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containing chlorides. Chloride of silver is soluble to a certain extent in nitrate of silver, indeed to a greater extent than is generally imagined, if the nitrate solution is concentrated. Possibly this may be the impurity contained in Mr. M'Lachlan's nitrate of silver, which will take up as much as one per cent. of chloride.

Mr. SPILLER then read a short paper on the subject, which was taken from him by the chairman immediately after it was read. It merely explained the position in which he was placed by the absence of sufficiently definite information from Mr. M'Lachlan. He stated that he had certainly never met with that sudden precipitation of iodide, after an interval of a few days, of which Mr. M'Lachlan had spoken. Mr. M'Lachlan's theory of ozone was a very mysterious one, at variance with all chemical teaching and chemical facts.

Mr. HOOPER made some few remarks, in the course of which he said the subject before them could not very well be dealt with in the course of a short discussion. The harmonious adjustment of the working qualities of chemicals was, of course, very important. Acetic acid in the bath he had tried, and found it rendered it less active, and the plates less sensitive. Mr. M'Lachlan had failed in substantiating his theory, and he thought he might perhaps have avoided the three months' sunning, if he had served his bath as he did his developer, viz., boiled it. He did not agree with Mr. Fry in believing photographers met with few difficulties they could not overcome. Boiled bath was, he said, very good, indeed, better than new bath.

Mr. M'LACHLAN was then called upon to reply. He spoke of hundreds of distinguished photographers who had come to him bewildered and perplexed by failures they could not overcome; of the "thousands upon thousands of THOUSANDS of THOUSANDS" of experiments he had performed to attain the success he then enjoyed. Speaking of the acid added to the developer, he said he could not be responsible for erroneous statements promulgated by editors, and said Mr. G. Wharton Simpson had made him advocate, in his photographic journal, 3 ounces of acetic acid to the developer, instead of that number of drachms. He could not help these things, they made the "hair stand on his head!" He had made not less than "six thousand samples of gun-cotton and twenty thousand samples of collodion" before he arrived at the perfection his process placed within the reach of all photographers. He said streaks in the direction of the dip invariably arose from an excess of sulphuric acid introduced from the pyroxyline, that pure alcohol was slightly acid, that with 2 oz. of nitrate of silver he could sensitise four hundred half-plates! He said his bath was not neutral, but perfectly alkaline, and always gave clean, clear pictures, &c., &c., &c.

Mr. M'Lachlan was proceeding with increasing enthusiasm, when the chairman rose and courteously expressed his high sense of what the members owed to any gentlemen who, having patiently laboured for years at a series of important experiments, had then come honestly and generously forward to give them the benefit of such valuable experience. Mr. M'Lachlan had broken new ground in a very important way. He (Mr. Glaisher), fully agreed with him as to the importance of harmonising the working of the chemicals, and also in his idea of always preserving them all at one equal degree of temperature. At the observatory this was very stringently observed, the temperature being that of 60 degrees. He quite agreed with Mr. Fry as to the certainty and freedom of operating experienced by our best photographers, and instanced what he had seen in the studios of certain well-known operators. The meeting then adjourned.

NORTH LONDON PHOTOGRAPHIC ASSOCIATION.

THIS Society held its usual monthly meeting at Myddleton Hall, on Wednesday evening, May 6th, Mr. Simpson in the chair. The attendance was very thin, there being only nine or ten persons present, all included. What a falling off from its vigorous existence of four or five years ago, when the large room was often crowded with members, and the discussions on photographic subjects were generally carried on with unflagging spirit till a late hour!

Mr. Bockett read a very interesting paper on "The changes that have taken place in photographic chemicals and materials after a lengthened disuse." The short discussion that ensued was of a very desultory and conversational kind, some of the members, not excepting the chairman, wandering away from the real questions at issue. A digest of Mr. Bockett's paper, compie

hending the questions he put, will be found in another column, in an article by Mr. Dawson. These questions were not answered satisfactorily; and some of them could hardly have been so, unless he had produced samples of the chemicals and materials which he was describing.

Questions and Suggestions.

HAMPSTEAD STUDIO CLUB.

SIR,-A little time since I suggested the formation of a society such as that of the Naturalist's Field Club, to which I belong, for the purpose of holding out-door meetings. Can you inform me if any such feature is intended in connection with the proposed new Hampstead Studio Club ?-I am, &c., A NATURALIST AND PHOTOGRAapher.

