Digitized by the Internet Archive in 2014 https://archive.org/details/photogenicmanipuOOfish_0 9 MANIPULATIONS IN THE SCIENTIFIC ARTS. PART III. PHOTOGENIC MANIPULATION. PHOTOGENIC MANIPULATION : CONTAINING THE THEORY AND PLAIN INSTRUCTIONS IN THE ART OF PHOTOGRAPHY, OR THE PRODUCTION OF PICTURES THROUGH THE AGENCY OF LIGHT : INCLUDING CALOTYPE, \ CHROMATYPE, CHRYSOTYPE, \ ENERGIATYPE, CYANOTYPE, ] ANTHOTYPE, AND AMPHITYPE. BY GEORGE THOMAS FISHER, Jun. ASSISTANT IN THE LABORATORY OF THE LONDON INSTITUTION. FROM THE SECOND LONDON EDITION, PHILADELPHIA: CAREY AND HART. 1845. PREFACE. The First Edition of this little manual has been for a con- siderable time exhausted, and although constant demands have been made for it, — a circumstance only to be attributed to the interest of the subject, — it was determined, that although more time would necessarily be consumed in the compilation, every exertion should be made to render the Second Edition as com- plete a record as possible of the numerous processes of the interesting- science on which it treats. In preparing the materials for the new Edition, it was found that it would be impossible to give within the necessary limits even a brief outline of many of the n)ost interesting processes and phenomena connected with this science, to which, at the last meeting of the British Association, the term Actino- Che- mistry has been given. Rather, therefore, than abridge or omit, and thus render the manual imperfect, it was determined to divide the work into Two Parts, the first portion being devoted to the consideration of all the photographic processes as applied to paper, and the second part being descriptive of the Daguerreotype, Thermography, Electrical and Galvanic Im- pressions. We trust that it may not be deemed out of place, if we venture to make a few remarks on the value of the discoveries recorded in this little work. Many persons are still disposed to doubt their utility, and to ask, on all occasions, the question, cui bono ? Independently of the extent to which we are jus- tified in anticipating that it will spread, and the advantage which may accrue from future discoveries, even now its great value is, we believe, manifest. All men of reading desire to possess faithful representations of the monuments of antiquity — the Pyramids of Gizeh, the palaces or the temples of Ancient Greece and Rome. Every one must feel a pure and healthful pleasure in contemplating the representations of scenes made sacred to our memory by the deeds of heroes, or the words of sages. The temples of Athens, the wonderful Acropolis, the mysterious ruins of Pssstum, and the fanes and o^rches of Rome, 1* vi PREFACE. proudly but vainly named the eternal, speak even from their pictures. Theirs is the still small voice of the past speaking of the mutability of all things to the present. The lesson they thus g-ive us, even those who have never crossed the sea which washes our island home, is but little inferior to that which the traveller receives who contemplates the moral of a crumbling arch or a broken column, on the very spots where once they stood the glory of the age. Even in our own land we have temples which realize, in their consistent and beautifully elabo- rate architectural details, the poet's fancy of a " petrified religion." We have monastic piles hastening to decay, but beautiful even in their dissolution, and baronial halls whose battlemented walls are tangled with the ivy and clothed with the moss of centuries ; and these are hallowed by holy recollec- tions which cling like the poetry of a pious superstition to every heart ; and they cannot pass away until we have forgotten the history of our own land. Each and all of these we are now enabled to preserve in the strictest fidelity. Every stone will tell its own tale : and as the mind of the poet shines for ever from his productions, so the very genius, the very spirit of the place, may now be impressed by the subtle fingers of light upon tablets of metal or sheets of paper, to speak to future ages as they speak to us. Again, by this wondrous science, we are now enabled to preserve and hand down to future generations the truth-telling portraits of our statesmen, our heroes, our philosophers, our poets, and our friends, with "all the mind, the music breathing through the face." But, independently of this practical utility, we have derived another advantage from the discoveries which have been made in this branch of science. We have been enabled to perceive and contemplate the beauty and harmony of those laws by which Divine Wisdom regulates and governs the universe. The}^ have shown us that not a sunbeam can fall without pro- ducing a molecular or chemical change. They have taught us how close is the tie which exists between all the imponderables, light, heat, electricity, &c. They have proved to us how necessary to organic life, to the germination and growth of plants, the vitality and welfare of the animal creation, is that efflux divine," of which it has been poetically and truly said that " balm, and joy, and life is in its ray." George Thomas Fisiieu. London Institution^ Feb. 1845. CONTENTS. I. — Introductory Remarks : page. Object of the Author - - - - 1 1 Definition of Photography - - - 11 Brief History of the Science - - - 1.^ Principle on which the Art depends - - 13 II. — Apparatus and Materials : Paper - - - - - - 17 Brushes - - - - - 18 Distilled Water - . - . - 19 Blotting Paper - .... 20 Nitrate of Silver - - - - - 21 III. — Different Methods of preparing the Paper : Preparation of the Paper . - - 21 Cooper's Method - - - - - 22 Daguerre's Method . . - - 23 Bromide Paper - - - - - 23 Great caution necessary in preparing the Paper 23 IV. — Photogenic Drawing, and its Application : To make the Drawings - - - - 25 The Objects best delineated ... 26 To fix the Drawings - - - - 26 Application of the Photogenic Art - - 28 V. ~THE CAMERA : Description of the Photogenic Camera - - 29 The Lenses ----- 34 VI. —CALOTYPE : Apparatus and Materials required - - - 37 Preparation of the Iodized Paper - - 37 viii COxNTENTS. Preparation of the Paper for the Camera - - 38 Exposure in the Camera - . - 40 Time of Exposure - - - - - 40 Bring-ing- out the Picture - . - 40 The Fixing Process - - - - 41 Remarks on the Calotype Art - - - 42 VII. —POSITIVE CALOTYPE: Mr. Grove's Process - - - - 45 Mr. Talbot's Application ... 46 VIII. — CHRYSOTYPE : Its Discoverer - - - - - 47 Definition of the term - - - - 47 Description of the Process - - - - 47 IX. — CYANOTYPE : Its Discoverer ----- 47 Description of the Process - - - - 48 X. —ENERGIATYPE : Description of the Process - - - 49 XI. — CHROM ATYPE : Description of the Process - - - - 50 XII. — ANTHOTYPE: Definition of the term - - . - 52 Description of the Process - - - - 52 XIII— AMPHITYPE : Its Discoverer - - - - 53 Description of the Process - - - - 54 XIV.— Concluding Observations - - 57 PHOTOGENIC MANIPULATION. I. INTRODUCTORY REMARKS. 