, however, that the heading of my first communication was as clear as it was possible to make it. The heading was, "Halation: its True Cause and Remedy."

During the last few years I have done little or nothing in photography, and have not, as a consequence, heen troubled with this disagreeable phenomenon, and I have not therefore employed any of the methods recently recommended to escape its effects. But observing the other week an article in another journal, by Mr. Lea, again recommending the use of dyes in the sensitive film, I once more determined to look into the matter, and see what could be done to avoid, as much as possible, any more complications in the now almost innumerable photographic processes, by perfecting a method recommended by myself seven years ago. I have before objected to the use of dyes in the film; it seems to me the last desperate resort. I do not object to experiments in any and every possible direc. tion, providing methods for accomplishing the object in view have been exhausted, which treat the defect in the simplest way, without complicating still more the already complicated photographic processes. The object in view in the introduction of dyes into the film is professedly to render it impervious to the active rays; theoretically this would have a tendency to keep the picture on the surface, instead of in the film. Besides, the thinner the film the greater the necessity for greater protection, while conditions would be such that the greater protection would not be possible, from the thinness of the films not being able to carry sufficient dye matter to prevent the penetrating rays from doing mischief on their return from the back reflecting surface.

It seems that Mr. Lea and others have observed that the different kinds of coloured pastes, &c., employed at the back of the glass, contract so, on drying, as to tear themselves from the glass and destroy optical contact. Of course this is no remedy at all; but supposing they did not separate themselves from the glass, would the colouring matter employed in such cases be in accordance with theory? I think not. The nature of the photographic film is different to what it was when iodide alone was used, which is very insensitive to yellow light. Now we use a bromide, either separately or in combination, which is sensitive to nearly all the colours of the spectrum. The present films have been looked upon in the same light as though nothing had been altered, and as if we still had films which are insensitive to yellow light. It seems useless to back the glass with a yellow substance when the film at the front is sensitive to yellow light. It is clear, then, that the backing should be black, as recommended by myself in my first communication on this subject. This is the view I have taken during the last few weeks, and I have conducted my experiments accordingly. I have endeavoured, in fact, to imitate the black varnish as first recommended, but at the same time avoid the difficulty of getting it off the back of the plate previous to development. I

Vol. I.-No. 22.

the very reason why I have not pressed its use. want, then, is a substance that shall not reflect any light at all-that shall remain in optical contact with the glass after desiccation, and that shall be easily removed without leaving any messes, or incurring chances of spoiling the sensitive film during removal, together with ease of application.

These properties I hoped to have secured in a mixture of some black pigment, such as gas-black with collodion. This pigment, added to collodion, which of itself adheres to glass perfectly, causes the film to separate itself from the glass in one sheet; but on the addition of a little castor-oil, this tendency to separate is avoided; the collodion is rendered short, very adhesive to the glass, and impervious to moisture employed to remove it from the glass when required. There is, however, a point-but it is a matter of great nicety-in which the oil may be so regulated as to allow the film to be separated from the glass when wetted. I found, during these experiments, that, with a given collodion, the more gas-black was added, in order to render the film opaque, the more oil was required to keep the collodion in optical contact.