[The club you mention is intended to promote social intercourse between artists and photographers. Its features will be out-door and in-door meetings, discussion, a little music, an exchange club between sketchers and photographers, pipes, &c. Every member will be expected to bring with him something of interest to each in-door meeting a folio of photographs, sketches, or prints, &c. The subscription will depend upon the cost of printing rules, and upon the cost of providing the secretary with stationery, &c. The preliminary meeting will be held on Monday evening, May 25th, at Weatherall Cottage, Well-road, Hampstead.-ED.]

THE POCKET CAMERA.

SIR,-I have read with much interest, in THe Illustrated PHOTOGRAPHER, an account of the satisfactory result of using a pocket-camera and dry plates.

I am a very old amateur photographer; my principal amusement now is taking views of Highland scenery, and as I have to carry with me a tent and half a cart-load of apparatus, to me a camera, such as is described by Mr. Sutton and other writers in your publication, would be an indescribable comfort.

As, however, I live far from London, and have no opportunity of my brothers in the "black art." So before investing in the of examining their new cameras, I must trust to the assistance purchase of a new apparatus, I shall feel deeply indebted to Mr. Sutton, or any other experienced photographer, who will kindly take the trouble of replying to the following queries:1 What is the price of a pocket-camera and lens with, say, six slides, and the walking-stick tripod ?

2. What maker is recommended?

3. Has it the power of giving the definition of a mountain at, say, a mile and a half distance?

4. What angle does the lens take ?-I am, &c.,

AN OLD AMATEUR.

Heplies and Discussions.

INVISIBLE PHOTOGRAPHS.

SIR,-I enclose a piece of paper, which at first sight you will probably take to be only dirty, but if you will look carefully you will find on it a sitting female figure. The circumstances under which it was produced were the following:-A clean glass plate was taken and coated with a solution of wax in ether; allowed to dry, and again polished. Then a positive was produced in the ordinary way in a copying camera, toned with bichloride of mercury, and fixed with hypo, then transferred to a piece of ordinary Rive paper. It was put in a drawer, having no further use for it, along with other experimental productions. A few days ago I happened to look into the drawer, and found it in the state in which I enclose it. Can you explain the strange change?—I am, &c.,

Newton Hill, Leeds.

J. CROSTHWAITE.

[The piece of apparently white paper enclosed by our correspondent did show, when examined in a strong light (transmitted) a very faint trace of an image. Suspecting the cause of the disappearance of the image, our very first experiment proved the truth of our surmise. The blank paper was immersed in hyposulphite of soda, when the image reappeared in full vigour, and a very good picture it was. The explanation of the phenomenon is the same as that for what were called the "magic photographs." A silver print (not toned in gold) is washed thoroughly, and immersed completely in a saturated solution of chloride of mercury (corrosive sublimate). The

image disappears, because its constituents have been changed into a white double salt of silver and mercury. To make the image reappear, it is only necessary to treat the white paper with any soluble sulphide or compound of sulphur, hyposulphite of soda being as energetic as any, and most readily applied. The image is now a visible sulphide, and not an invisible chloride.-ED.]

a

THE POCKET CAMERA.

SIR,-On reading your last number, I find you have quoted an
article from the Mechanics' Magazine of the previous week, having
reference to a pocket-camera and walking-stick tripod. As the
article in question no doubt refers to the small camera and tripod
I have introduced, I should feel obliged if you would rectify a
few errors respecting its size, &c. The writer of the article
proposes, in the first place, that it should be named the "satchel"
camera, not pocket, thinking no doubt that it is too large to be
carried in the pocket, which is not the case. So far as the name
is concerned, I think it matters little, as the camera in question
can be carried either in the pocket or "satchel," and is quite
independent of the double backs, which are as small as possible,
consistent with strength. I think, what would be preferable to
many than
satchel," is a black leather sling case, similar to
an opera-case, which would carry the camera, and three double
backs lengthways. Such a case would be of the following size,
viz., 9 by 5. The three double backs having six plates
in them, six others could be carried with ease in a small
metal box. Thus, with twelve plates to expose, the tourist
would find quite sufficient for one day's work. With regard to
the lens being an awkward object to carry in the pocket, I
would remind your readers that the kind of lens required for
use with this size of camera (such as Ross's doublet or stereo-
graphic) is so small, that it can be reversed and carried inside
the camera simply by unscrewing. The next objection is the
top of the stand. As there is no top required to my walking-
stick stand, that difficulty is got over. With regard to bolts
-and screws, there are none separate from the camera or stand,
therefore nothing to lose. The camera is supplied with a rack
adjustment, and the tailboard, which is hinged, is made rigid by
two flat brass bolts on the bottom. It has a bellows body, and
will focus up to 6 inches. I think the bellows-body camera
preferable to a rectangular box, as proposed, being much lighter
and more applicable to lenses of different focus, and certainly
less bulky. A box-camera cannot, in any case, be less than 24 in.
in depth, to suit a lens of the shortest focus, and therefore would
be quite an inch larger than the bellows one described above.
With regard to the rigidity of the stand, it will be found suffi-
cient for the size of camera for which it is intended. However, in
case a stand of stronger pretensions should be preferred, I have
provided one of about the size of an Alpine stick, on the prin-
ciple of those used with surveying instruments. With the addi-
tion of a sliding rod for adjusting the height of the camera, and
tightening screw, such a stand would be found perfectly rigid
in a high wind, as well as being a help to tourists. I do not
think intending purchasers of the pocket-camera will find
that efficiency is sacrificed for portability. The above camera
and stands are quite ready for sale at Messrs. Negretti and
Zambra's, 153, Fleet-street.-I am, &c.,