1. It is not the intention of the author of this little treatise to enter into a philosophical detail of the laws on which the wondrous art of Photography is based, but rather to explain, clearly and distinctly, the various steps necessary to be taken by the experimenter in order to insure success, dwelling more particularly on those minor points which so materially affect the result of all experiments, and without attention to which failure will be the inevitable result. The work is %vrittcn solely for the instruction of the amateur, and is therefore divested as much as possible of all techni- calities, while at the same time care has been taken to recommend only those processes which are the most likely to be attended with success. 2. Photography,* or as it is also termed, photo- genicf drawing, is, as its name indicates, the art of producing pictures by the agency of light, and may undoubtedly be ranked amongst the most pleasing and curious results of chemical philosophy, nor is it the least useful. Every one who has seen the pretty phi- losophical toy, the camera obscura, must needs have admired the minutely perfect reflection of the landscape * From (pw; light, and ypapw to write, to depict, t From (pMs light, and yei'^aao to produce. 10 PHOTOGENIC MANIPULATION. or any other object brought within its view, although this admiration must have been accompanied by a feeling of regret that it was only a shadow doomed but to last for a moment. Photography, however, and especially those modifications of it which we shall hereafter have to describe, the Calotype and Daguer- reotype, enable us to fix " the fleeting shadows as they pass," and to render permanent the pictures thus deli- neated by the magic pencil of light. To accomplish this end, no tedious or troublesome process is required ; unlike the creations of the painter's art, the picture is not the result of long and tiring manipulation. In a moment all our work is done, our desires are fully accomplished. 3. Photography is an art of but recent date. True it is that it has been asserted, we fear upon questionable authority, that the jugglers of India were for many ages in possession of a secret by which they were en- abled, in a brief space, to copy the profile of any indivi- dual by light. Be this, however, as it may, it is certain that they have now lost all record of the art. Passing over this mere legend, we find that the effects of the sun's rays upon metallic compounds were really noticed by the alchemists, and in many old w^orks the folio wing experiment is given : — "Dissolve chalk in aquafortis to the consistence of milk, and add to it a strong solution of silver ; keep this liquor in a glass decanter well stopped ; then cutting out from a paper- the letters you would have appear, paste it on the decanter, and lay it in the sun's rays in such a manner that the rays may pass through the spaces cutout of the paper and fall on the surface of the liquor ; the part of the glass through which the rays pass will be turned black, whil(^hat under -ffie INTRODUCTORY REMARKS. 11 paper remains white ; but particular care must be taken that the bottle be not moved during the operation." This experiment, though so vaguely expressed, and so doubtful of success, that it was probably more fre- quently reprinted than repeated, is nevertheless the first certain record of the art we are about to describe. But although the alchemists had by this experiment actually stumbled upon the threshold of the discovery of Photography, yet so intent were they upon their fa- vourite search after the philosopher's stone, that every thing which did not promise them a result now deemed so hopeless was thrown aside as of no value. 4. In 1556, it was observed that a combination of chlorine and silver, called, from its appearance, horn silver, was blackened by exposure to the sun's rays. This was the first step towards the discovery of the photogenic art, beyond which no further progress was naade until, in the early part of the eighteenth century, Scheele, of Stralsund, discovered that this change of colour in the silver compound was produced by the blue rays, little or no effect being produced by red or yellow light. In the latter part of the last century, Mrs. Fulhame, in her "Essay on Combustion," published an experiment by which a change of colour was ef- fected in the chloride of gold by the agency of light ; and she added, that letters or words might be written in this way. 5. The first person who seems to have had any notion of Photography, as an art, was Mr. Wedgwood, who, in the year 1802, recorded an experiment in the Journal of the Royal Institution, to which his mind had been directed by observing that light blackened a solution of nitrate of silver, or, as it is more usually called, lunar caustic. The experiment of Mr. Wedg- 12 PHOTOGENIC MANIPULATION. wood was as follows : — A piece of paper, or other con- venient material, was placed on a frame and sponged over with a solution of nitrate of silver; it was then placed behind a painting on glass, and the light tra- versing the painting produced a kind of copy upon the prepared paper, those parts in which the rays were least intercepted being of the darkest hues. Here, however, terminated the experiment; for although both Mr. Wedgwood and Sir Humphry Davy experimented carefully, for the purpose of endeavouring to fix the drawings thus obtained, yet the object could not be accomplished, and the whole ended in failure. 6. It cannot then be a matter of wonder, that, after the failure of such men as Davy and Wedgwood, the subject should have been dropped for some time. In- deed, the art slumbered until 1814, when Mr. Niepce, of Chalons on the Soane, appears to have directed his attention to the production of pictures by light. He pursued his experiments on the subject alone for ten years, when chance having made him acquainted with Daguerre, they agreed conjointly to pursue the subject. In 1827, Niepce presented a paper to the Royal Society of London, on his method of taking pictures by means of light, naming his discovery Heliography ;* but as he kept his process a secret, it could not, agreeably to one of their laws, be printed by them. The memoir was accompanied by several designs on glass, on copper plated with silver, and on well planished tin plate. Daguerre had at the same time produced some specimens on paper saturated with chloride of silver; but the want of sensibility in the preparation had necessarily rendered them ex- tremely confused. * From HXfo; the sun, and ypa^w (o depict, to draw. INTPvODUCTORY REMARKS. 