These facts, I think, will show why paper pasted, and coloured pastes painted, on glass, separate on drying, and will also point to a remedy. An inquiry into the physical nature of this phenomenon is not without interest; and perhaps I may be allowed to indulge in an attempt at an explanation. We have paper, pastes, and powders; all of these are, more or less, rigid bodies, or are composed of rigid particles, which are required to be held together and to the glass by a soluble substance of some kind, such as gum arabic, glue, or pyroxyline. These, in parting with their solvents, contract, but adhere to the solid particles, which are completely surrounded, and which are held in their position, by the adhering material, from moving either to the right or to the left, or in any other direction. The contraction must consequently take place in one direction only, and that is vertical to the surface of the glass. This contraction will be in two directions in reference to the centre of the solid particles on the side next the glass, and the side away from the glass. Now, if these solid particles are of considerable size, and the adhesion between the glass and the adhesive material or medium is not very considerable, and the contraction of the latter great, the adhesive medium and the glass must separate, leaving the solid particles as so many supports from which a thin film is stretched, like so many tents all joined together, the supports or particles alone remaining in contact with the glass. It is evident that the larger the particles are, the more apt the adhesive substance will be to leave the glass, and vice versa; consequently with a given medium, the size of the particles may be such that, on the desiccation of the adhesive medium, the force of contraction shall be just under the force of attraction between the adhesive material and the glass. The ratio, between the solid particles and adhesive substance will influence the result. The same may be said of paper when pasted on glass. Thick or spongy paper will therefore require a thick or strong adhesive solution, and at the same time more elastic, so that the adhesion to the glass shall be in excess of the contracting force; at the same time sufficient must be employed to saturate the paper, so that that which is in contact with the glass shall not be drawn away by capillarity, to fill up the interstices of the paper. The elasticity of gum arabic is very small. Some material which has no tendency to become rigid when exposed to the atmosphere must be added to it, such as molasses, or, if this is not scientific enough, or too homely, glycerine will answer the purpose. It will be seen, then, what is required in order to keep paper and pastes in optical contact. It has been asserted to be impossible; but a few experiments, some years since, led me to think differently, and have been of considerable

manner.

service in enabling me to accomplish the object in view. A solution of gum arabic spread on glass, especially if strong, and allowed to dry, and more particularly if dried with heat, will crack, and finally separate itself from the glass in flakes. If molasses be added in the proportion of I gr. to 3 grs. of gum, this tendency is prevented, without making the resulting film tacky. I have already affirmed that a strong solution is required in order to fill up the interstices of the paper, and those between the paper and the glass, and to allow for contraction on desiccation. With a given sample of thin black paper, 3 drs. of gum arabic, and 1 dr. of molasses by weight (one drop from the end of a teaspoon weighs about 2 grs.), is the best I have yet tried. A weaker solution than this will not do for the kind of paper I have been experimenting with; it is the ordinary kind of tissue or cambric paper of the shops. If this is used as purchased, it must be applied in a particular The solution is easily made by pounding the gum fine, adding it to the water, and keeping it in agitation until dissolved. It should be allowed to stand some time before it is used, to enable all the air-bubbles to rise to the top, then carefully strained through cloth into another bottle for use. The prepared plate is to be placed in a carrier with corners of wire. This should be fixed in a slightly slanted position, and the solution, which should be raised in temperature above that of the atmosphere, to avoid condensation of vapour upon the plate from the atmosphere, poured on in a pool at the upper end; then by carefully moving the finger along the surface of the solution, it may be led all over the plate without bringing it up to the edges. The paper, which has been cut a little smaller than the plate, is to be applied by one of its ends to the end of the plate having the small excess of solution upon it, and gradually laid down; this will drive the excess of solution before it, which may be drained off from the end to which it is driven, then set aside to dry spontaneously, or by heat, if required. When dry, there will not be the slightest indication of separation from the glass. If wrinkled, the paper may be smoothed with an iron, but if it does not lie down smooth, do not attempt to force it down; the chances are, where it is touched, there will be a want of perfect optical contact. Let it dry without touching, if it is wrinkled, and all will be right, and tight, and smooth. The attraction and contraction of the various materials employed will do more, and that more will be done better than with the help of all the mechanical manoeuvring we can apply. Some will be tempted perhaps to get rid of air-bubbles, by pressing them out with the fingers. This cannot be done effectually; a portion of the air may be pressed out, but there very often remains a number of very small bubbles, which, when the gum becomes dry, increase in size considerably, being flattened out as the paper comes in closer contact with the glass, from the contraction of the gum. It is probable that with a stronger solution of gum, manipulation with the fingers might be allowed, and then, if pressure were applied, there would remain sufficient gum behind, so that when dry, optical contact would be secured. It very often occurs that, in our anxiety to gain an object, we employ means which are totally opposed to the attaining of that object, by trying to make the materials we employ do our bidding, instead of observing their properties, and adapting ourselves to them, and taking advantage of any peculiarities they may exhibit which will answer our purpose. There is probably nothing that will illustrate this principle better than the case in hand. Of course, the best recommendation for any method is actual trial. How will it answer in practice? A Norris's rapid dry plate, one-half backed, as here recommended, and the other half with a weaker gum solution, without molasses, proved beyond cavil the superiority of the former, or stronger solution, with molasses. The half which had the paper in optical contact rendered the shadows, in what was considered to be a picture very much overexposed, perfectly clear, and yet full of detail, hardly showing any signs of over-exposure, while the other side looked like a picture very much over-exposed, the details