WASHING-MACHINE IMPROVEMENTS.

C. D. SMITH.

it is necessary to allow one of the arms attached to the ball to
have freedom to move in a socket, soldered on the side of the
ball. By regulating the small waste-pipe of the water-box, the
washing machines will perform their work with all the precision
of clock work.-I am, &c.,
JAMES SHIVAS.
Peterhead, May 11th.

P.S.-This plan is also applicable to two of the machines for the smaller prints. India-rubber tubing will be found very useful for connecting the machines with the ball-cocks.

SELF-ACTING WASHING MACHINES.

We have received, from Mr. Collier and Mr. Shivas letters, not
very conciliatory, respecting the origin of the ball-cock wash-
Personal
ing machine, lately described in these columns.
disputes possess but little interest for our readers, and tend
to embitter feelings of friendship which ought to exist between
such clever and generous inventors. For these reasons, and
lest our pages should become a battle-ground for questions
which might descend to mutual recrimination, we hold back
these letters. We feel sure neither Mr. Shivas nor Mr. Collier
will, after due reflection, regret our decision, but will rather
be thankful that we have spared them considerable annoyance.
Let them shake hands and be friends as of yore, and congratu
late each other on the fact, that between them they have con-
ferred a great boon on photographers. [See Mr. Dawson's
article, p. 179.-En.]

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Exceedingly fine, warm, and congenial weather has marked the past week; the wind gradually veered from the E. through S. to the S. W. quarter, and has remained in that position, with but slight deviation, ever since. This is generally understood to be a wet quarter; yet when reference is made to the above report, it will be seen that although the barometer with the change of wind commenced gradually falling, showing a diminution in pressure, still the humidity of the atmosphere was comparatively small, and diminishing daily, giving an assurance that fine weather would continue until the instrument began to mark another change.

The readings at present are still indicative of a continuance of the present fine weather. Humidity is decreasing; barometer rising to wind, steady, with seasonable temperature; and until some decided change is marked by the instrument, no change of any importance need be feared.

SIR,-Photographers in adopting the washing machines, which I lately described in your illustrated paper, may be unfortunately situated so that they have not sufficient pressure of water to cause the necessary boiling motion among the prints in the smaller vessel, and fill the larger one at the same time. This being the case with myself, I set to work and devised the following plan, which may be of use to some of your readers:Instead of the water flowing into both the vessels at one time it fills them in turn, and while the one is emptying and draining, the other is filling. My method of doing so is this-only one ball-cock box is required, which is placed beneath the smaller washing vessel, into which the syphon discharges the water. Attached to the inside of this box are two ball-cocks, We have much pleasure in announcing that the Rev. one of them reversed in position, so that when the vessel is F. T. Hardwich has signified his intention of becoming an empty of water, the weight of the ball shuts it; the other occasional contributor to our pages. The great "Nestor" of working in the ordinary way. The two arms of the ball-photography, whose elaborate manual has been, rather irretecocks are attached to the sides of one large ball, the weight of which shuts off the water effectually, as the ball, by floating, shuts the other cock. As the two arms of the ball-cocks, by being placed in contrary positions, work from different points,

Bits of Chat.

rently, although not inaptly, called the " Photographer's Bible," is so pleased with our efforts to disseminate photographic truth, that, if health permits, he will now and then give us a ring of the old and true metal.