13 7. On the 81st of January, 1839, Mr. Fox Talbot communicated to the Royal Society his photographic discoveries ;^ and six months afterwards, the French philosophers published to the world, their process, termed Daguerreotype. Mr. Talbot's most recent discovery, the Calotype, was accidental. He was trying some experiments on the relative sensitiveness of several kinds of paper, by exposing them for very short periods in the camera ; some papers which were taken from the instrument, exhibiting no impressions, were thrown aside as useless, and remained in a dark room ; after some time, they fell again under his eye, and, strange to say, by a process of natural magic, pictures of the objects to which the camera had been pointed were found on them. 8. Previously, however, to the secret discovered by Daguerre and Niepce having been published, it was offered to the French Government, which entered into arrangements with them, by which they undertook to make public. their discovery, on the receipt of an an- nuity of 250Z. to Daguerre, and 166/. to Niepce. In the former case, this annuity has been increased to 446/. From this time the progress of the photographic art has been rapid, and the improvements in it mani- fold, owing to the continued exertions of Herschel, Talbot, Hunt, and others. Having thus briefly considered the history of this important and pleasing science, we will proceed in the next place, to consider the principle on which the art depends. 9. Light acts upon all bodies. To the existence of * Published in the London and Edinburgh Philosophical Maga- zine, vol. xiv. p. 126. 2 14 PHOTOGENIC MANIPULATION. this subtle agent alone do we owe our sense of all the varied beauties which are around us. Efflux divine! — Nature's resplendent robe! Without whose vesting beauty all were wrapt In unessential gloom." Light is the garb of nature, clothing the garden and the meadow, glowing in the ruby and the enaerald, sparkling in the diamond, and decking with varied tints the entire animal and vegetable creation. 10. But if its effects be thus visible throughout the organic world, equally apparent and equally wonder- ful are they upon inorganized matter.^ In some instances we may observe that the action of light will induce the combination of bodies, while in others it will effect their decomposition. Thus, chlorine and hydrogen will remain in a glass vessel without altera- tion, if kept in the dark; while, on the contrary, if exposed to the rays of the sun, they enter into combi- nation, and form hydrochloric acid. On the other hand, if colourless nitric acid be exposed to the sun's rays, it becomes yellow, then changes to red, and oxygen is liberated by the partial decomposition effected by the solar rays. 11. But of the inorganic substances none are more readily acted upon by light than the various combina- tions of silver. Of these, some are more and others less sensitive. If chloride of silver, which is a white precipitate formed by adding chloride of sodhim (com- mon salt) to solution of nitrate of silver, be exposed to diffused daylight, it speedily assumes a violet tint, and ultimately becomes nearly black. With iodide of silver, bromide of silver, ammonio-nitrate of silver, and other salts of this metal, the results will be much the same. But the researches in this branch of science have INTRODUCTORY REMARKS. 15 made us acquainted with facts yet more extraordinary, which we will here briefly record. It has been ob- served that some bodies, which, under the influence of dayh'ght, undergo certain chemical changes, have the power of restoring themselves to their original condi- tion in the dark. This phenomenon is displayed most strikingly in the iodide of platinum, which readily re» ceives a photographic image by darkening over the exposed surfaces, but speedily loses it by bleaching in the dark. The ioduret of Daguerre's plate, and some other iodides, exhibit the same peculiarity. We are hence led to the singular and striking fact that bodies which have undergone a change of state under the in- fiuence of daylight have some latent power by ivhich they can re?iov ate themselves. Possibly the hours of night are as necessary to inanimate nature as they are to men and animals. During the day, an excitement which we do not heed, unless in a state of disease, is maintained by the influence of light ; and the hours of repose during which the equilibrium is restored are most essential to the continuance of health. Instead of a few chemical compounds of gold and silverj which at first were alone supposed to be photographiCj we now know that copper, platinum, lead, nickel, and indeed, probably all the elements, are equally liable to change under solar influence. How great, then, must be the disturbance over the face of our planet during the period the sun is above the horizon 1 How varied must be the developements of electrical, chemi- cal, and calorific phenomena, under this excitation ! How beautiful that design by which, during external quiescence, matter is enabled to resume its former state, and during apparent rest busily to restore to the balance that which it has lost ! THOTOGENIG MANIPULATION. Another very remarkable effect of light is, that it appears to impart to bodies some power by which they more readily enter into chemical combination with others. We have already said that chlorine and hydrogen, if kept in the dark, will remain unaltered, but if the chlorine alone be previously exposed to sunshine, the chlorine thus solarized will unite with the hydrogen in the dark. Sulphate of iron will throw down gold or silver from their solutions slowly in the dark ; but if either solution be first exposed to sun- shine, and the mixture be then made in the dark, the precipitation takes place instantly. Here is again evidence of either an absorption of some material agent from the sunbeam, or of an alteration in the chemical constitution of the body. 12. Although it is utterly impossible, in a little work like this, to enter into a detail of the theories of light, still we deem it necessary to the clear apprehension of the subject, to allude briefly to the mode in which the chemical effects of light are accounted for on the un- dulatory theory. It is found by the prismatic spec- trum, that each ray of white light is made up of seven different kinds of light, of different colours, namely, — red, orange, yellow, green, blue, indigo, violet. Now, in the theory which supposes light to consist in the vibrations or undulations of a highly elastic medium, it is imagined that the waves of red light are longer than any of the others, and that the length decreases from the red to the violet, which is the shortest; hut the violet wave, in order to make up for this difference, is quicker in its travel, — that is to say, it creates a greater number of undulations in a given time. Now, the undulatory theorists farther suppose, that all che- mical change depends upon the motion communicated APPARATUS AND MATERIALS. 17 to the particles of ethereal fluid by these undulations, and that the violet ray would, therefore, by its greater rapidity of motion, produce the greatest chemical change. And this is found to be the case. So late as the year 1801, Mr. Ritter, of Jena, discovered that the chemical effects of the spectrum resided at the violet end, and that the red ray had little or no che- mical influence on the most sensitive preparations. 