obscured, and not a single clear shadow to be seen anywhere. Those who have not the time to prepare their own plates, or prefer to purchase them ready for use, will find Norris's rapid plates, backed as here recommended, all that could be desired. I may here say that I have tried various makes, but have never yet obtained any that equal then, either for sensitiveness or other good qualities. When properly treated, they are not only as sensitive, but present exactly the same surface bloom and general appearance as a wet collodion negative under its best conditions. I have communicated the formula and modus operandi to the firm, and have no doubt that, excellent as have been their plates for so many years, they will in the future be much improved, when a perfect system of backing, to prevent internal reflection, is adopted, which I am led to understand is now being done.

I have said nothing as yet concerning the removal of the paper from the back of the plate. This is so easily done, that I had almost forgotten to say anything about it. All that is required is to damp the paper with a sponge or piece of rag soaked in water. As soon as the paper is saturated, it can be stripped from the glass without endangering the sensitive film. It will perhaps be as well to reserve the washing off of the gum until the picture is finished.

Improvements in the above method will probably suggest themselves, such as floating the paper on a strong solution, and drying it. Paper so treated would not require so strong a solution, when it is applied to the glass, to keep it in optical contact. It will, of course, be easy to vary the method, or employ different materials other than those enumerated, when the principle I have been endeavouring to point out on which to apply them is once known.

REMARKS ON M. A. MARION'S NEW CARBON PROCESS.

BY WILLIAM BLAIR.

I Now propose, as indicated in a former article, to consider at more length the claims of this process, and how far the details given are improvements on the process some time ago published by myself.

The only account I have seen of this process is the letter by M. Marion, translated in an article by Mr. Sutton at page 117 of this journal.

The impression from the negative is taken on black gelatine tissue, sensitised in the usual way in a bath of bichromate of potash. It is then steeped in cold water, frequently changed, till the unaltered bichromate is got rid of, by which time the gelatine has swelled considerably and the impression is to some extent visible in relief. It is then laid on unsalted albumenised paper, which has been floated on its back to soften the albumen, and the two papers thus placed in contact are subjected to heavy pressure between glasses for an hour or more, after which they are allowed to dry. They are then subjected to hot steam in a hermetically-sealed vessel, till the albumen is coagulated, after which they are put into warm water, when the gelatine gradually melts, and the picture is left upon the albumenised sheet, where, M. Marion says," it is doubly unalterable upon its final support.'

In principle this is the same process that I published in the year 1864 (see Photographic Notes, vol. ix. p. 218), and considerably improved upon in 1867 (see vol. xii. p. 181, of same publication). In my first attempts with this process, I used albumen in its natural glutinous state (after beating up, of course) for transferring the impressed carbon sheet; but at the second period above mentioned, I adopted dry albumen, partially coagulated with alcohol, completing the coagulation ultimately in both cases by the use of hot water before washing up, or in course of doing so.

I am disposed to think that this process, in the state in which I left it, and now occasionally work it, is preferable