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We have pleasure in calling the attention of our readers to the next annual exhibition and prize list of the Royal Cornwall Polytechnic Society. Medals and prizes of various kinds are awarded annually by this excellent society, for progress in various departments of the fine and mechanical arts, both to amateur and to professional followers. Photography takes rank with sculpture and painting in the list, and is divided, like the others, into two sections, one for amateurs, and the other for professional competition. The works are exhibited, and the collection usually proves very attractive. The following prizes are awarded in the professional section:-1. For the best landscape, a silver medal. 2. For the best portrait or group, a silver medal. 3. For the second best landscape, a bronze medal. 4. For the second best portrait or group, a bronze medal. In the amateur section we find no such special particulars. Exhibitors in both sections are informed that the prints must be untouched by hand. If vignetted, a full printed picture will have to be enclosed for the inspection of the judges. Competitors may exhibit pictures in each class, but no competitor can take more than one medal. No works intended for exhibition will be received after the 21st of September, 1868, and none such can be removed until it has closed. The society is not responsible for loss or injury. In the section devoted to professional artists, the following prizes are given:-1. For the best figure picture in oils, a silver medal. 2. For the best figure water-colour drawing, a silver medal. 3. For the best landscape in oils, a silver medal. 4. For the best landscape water-colour drawing, a silver medal. The society invites professional artists to forward their works to the exhibition, the carriage of which the society will pay. The Art Union of Cornwall have arranged to select their prizes from the pictures so exhibited. Artists intending to exhibit should apply to one of the acting hon. secs., Polytechnic Hall, Falmouth, for the special rules applicable to this section, and forms to be filled up by the exhibitor.

The Standard says:-" If, as a general fact, we admit that there is nothing new under the sun,' our readers may well be startled in these days by the idea of a photographic novelty. Indeed, it is difficult to say in what branch of art, science, trade, commerce, amusement, &c., photography does not play an important part. It brings with equal facility within the ken of tarry-at-home travellers the most inaccessible Alpine solitudes and the soft luxurious repose of Italian lakes. It renders the features of every celebrity of the hour, from Mr. Gladstone to King Theodore, familiar to the public eye; and every policeman carries in his pocket the pictures in little of the ticket-of-leave men who, by the amiable weakness of justice, are let loose upon his beat. Trade, however, has taken a hint from Scotland-yard. We have before us a circular stating that a certain individual, in a particular business, has commenced for himself, and enclosing a carte-de-visite of the enterprising tradesman; from which, he says, the ladies to whom he sends his circulars and his portraits will doubtless recognise him, on account of the active part he took in the business of,' &c. It need not be added that devotion to business,' and 'undeviating attention to the wants of customers,' are expressed in every feature of this interesting masterpiece of photographic art."

Mr. William Blair, of Perth, one of the great pioneers of carbon printing, has lately perfected a valuable new process, by which the transparency of the print is rendered unnecessary, and the manipulation greatly simplified. He has promised an article on this subject shortly in this Journal. The exposure does not require more than five minutes in sunshine. The specimens have no glaze, but all the depth and vigour of printing-ink; the whites are perfectly pure. This new carbon process is certainly a great step in advance; the proofs have the appearance of fine engravings, or drawings in sepia, and are highly artistic. It is a process which will please everyone of taste. It is carbon printing for the artist and the amateur,

The publication of the National Records of England and of Scotland, by Photozincography, will probably be completed in the course of the present year. It is proposed then to publish the fac-similes of National Records of Ireland. There is a steady demand for the fac-simile of Domesday Book; the sum of £3,556 has been expended in the publication, and at the end of February £1,938 had been received from the sale of copies, and the copies in store would produce £1,900, so that the sale will more than cover the cost of publication.

Mr. Ross recently constructed, for the Abyssinian expedition, a doublet lens, which may well be called "long range." The diameters of the combinations were three inches and a half, and the equivalent focus four feet. Its performance was perfect. He has also made another doublet, of the same focal length, for the Belgian Government, which has received the approbation of the Minister of War. The combinations of this monster lens are eight inches diameter! This talented optician is now at work upon the largest portrait lens ever made in England. It is for the Indian Government. The diameters of the components are ten inches! The glass of which it is being made is from Messrs. Chance, and was exhibited at the Paris Exhibition last year. There is just now, Mr. Ross says, an extraordinary demand for microscopes, and he cannot make them fast enough to meet the demand.

Lord Brougham was at his chateau at Cannes when the first introduction of the daguerreotype process took place there; and an accomplished neighbour proposed to take a view of the chateau, with a group of guests in the balcony. The artist explained the necessity of perfect immobility. He only asked that his lordship and friends would keep perfectly still "for five seconds;" and his lordship vehemently promised that he would not stir. He moved about too soon, however, and the consequence was a blur where Lord Brougham should be, and so stands the daguerreotype view to this hour.