13. The knowledge of this fact has led Mr. Claii- det to construct the windows of his photogenic apart- ment at the Adelaide Gallery of blue glass, thus ex- cluding the rays which oppress vision without con- tributing to the photographic result, 14. We shall now proceed to describe in due order the various photographic processes. Before, how- ever, doing this, it is necessary, above all things, to impress on the mind of the experimenter, the neces- sity which exists for extreme care in every stage of the manipulation ; for it is but natural to suppose that ao art, which involves the most delicate chemi- cal changes, should require that more than ordinary caution should be taken in selecting the materials used for carrying it into eflect. !L — Appakatus and Materials, 15. Paper.— The principal difficulty to be con- tended with in using paper, is the different power of imbibition which we often find possessed by the same sheet, owing to trifling inequalities in its texture. This is, to a certain extent, to be overcome by a very careful examination of each sheet, by the light of a candle or lamp at night, or in the dark. By extend- ing each sheet between the light and the eye, and slowly moving it up and down, and from left to right, 2* 18 PHOTOGENIC MANIPULATION. the variations in its texture will be seen by the dif- ferent quantities of h'ght which pass through it indif- ferent parts ; and it is always the safest course to re- ject every sheet in which inequahties exist. Paper sometimes contains minute portions of thread, black or brown specks, and other imperfections, all of which materially interfere with the process. Some paper has an artificial substance, given to it by sulphate of lime (plaster of Paris) ,* this defect only exists, how- ever, in the cheaper sorts of demy, and therefore can be easily avoided. In all cases such paper should be rejected, as no really sensitive material can be ob- tained with it. Paper.makers,asis well known, usually affix their name and the date of manufacture to one half of the sheet; this moiety should likewise be placed aside, as the letters most frequently com.e out with annoying distinctness. Well sized paper is by no means objectionable, indeed, is rather to be preferred, since the size tends to exalt the sensitive powers of the silver. Unsized paper has been recommended by some, but experience would rather teach its impro- priety. The principal thing to be avoided, is the ab- sorption of the sensitive solution into the pores ; and it must be evident that this desideratum cannot be ob- tained by unsized paper. Taking all things into con- sideration, the paper known as satiii post would ap- pear to be preferable, although the precautions already recommended should be taken in its selection. As a general rule, the best paper for the purpose, is What- man's satin post, sold by nearly all stationers. A very thin paper is frequently used where the transfer of the photograph is required ; but by a process, else- where explained, this is not requisite. 16. Brashes, — The necessary solutions are to be APPARATUS AND MATERIALS. 19 laid upon the paper with a brush. Some persons pass the paper over the surface of the solution, thus licking up, as it were, a portion of the fluid ; but this method is apt to give an uneven surface unless great dexterity of manipulation be employed : it also rapidly spoils the solutions. At all events, the brush is the most ready and the most effectual means. It should be formed of camel or badger hair — should not have any metal in contact with it, and should be sufficiently broad and large to cover the paper in two or three sweeps ; for if a small one be employed, it will be evi- dent that many strokes must be given, which is very likely to leave corresponding marks. Many otherwise good pictures are spoiled by a neglect of this appa- rently trifling matter. It must further be remembered that each solution requires its distinct brush, which, after use must be immediately washed in distilled water. 17. Distilled Water, — All the water used both for mixing the solutions, washing the papers, or cleansing the brushes, must be distilled ; clean rain-water, how- ever, answers the purpose tolerably well. Common water holds various substances in solution, which will infallibly ruin the whole operations. It must likewise be remembered, that distilled water should never be used but for one operation; thus, for example, we must not wash the sensitive calotype paper, hereafter to be described, in the same water as that in which the fixed paper is to be placed and vice versa. The best and surest method is to change the water after use. Distilled water can be procured of most chemists ; but in an economical point of view, this is not an ad- vantageous way of obtaining it. The experimenter may easily distil it himself. Fig. 1 represents a convenient and economical still 20 PHOTOGENIC MANIPULATION. Fig. 1. for the purpose. The whole is made of tinned iron, and can be used on a common fire, a is the body holding one gallon of water, which is introduced at the opening 6, which is then stopped by a cork. The tube d connects the neck of the still with the worm tub or refrigeratory which is filled with cold water, a supply being kept up through the funnel c, the hot water is drawn off through the cock f; the different joints are rendered tight by lute, or in the absence of it, some stiff paste spread on a piece of broad tape, and put round them, answers very well. The distilled water is condensed in the worm, and passing off at the pipe is collected and preserved for use in a glass bottle. A glass retort connected with a Liebig's condenser forms a very convenient apparatus for distilling water, and may be heated either by an argand-lamp, gas-light, or small chaufl^er. 18. Blotting Paper, — In many instances, the pre- pared paper requires to be lightly dried with bibulous PREPARATION OF THE PAPER. 21 paper. The best description is the white sort, which may be obtained at most stationers. In each stage of the preparation distinct portions of bibulous paper must be used. If these be kept separate, and marked, they can be again employed for the same stage ; but it would not do, for example, to dry the finished picture in the same folds in which the sensi- tive paper had been pressed. A very convenient method is to have two or three quarto-size books of bibulous paper, one for each separate process. 19. Nitrate of Silver, — In the practice of the pho- tographic art, much depends on the nitrate of silver. Care should be taken to procure the best ; the crys- tallized salt is most suitable for the purpose, the variety sold in sticks, under the name of lunar caustic, not answering so well. While in the form of crystal it is not injured by being exposed to light, but the bottles containing the solutions of this salt should at all times be kept wrapped in dark paper, and excluded from daylight. III. — Different Methods of Preparing the Paper. 20. Preparation of the Paper. — Dip the paper to be prepared into a weak solution of common salt. The solution should not be saturated, but six or eight times diluted with water. When perfectly moistened, wipe it dry with a towel or press it between bibulous paper, by which operation the salt is uniformly dispersed throughout its substance. Then brush over it, on one side only, a solution of nitrate of silver. The strength of this solution must vary according to the colour and sensitiveness required. Mr, Talbot recommends about fifty grains of the salt to an ounce of distilled water. Mr. Golding Bird advises twenty grains only to the 22 PHOTOGENIC MANIPULATION. ounce. I have been accustomed to use a solution of the strength of eighty grains to an ounce, and I have found it to make an excellent and very sensitive paper. When dried in a dark room, the paper is fit for use. To render this paper still more sensitive, it must again be washed with salt and water, and afterwards with the same solu- tion of nitrate of silver, drying it between times. This paper, if carefully made, is very useful for all ordinary photogenic purposes. For example, nothing can be more perfect than the images it gives of leaves and flowers, especially with a summer's sun : the light, passing through the leaves, delineates every ramifica- tion of their fibres. In conducting this operation, however, it will be found that the results are sometimes more and sometimes less satisfactory, in consequence of small and accidental variations in the proportions employed. It happens sometimes that the chloride of silver formed on the surface of the paper is disposed to blacken of itself, without any exposure to light. This shows that the attempt to give it sensibility has been carried too far. The object is, to approach as nearly to this condition as possible without reaching it ; so that the preparation may be in a state ready to yield to the slightest extraneous force, such as the feeblest effect of light. 21 . Cooper'' s Method, — Soak the paper in a boiling- hot solution of chlorate of potash (the strength matters not) for a few minutes ; then take it out, dry it, and wet it with a brush on one side only with a solution of nitrate of silver, sixty grains to an ounce of distilled water, or, if not required to be so sensitive, thirty grains to the ounce will do. This paper possesses a great advantage over any other, for the image can be fixed by mere washing. It is, however, very apt to PREPARATION OF THE PAPER. 23 become discoloured even in the making, or shortly afterwards, and is, besides, not so sensitive, nor does it become so dark as that made according to Mr. Talbot's method. 22. Daguerre's Method.— Immerse the paper in hydrochloric (or, as it is more commonly called, muri- atic) ether, which has been kept sufficiently long to have become acid ; the paper is then carefully and completely dried, as this is essential to its proper preparation. It is then dipped into a solution of nitrate of silver, and dried without artificial heat in a room from which every ray of light is carefully excluded. By this process it requires a very remark- able facility in being blackened on a very slight expo- sure to light, even when the latter is by no means intense. The paper, however, rapidly loses its extreme sensitiveness to light, and finally becomes no more impressionable by the solar beams than common ni- trate paper. 23. Bromide Paper. — Of all common photographic paper, the best, because the least troublesome in making, and the most satisfactory in result, is that which is termed bromJde paper, and which is thus prepared : — Dissolve 100 grains of bromide of potas- sium in one ounce of distilled water, and soak the paper in this solution. Take off the superfluous moisture, and when nearly dry, brush it over on one side only with a solution of 100 grains of nitrate of silver to an ounce of distilled water. The paper should then be dried in a dark room, and if required to be very sensitive, should a second time be brushed over with the nitrate of silver solution. 24. In preparing the papers mentioned above, there are two circumstances which require particular atten- 24 PHOTOGENIC MANIPULATION. tion. In the first place, it is necessary to mark one side of the paper. It will be seen in every one of the methods of which mention has been made, that the nitrate of silver solution is applied to one side only. In order, therefore, to be able to know the sensitive side, it is necessary to make a mark on its extreme edge. This answers two purposes: in the first place, it serves to inform the experimentalist of the sensitive surface ; and secondly, it will be a guide as to which ■portion of the paper has been handled during the appli- cation of the solution, as the impress of the finger will probably come out upon the photograph. The second caution is, that the application of the sensitive solution (nitrate of silver) and the subsequent drying of the paper, must be always conducted in a perfectly dark room, the light of a candle being alone used. IV. — Photogenic Drawing and its Application^ 25. The simplest mode is to procure a flat board and a square of plate glass, larger in size than the object intended to be copied. On the board place the photogenic paper with the prepared side upwards, and upon it the object to ,be copied ; over both lay the glass, and secure them so that they are in close con- nexion by means of binding screws or clamps, similar to G, G, Fig. 2. Should the object to be copied be of unequal thickness, such as a leaf, grass, &c., it will be necessary to place on the board, first, a soft cushion, which may be made of a piece of fine flannel and cotton wool. By this means the object is brought into closer contact with the paper, which is of great consequence, and adds materially to the clearness of the copy. The paper is now exposed to diflxised day- light, or, still better, to the direct rays of the sun, DRAWING. 25 when that part of the paper not covered with the object will become tinged with the violet colour, and if the paper be well prepared, it will in a short tinne pass to a deep brown or bronze colour. It must then be removed, as no advantage will be obtained by keeping Fig. 2. it longer exposed ; on the contrary, the delicate parts yet uncoloured wmU become in some degree affected. The photogenic paper will now show a more or less white and distinct representation of the object. Fig. 2 represents a more convenient apparatus : it consists of a wooden frame similar to a picture-frame; a piece of plate glass is fixed in front ; and it is provided with a sliding cover of wood, C, which is removed when the paper is ready to be exposed to the action of the light. The back, D, which is furnished with a cushion, as just described, is made to remove for the purpose of intro- ducing the object to be copied, and upon it the pre- pared paper; the back is then replaced, and, by aid of the cross piece and screw, E, the whole is brought into close contact with the glass. 3 26 PHOTOGENIC MANIPULATION. 26. The objects best delineated on these photo- graphic papers, are lace, feathers, dried plants, par- ticularly the ferns, sea-weeds, and the light grasses, impressions of copper-plate and wood engravings, particularly if they have considerable contrast of light and shade — (these should be placed with the face downwards, having been previously prepared; § 30), paintings on glass, stained windows, etchings, &c. 27. To fix the Draivings. — Mr. Talbot recom- mends that the drawing should be dipped in salt and water, and in many instances this method will succeed, but at times it is equally unsuccessful. Iodide of po- tassium, or, as it is frequently called, hydriodate of potash, dissolved in water, and very much diluted (25 grains to 1 oz. of water), is a more useful prepa- ration to wash the drawings with ; it must be used very weak or it will not dissolve the unchanged muriate only, as is intended, but the blackened oxide also, and the drawing be thereby spoiled. 