The Athenæum says:-"In consequence probably of our recent remarks upon the want of good and moderately priced transcripts from famous engravings of great pictures, the producing of which we recommended to those photographers who now devote their energies to pirating copyright works, Mr. Tegg sends us a print, by Mr. F. Bacon, after Da Vinci's 'Last Supper.' We know nothing about the price of this print, and so cannot state whether it answers in that respect the public demand for a cheap copy of this grand work of art. As a specimen of the engraver's craft, it is far from being so satisfactory as photography could produce from a better originalsuch as Raphael Morghen's engraving would supply; but taking it as a whole, it is by no means the worst we have seen." There is something the reverse of a compliment to Mr. Tegg implied in this paragraph.

On Saturday evening, under the presidency of Sir Francis Grant, President of the Royal Academy, the 59th anni. versary festival of the Artists' Benevolent Fund was held at the Freemasons' Tavern. It was shown by the report that the sum of £28,689 has been distributed in relieving the widows and orphans of artists since the establishment of the charity. Fiftytwo widows received during the past year annuities amounting to £847. From its beginning, the charity has been one of the most economical established, and still maintains that character. The Chairman, in proposing the toast of the evening, "Prosperity to the Artists' Benevolent Fund," explained the nature and operations of the association, pointing out the great benefit that had resulted to artists from the institution. The society invited all young artists, by the payment of small subscriptions, but to establish a claim in the time of adversity. Artists were to come forward honourably and manfully, not to solicit charity, too often improvident, but they had, to a certain extent, an excuse for this revelling in imagination; they too often forgot the dictates of prudence, and the duty of making provision for the future. Since he had been president of the Artists' Benevolent Society, he had been struck with the high character of many of the works of young men who were now recipients of this charity, and he mentioned several cases of this sort of the most distressing character, among others, one who had painted some charming landscapes, and who for nine years had been an inmate of a workhouse. Another, who for some years had occupied a high position, and been in receipt of a large income from his profession, but who had become disabled by sickness, and had died, leaving his family wholly unprovided for. In these, and many other cases of a similar character, a society such as this would have afforded relief and timely assistance, and he earnestly appealed to the body of artists generally to give increased support to an association so well calculated to be of service to them in time of unforeseen difficulty. The subscription list-including 100 guineas from the Queen, 20 guineas from the chairman, and £10 10s. from Lord Hardinge -amounted to nearly £800.

At a recent meeting of the French Photographic Society, M. Blanc made a few remarks on the development of dry plates. He said it might be laid down as a general principle that the development of the lights of a picture is prejudicial to the development of the half-tones, unless the lights have been somewhat over-exposed. For this reason, with two exposures of equal duration, more detail is obtained in the shadows when the sun is obscured than is secured when with full sunlight, and that by alkaline development shorter exposure may be given than by the ordinary method; the silver which forms the image being decomposed, and unable, therefore, to exercise its affinity for the lights of the picture. For the same reason he thought it necessary to allow the lights of a picture to become solarised, so that their great affinity for reduced silver might be weakened, and stated that a slow development was required for subjects presenting much contrast. With reference to slow development, M. Blanc communicated a method which he believed was not generally known, viz., that of placing a dry plate in a very dilute alcoholic solution of pyrogallic acid containing no nitrate of silver or alkali of any kind, whereby an image may be gradually but very effectively developed. He thought that the silver percipitated in this case was probably due to a trace of nitrate of silver still resident in the plate, which a washing of even the most careful description may have failed to remove; decomposition taking place at once, the activity of the lights will not prejudice the development of the half-tones, and hence a very gradual result, similar to that obtained by alkaline development. The mode of proceeding is a very slow one, fourand-twenty hours being scarcely sufficient for its completion; but what is lost in rapidity is gained in power, and it is in this direction M. Blanc thinks that photographers desirous of securing rapidity of action in dry-plate photography should direct their attention, for the purpose of discovering some new developer. In chemistry the most feeble affinities produce great effects, if the necessary time is allowed for their action. And what is the development of a negative but a chemical action? An exposure of the most rapid description suffices to secure a feeble impression, and to create, therefore, a feeble affinity for the reduced silver. By giving more time to the operation of development, varying its details, and employing new materials, the desired result might possibly be attained.