28. But the most certain material to be used is the hyposulphite of soda. 1 oz. of this salt should be dissolved in about a pint of distilled water. Having previously washed the photogenic drawing in a little lukewarm water, v/hich of itself removes a large por- tion of the muriate of silver which is to be got rid of, it should be dipped once or twice in the hyposulphite sohition. By this operation the muriate which lies upon the lighter parts will become so altered in its nature as to be unchanged by light, while the rest remains dark as before. 29. It will be evident, from the nature of the pro- cess, that the lights and shadows of an object are re- versed. That which is originally opaque will intercept the light, and consequently those parts of the photoge- DRAWING. 27 nic paper will be least influenced by light, while any part of the object which is transparent, by admitting the light through it will suffer the effect to be greater or less in exact proportion to its degrees of transpa- rency. The object wholly intercepting the light will show a white impression ; in selecting, for example, a butterfly for an object, the insect, being more or less transparent, leaves a proportionate gradation of light and shade, the most opaque parts showing the whitest colours. It may be said, therefore, that the represen- tation is not natural. This is admitted, and in order to obtain a just delineation, we must place our first acquired photograph upon a second piece of photo- genic paper. Before we do this, however, we must render our photographic picture transparent, otherwise the opacity of the paper itself will mar our efforts, 30. To accomplish this object, the back of the paper containing the negative or first acquired photo- graph should be covered with white or virgin wax. This may be done by scraping wax upon the paper, and then, after placing it between two other portions of paper, passing a heated iron over it. The picture, being thus rendered transparent, should now be ap- plied to a second piece of photogenic paper, and ex- posed, in the manner before directed, either to diffused daylight or to the direct rays of the sun. The light will now penetrate the whiter parts, and the second photograph be the reverse of the former, or a true picture of the original. In lieu of wax, I have been accustomed to make use of boiled oil, a preparation obtained at any oil- shop. The back of the negative photogragh should be smeared with the oil, and then placed between folds of bibulous paper. When dry, the photograph is highly transparent. 28 PHOTOGENIC MANIPULATION. 31. Application, — Mr. Talbot has recorded so many applications of the art of photography, that little can be added to the list. They may be summed up briefly as follows : — The copying of paintings on glass by the light thrown through them on the prepared paper. Imita- tions of etchings, suggested by Mr. Havel!, but since claimed by Mr. Talbot. These are done by painting a piece of glass with a thick coat of white oil paint ; when dry, with the point of a needle, lines or scratches are to be made through the white lead ground, so as to lay the glass bare; then place the glass upon a piece of prepared paper, and of course every line will be represented beneath of a black colour, and thus an imitation etching will be produced. The delineation of microscopic objects, architecture, sculpture, land- scapes, and external nature. 32. A novel application of this art has been recently suggested, which would doubtless prove useful in very many instances. By rendering the wood used for engraving sensitive to light, impressions of objects- may be at once made thereon, without the aid of the artist's pencil. The preparation of the wood is simply as follows : — place its face or smooth side downwards, in a plate containing twenty grains of common salt dissolved in an ounce of water ; here let it remain for five minutes, take it out and dry it ; then place it again face downwards in another plate containing sixty grains of nitrate of silver to an ounce of water ; here let it rest one minute, when taken out and dried in the dark it will be fit for use, and wiil become, on expo- sure to light, of a fine brown colour. Should it be required more sensitive, it must be immersed in each solution a second time, for a few seconds only. It will THE CAIvlERA. 29 now be very soon afFected by a very diffused daylight. This process naay be useful to carvers and wood-en- gravers ; not only to those who cut the fine objects of artistical design, but still more to those who cut pat- terns and blocks for lace, muslin, calico-printing, paper-hangings, &c., as by this means the errors, expense, and time of the draughtsman may be wholly saved, and in a minute or two the most elaborate picture or design, or the most complicated machinery, be delineated with the utmost truth and clearness, V. — The Ca3iera. 33. Camera, — We shall now proceed to a descrip- tion of the Photographic Camera, an instrument which we have hitherto scarcely named, as the various papers we have been describing are none of them sufTiciently sensitive to be used in it, requiring a stronger light, as well as a very considerable time before an image could be impressed upon them. To Mr. Fox Talbot is due the credit of discovering a process, by which paper can be rendered so sensitive that it can be readily acted upon by the light in the camera ; " and the fleeting shadows as they pass" both caught and re- tained. His process, which is patented under the name of Calotype, as well as that discovered about the same period by Daguerre, and called Daguerreotype, we shall presently describe. The camera is, without doubt, the most important instrument in the photoge- nic art; consequently, it has undergone many modi- fications. The photographic camera differs from the ordinary camera-obscura: in the latter a considerable portion of light is unavoidably lost. At first sight the former appears to be a very simple piece of appJara- tus. It consists essentially of a wooden box, A, Fig, 3* 30 PHOTOGENIC MANIPULATION. F\g. 3. 3, at one end of which is the arrangement of lenses B, and at the other the ground-o-lass C, fitted into a wooden-frame sliding into a groove. The camera being placed opposite any object, it is delineated on the semi-transparent glass C. The proper focus is obtained, either by an adjustment in the mounting of the lenses or in the wood-work. D represents the frame for holding the prepared paper, or silver plate ; it is shown open. The dark side E being down, the THE CAMERA. 31 plate or paper is placed in the frame, and the flap F closed ; this, of course, being done in the dark. The object to be taken being clearly portrayed on the ground -glass, care must be observed that the camera is not moved ; and for this purpose it should be fixed to a firm table, or to a tripod stand (very conve- nient ones may now be obtained). The cap or slide is now fixed over the front of the lens, the ground- glass removed, and in its stead the frame containing the plate or paper is placed. The slide E being now raised, the cap is removed from the lens when the light acts upon the plate or paper, which having re- mained the proper time, the cap is replaced on the lens, the slide E put down, when the frame D can be removed entirely from the camera. This is the pho- togenic camera in its simplest form. As the art has advanced, various alterations and improvements have been made. Fi^. 1 Fig. 4 represents the modern French form of ca- mera, half the body A sliding into the other half B. This has the advantao;e of renderins^ the instrument 32 PHOTOGENIC MANIPULATION. more portable, and allowing a greater range ; so that lenses, differing considerably in their focal length, can be used if necessary. C shows the frame, with its dark slide for holding the plate or paper. Messrs. Knight and Sons, the publishers of this little treatise, have taken considerable pains in their endeavours to construct an instrument that should be as complete in its various parts, and as portable in itself as possible. The result of their ingenuity is well worthy the attention of all travellers and tourists who have any idea of practising this Bew and Dsefel art during their rambles^ Messrs. Knights' camera some- what resembles the French instrument. Fig. 4 ; hot the top, bottom, and sides are equal. This allows of the plates being placed either in a horizontal or verti- cal position, without the inconvenience of turning the camera on its side, which is the case in the French form. The plate-holder is made double, the plates themselves being fixed in an inner frame, made ex- tremely light though strong, so that a considerable number, each with its prepared plate, can be packed within the body of the camera. They can also be placed when required in the outer frame, similar to C, Fig. 4, and removed from it without any risk of ex- traneous light impinging on the sensitive surface. Fig. 5 represents the German, or Voigtlandei's Camera ; it is made entirely of brass, so that variation of climate has no efiect upon it. It is very portable, and when packed in its box, with all the necessary apparatus and materials for practising the Daguerreo- type art, occupies but little space. It is not, however, well adapted for the calotype process. The brass foot A, is placed on a table, or other firm support, and the pillar B screwed into it ; the body of THE CAMERA. 33 the camera C C is laid into the double-forked bearing D D. The instrument is now properly adjusted by means of the set screws c e e In the brass foot, or it may be raised, lowered, or moved from one side to the other, by the telescope-stand, and when correct, fixed by the screw b. The landscape or portrait to be de- lineated is viewed either through the smail lens g, or with the naked eye on the ground-glass plate H, the focus being adjusted by the screw L The optica! part Fig. 5. of the instrument consists of the small set "of achro- matic lenses presently to be described. When the view or portrait to be taken is delineated on the 34 PHOTOGENIC MANIPULATION. ground-glass to the entire salisfaction of the opera- tor, the brass cap L is placed over the lens, and the entire body is removed away into the dark, taking care not to disturb the position of the stand. The body is now detached at the part H, and the prepared paper or plate inclosed in the brass franfje K intro- duced in its place; the whole is again placed on the pedestal, the brass cap L is removed by which the paper or plate is exposed to the full influence of the light, after which the cap is again replaced. Mr. Claudet, the well-known and successfol opera- tor in this interesting art at the Adelaide Gallery., and the first person to purchase a license onder the original Daguerreotype patent, patented himself^ amongst other matters connected with it, sc camera. Its chief merit is, that different lenses are readily adapted to it, and it is provided with a variety of frames for various-sized plates. Mr. Beard, the gentleman who subsequently pur- chased the remainder of the Daguerreotype patent^ patented a camera in which lenses were altogether laid aside, and their place supplied by a concave mirror. The advantage derived from this construc- tion is the greater rapidity with which it acts, but there are many inconveniences attached to it ; it is only applicable to the small-sized plates, neither is it so portable or easy of management as the others. It is very little used by amateurs, but principally con- fined to the photographic establishments licensed by Mr. Beard. 34. The Lenses.— These should be achromatic^ more especially if we are operating on plates and not paper (Daguerreotype). The diameter and focal length must depend in a great measure on the dis- THE CAMERA. 35 tance of the object, and also on the superficies of the plate or paper to be covered. For portraits, one of 1 1 in. diameter, and from 4J in, to 5^ in. focus may be used ; but for distant views, one from 2 in, to 3 in. diameter, and from 8 in. to 12 in. focal length will be found 10 answer better. For simple lenses, the aper- ture in front should be placed at a distance from it, corresponding to the diameter, and of a size not more than one-third of the same. A variety of movable apertures, or diaphragms, are often useful, as by them the intensity of the light may be modified, and more or less distinctness and clearness of deh'neation obtained. Though the single achromatic lens answers very well for copying engravings, taking views from nature, buildings, &c., for the portrait, figures, and groups from life, it is almost entirely superseded by the double achromatic, which acts very much more quickly ; and these have been brought to the greatest state of per- fection by M. Voigtlander, of Vienna, under the direc- tion of Dr. Petzval, Professor of Mathematics in that university. His small-size arrangement consists of two separate achromatic lenses ; the first, or external one, has a free aperture of in.; the second, 1| in. ; and both have the same focus, viz. 5| in. The larger size dififers from the smaller ; the inner lens is an achromatic 3| in. diameter, its focal length 30 in. ; the second, or outer lens, is a meniscus, having a focal length of 18 in. The combined length of the two being 10| in. For very distant views the aperture in front is contracted to |- of an inch. By these means the light is reflected with considerable intensity, and the clearness and correctness of the delineation, are truly surprising. The success of the arrangement is evident from the general adoption 86 PHOTOGENIC MANIPULATION. of these cameras in taking of portraits, where the greatest perfection is required. Mr. Cundeil, in a paper published in the Philoso- phical Magazine,* " On