W. M. Gardner describes, in the Philadelphia Photographer, the following method of enlarging on canvas. To prepare the canvas, rub it with pulverised pumice-stone. Then make a paste of China clay and water, and coat it. When dry, wash off, and, while wet, pour on a solution of 50 grains of bromide of potassium, 10 grains of water, 5 grains of cyanide of potassium, and set it aside to dry. When dry, silver it with a solution of 30 grains of nitrate of silver, 1 ounce of water, ounce of acetic acid No. 8, and print while wet. Fix in a weak solution of hyposulphite of soda. This process is for solar camera printing; or, if wanted to print by contact, prepare the canvas the same way. Salt the same as plain paper, and silver it with a 40-grain silver solution, and tone and fix as usual.

The mechanical aids which a master can communicate are of little importance. Sound principles are to be acquired by the study of fine works only, and the contemplation of nature.-Sir Martin Archer Shee, P.R.A.

NOTICE.-Full price will be given for copies of No. 4 of THE ILLUSTRATED PHOTOGRAPHER, to make up sets of back numbers, for which there is a steadily increasing demand.

To Correspondents.

alkaline state in the stock-bottle. This accounts for the gilding of the bottle. although kept in the dark. If acid solution of chloride of gold-and that salt as sold to photographers is always acid-is kept in the dark, there is little chance of its being decomposed. Of course your solution is now weaker to the extent of the equivalent of gold deposited.

EL DORADO.-You should not keep your solution of chloride of gold in an

SUBSCRIBER. We have received no explanation from the trustees, else we should have published it. We do not know whether you can claim the balance of your money subscribed. Consult a solicitor if you think the matter worth while.

ALPHA. You have arrived at too hasty a conclusion. From the sample of negative enclosed-which, by the way, was broken into small fragmentsthe developer.

your nitrat bath is evidently too acid, or you have been using nitric acid in

F. W. SHEPHERD.-The back numbers of this Journal have been forwarded to you, as directed, from which you will see that the apparatus for landscape photography, described by Mr. Sutton, is now manufactured by Negretti and Zambra. We cannot inform you as to the price. A note addressed to that

firm will, no doubt, elicit a reply.

ing the collodion film on the glass, provided the collodion is of average quality. From what you state, it appears probable you have been immersing the plate into the nitrate bath too soon after coating it. Try the effect of allowing the film to set a little longer before immersion.

JACQUES JEAN.-There is no difficulty whatever. in the wet process, of keep

J. T. C., Camberwell, who was formerly an assistant o Mr. Lake P ice's, and who has applied at that gentleman's former address, is anxious to learn his present abode.

W. MARTIN.-Mr. Belton, 13, Cliften-villas, Camden-square, London, will do the work for you, or get it done, in a very superior manner. You may rely upon him.

THE MANAGER. You can see the Collier washing machine any forenoon at King's College. Mr. Dawson says he will be glad to show it, and its admir able mode of working, practically to anyone who chooses to call for that purpose. You will see from Mr. Shearer's letter and diagrams in our last, that he has abandoned the ball cock system, and introduced probably a better plan, as it does not require a strong pressure of water, which cannot be always had in London. There is now no necessity for publishing your second letter, as, we daresay, you are now aware.

HAMPSTEAD STUDIO CLUB.-Several corresponden's are referred to this

week's "Questions and Suggestions" for an account of the purposes this pro

posed club is intended to serve.

"A Photographer among the Picture Exhibitions" will shortly appear. J. C. H.-The photographs are excellent. Posin, lighting, and choice of accessories all good. We should suppose there is every chance in favour of your success as a professiona' photographer, if as an amateu you can produce such charm ng works.

A DELIGHTED READER.-See pages 121-2. Thanks.

D. R. C.-1. If the engraving has been published more than twenty-eight years, you may copy it without fearf legal consequences. 2. By refe ence to a collection in cur possession, we find that the specimen from which the publication line has been cut away, was published in 1792. We think copi s of it woul seil. 3. Engravings by Jacob Adam are quite old enough. That of the Nymph Sleeping" was publishe 1 in 1788. The engravings of Francesco

E. B. FENNESSY.-We have to thank our valued contributor for some excellent photographs of jewellery, which reached us last week, bu with t any explanation or statement having reference to hem. Article on Pump for Photogra hers to hand. Thanks. W. H. KENNEDY.-Your request shall rece ve attention. Many thanks. PETER PLUCK's amusing letter should have appeared under the head "Replies

and Discussions."

An indelible marking ink is prepared from aniline by Albano are quite deserving your a te tion, if you can rocure them. mixing the two following solutions a, cupreous solution-8.52 grm. of crystallised chloride of copper, 10-65 grm. chlorate of soda, and 5.35 grm. of chloride of ammonium are dissolved in 60 grm. of distilled water; b, aniline solution-20 grm. of hydrochlorate of aniline are dissolved in 30 grm. of distilled water, and 20 grm. of a solution of gum arabic (1 of gum to 2 of water), with 10 grm. of glycerine, are added. By mixing in the cold four parts of the aniline solution with one part of the cupreous solution, a green liquid is obtained which can be used immediately for tracing characters upon linen; the marks, however, alter after the lapse of a few days. It is necessary to keep the solutions separate until required for use. If the fluid does not flow easily from the pen, it may be diluted without fear of diminishing the intensity of the tint, which, at first green, gradually darkens and becomes black. Heat causes the change to take place instantaneously; a steam heat is sufficient, and is better for the fabric than a hot iron. Afterwards the linen is washed in warm soap and water. This ink resists acids and alkalies, and is remarkably permanent.-Chemical News.

TREVELYAN.-1. We have heard the collodion in question both cole nnel and praised, but having had no personal experience with it, we cannot advise you. Give it a trial, the cost will not be very heavy. 2. See our advertise

In art nothing can be justly termed knowledge but that which we have made our own by observation and experiment.-Sir Martin Archer Shee, P.R.A.

ment columns.

NORTHERN LIGHT.-Your glass house, with the light proper'y controlled, should make a first-rate one, if the direction as to the cardinal points of the compass is crect. Your letter is not sufficiently ex lic t on several matters for us to give reliable advice on the proper "blinding." Please write us again, statin the direction of the length of the house, and whether you have got lights on each side. With these two essential pieces of information we can advis you more confidently. We have placed the xcellent photographs by Mr. Parry, which you kindly forwarde 1, in the hands of Mr. Seymour, who will no doubt us some of them for his sketches o: posing. Many thanks.

ARTHUR G.-The great principles in lighting, so as to secure good art sti modelling, brilliancy, and relief, are to keep all prominent surfaces light, ll retiring surfa es in half-tone, and to take care that both the highest lights and the deepest shadows belong to the figure, ani are ot to be found in the background,

MESJA. Received. Thanks.

RECEIVED, "An Indignant Member," "Jaspe Spink," and J. Gunny.

LONDON, MAY 22nd, 1868.

Transactions; although, it appears, the editor of a rival publication to their own, and who is also a member of council, contrived to get a copy in spite of a law which he,

A FEW PARTING REMARKS ON MR. M‘LACHLAN'S of all men, ought to have respected."

DISCOVERY.

BY GEORGE DAWSON, M.A., LECTURER ON PHOTOGRAPHY,
KING'S COLLEGE.

HEN I commented, a few weeks ago, with some severity, on Mr. M'Lachlan's verbal statement made at a meeting of the Photographic Society of London, I had some very slight doubt whether I might not have mistaken his meaning. He has now read the details of his "discovery" before that body, from a long paper, which, in a slightly rehabilitated form, fills nearly one-half of their journal. If I was considerably bewildered and astonished by reading a report of his verbal statement, I was still more so on hearing and reading his written one. He professes to revolutionise photography. So far he is right, but it would be the wrong sort of revolution. It would be from some sort of order, which we now possess, to chaos and general confusion. If I may be allowed to express my own private opinion, I should characterise his paper as the most extraordinary tissue of photographic nonsense that it has ever been my pain to read.

I am glad you have determined not to publish this long rigmarole of the false assumption and erroneous conclusions which are contained in it from beginning to end. To publish it would be a waste of space, and an insult to the judgment and common sense of your readers. Having read the lengthy document carefully, I think I can safely say there is not a single sound photographic fact contained in it throughout. All is bewildering confusion to the reader, and misconception on the part of Mr. M'Lachlana veritable, radical revolution indeed!

I have been accused, by a few, of having, in my previous article, dealt too harshly with Mr. M'Lachlan, and probably misunderstood him. With his own published statement before me, I feel quite relieved from any anxiety on that score, and I cannot conceive how it is possible for anyone endowed with common photographic sense to treat such arrant quackery seriously. I, for one, could not condescend to do so, nor indeed should I have taken any notice of his "discovery" at all, had not its birth been heralded by so many portentous omens, and its importance so belauded in the photographic journals and elsewhere, by credulous or incapable editors. I would therefore advise photographers not to be deceived, and tempted into wasting time and money in carrying out Mr. M'Lachlan's impracticable olla podrida recommendations.

make an

But I do not blame Mr. M'Lachlan, because he is well known as a good photographer, and an extraordinary enthusiast in any matter which he takes up. He is also, I believe, thoroughly honest and disinterested in his intentions. Therefore, I feel sure, in his recent attempt to mislead others, he has first deceived himself. What a pity, for his own sake, he did not display a little more judgment, or take counsel from his friend Dr. Angus Smith! I lay all the blame on the managers of the Photographic Society of London, for having encouraged and urged him on to "exhibition" of himself before the members, without due knowledge of what he wished to speak or write about. Surely after the "exhibition" of the previous month, they ought not, for their own credit, to have repeated the experiment. By doing so, this society has still farther lowered its already low position in the eyes of all sensible and scientific photographers. Before finally parting with this very ill-advised and foolish outery of a new "discovery," I have a few remarks to make on the short paper read by Mr. Spiller in the course of the discussion (see report of Photographic Society, p. 180). That paper was handed to the chairman, so that I could not, according to one of the laws of the society, have access to it, till it was presented in their own

Vol. I.-No. 16.

Mr. Spiller, after referring to the description given him some time ago by Mr. M'Lachlan, of the proper sort of silver to use for his process, says::

My grounds for believing in the possible occurrence of chlorine were, first, the description given of a special quality of nitrate of silver, which is sometimes to be met with in the form be rejected by photographers, but now is to be preferred. of "moist and dirty-looking crystals," such as would ordinarily Secondly, that chlorides are amongst the most commonly occurring impurities in water, and are almost invariably contained in commercial qualities of nitric acid, so that in the preparation of nitrate of silver from an inferior acid, and the use of anything but the purest description of distilled water, there would be some probability of chloride of silver being intermixed with the nitrate, and forming a combination which is affected by exposure to light.

I have since made direct experiments on this point, and find that chloride of silver is much more soluble in the nitrate than sample of crystallised nitrate containing one per cent. of chlorI exhibit a my previous experience led me to anticipate. ide of silver in intimate union, if not, indeed, in direct chemical combination. Such a product must always be in the form of small crystals, and unless special precautions are adopted, would invariably be discoloured by light. I made it by dissolving 117 grain of rock-salt (pure chloride of sodium) in a smalí quantity of water, and adding 340 grs. of pure crystallised nitrate of silver. The precipitate at first formed soon became redissolved upon warming and consequent evaporation of the water, the chloride of silver being to a certain extent soluble in of crystallising with it. A special experiment to decide the a strong solution of nitrate, and apparently having the power solution of the nitrate showed that it was possible to dissolve as extreme limit of solubility of the chloride in a warm saturated much as 47 parts of Ag Cl in 100 of the nitrate. A compound containing this high proportion of chloride cannot, however, be manipulated, for, on adding a mere trace of water, the white curdy precipitate begins to appear. The fact of such a combination being established lends support to the opinion I have hazarded respecting the chemical quality of the silver crystals employed by Mr. M'Lachlan. I do not, however, mean to assert that his black-looking article contains more than a trace of the chloride; but the presence of this body, even in small amount, of so delicate a chemical preparation as the nitrate bath. must be allowed to have great influence in altering the properties

For the last three years I have experimented a good deal on the solubility of the haloid silver salts in nitrate of silver, with the object of devising preventatives against the formation of pin-holes in the collodion film, and many of my earlier experiments were published. All intelligent photographers know that the nitrate dissolves iodide of silver in proportions varying with the concentration of the former. So also does the nitrate dissolve any of the haloid salts of silver. It is also well known to chemists, but not so familiar to photographers-although to their annoyance they must often stumble on the fact from seeing pin-holes in the collodion film-that double salts of nitro-cyanide, nitro-iodide, nitro-chloride, &c., of silver, can, by careful management, be crystallised out in abundance from solutions of these haloid salts in nitrate of silver. They all crystallise very much alike, that is, in long, transparent, needle-shaped crystals. On this subject consult Major Russell's excellent article at p. 161.

Mr. Spiller is wrong in asserting that crystals of nitrate of silver containing chloride or any other haloid silver salt in solution, or rather in chemical combination, must necessarily get discoloured by exposure to light. The truth is, they are quite as little influenced by light as pure nitrate itself; and if he had tried the experiment, he would not have made such an assertion. In my experiments referred to above, I have often crystallised down the strong nitrate solution saturated, or nearly so, with a haloid silver salt, but without allowing the double salts to form separately. The resulting crystals were slightly different in shape from those of pure nitrate. That was all. They were not in

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