the Practice of the Calotype Process," and containing much useful information, recommends a lens of the meniscus form, of about 12 in. focus. This when mounted, should have an aperture of 2y^^ in. A diaphragm is placed at 1$ in. in advance of the lens, and its opening ought not to exceed 1^^ in. By using one of smaller opening a much finer image will be obtained, but at the sacrifice of light. At short distances, however, on account of the increasing divergence of the rays, only a small opening, admitting the mere centres of the pencils, can be used with advantage. With this arrange- ment the size of the paper may be eight inches by six. ^- It must be observed of this camera, and of all others which are not achromatic, that there is a peculiar adjustment required of the focus, the not attending to which has been the cause of much failure and disappointment. The instrument must be ad- justed to what has been appropriately called the che- mical focus, which difiers materially from the optical or visible focus, the former being about one thirty- sixth part shorter than the latter for parallel rays, and for diverging rays still more according to the degree of divergence." VJ . C A L 0 TYPE . 35. In January 1839, Mr. Henry Fox Talbot's re- searches in the photogenic art were first made known in a paper read before the Royal Society, and in the * Phil, Mag., No. 160, vol. xsiv. May, 1844. CALOTYFE. 37 fol lowing month this paper was succeeded by another, when the method of preparing the paper was given, and the process by which the design was fixed par- ticularly described. Subsequently, further improve- ments w^ere made, and in the same year, Mr. Talbot patented his process under the name of " Calotype." 36. Before entering upon a description of it, it would be as well to enumerate the apparatus and materials required by the experimentalist previously to his proceeding to practise it. They are two or three shallow dishes, A A Fig. 12, for holding dis- tilled water, iodide, potassium, &c., the same water never being used for two different operations, white bibuloiLS paper, photogenic camera. Pressure frame, Fig. 2. A screen of yellow glass. In preparing the calotype paper, it is necessary to be extremely careful, not only to prevent the daylight impinging on it, but also to exclude, if possible, the strong glare of the candle or lamp. This may be effected by using a shade of yellow glass or yellow gauze, which must be placed around the candle or lamp. Light passing through such a medium will scarcely affect the sensitive compounds, the yellow glass intercepting the chemical rays. Camel or badger hair brushes : — a separate one being kept for each stage of the process, and imme- diately after being used it should be washed in distilled water. That used for the gallo-nitrate is soon de- stroyed, owing to the rapid decomposition of thai preparation. A graduated measure, A hot water apparatus for drying the paper will ba found extremely useful, 4 38 PHOTOGENIC MANIPULATION. Three or four flat boards, to which the paper may be fixed with drawing pins. The paper must be of the very best, as described (§ 15). 37. Freparation of the Iodized Paper, — Dissolve 100 grains of crystallized nitrate of silver in six ounces of distilled water, and having fixed the paper to one of the boards, brush it over with"^ a soft brush on one side only with this solution, a mark being placed on that side whereby it may be known. When nearly dry, dip it into a solution of iodide of potassium, containing 500 grains of that salt dissolved in a pint of water. When perfectly saturated with this solu- tion, it should be washed in distilled water, drained, and allowed to dry. This is the first part of the process, and the paper so prepared is called iodized paper. It should be kept in a portfolio or drawer until required : with this care it may be preserved for any length of time without spoiling or undergoing any change. Mr. Cundell, in his paper before referred to, (§ 34), states, that he finds a stronger solution of nitrate of silver preferable, and that he employs thirty grains to the ounce of distilled water : he also adds fifty grains of common salt to the iodide of potassium, which he applies to the marked side of the paper only. This is the first process. 38. Prepa^ration of the Paper for the Camera, — The second process consists in applying to the above a solution which has been named by Mr. Talbot the " Gallo-Nitrate of Silver it is prepared in the fol- lowing manner : dissolve 100 grains of crystallized nitrate of silver in two ounces of distilled water, to which is added one-sixth of its volume (that is to say 2-| drachms) of strong acetic acid. This solution THE CALOTYPE. 39 should be kept in a bottle carefully excluded from the light. Now, make a saturated solution of gallic acid in cold distilled water : the quantity dissolved is very small. When it is required to take a picture, the two liquids above described should be mixed together in equal quantities ; but as it speedily undergoes decom- position, and will not keep good for many minutes, only just sufficient for the time should be prepared, and that used without delay. It is also well not to make much of the gallic acid solution, as it will not keep for more than a few days without spoiling. A sheet of the iodized paper should be washed over with a soft brush with this mixed solution, care being taken that it be applied to the marked side. This operation must be performed by candlelight. Let the paper rest half a minute, then dip it into one of the dishes of cold water, Fig. 12, passing it beneath the surface several times : it is now allowed to drain, and dried, by placing its marked side upwards on the drying apparatus. It is better not to touch the surface with bibulous paper : it is now highly sensitive, and is ready to receive the impression. In practice, it is found better and more economical not to mix the nitrate of silver and gallic acid, but only to brush the paper with the solution of the nitrate. Mr.. Talbot has recently proposed some modifica- tions in his method of preparing the calotype paper. The paper is first iodized in the usual way ; it is then washed over with a saturated solution of gallic acid in distilled water and dried. Thus prepared, he calls it the io-gallic paper : it will remain good a considerable time, if kept in a press or portfolio. When required for use, it is washed with a solution of nitrate of silver (fifty grains to the ounce of distilled water), and it is then fit for the camera. 40 PHOTOGENIC MANIPULATION. 39. Exposure in the Camera, — The calotype paper thus prepared possesses a very high degree of sensi- bility when exposed to light, and we are thus provided with a mediunn by which, with the aid of the photo- genic camera, we may effectually copy views from nature, figures, buildings, and even take portraits from the shadows thrown on the paper by the living face. The paper may be used somewhat damp. The best plan of fixing it in the camera is to place it be- tween a piece of plate glass and some other material with a flat surface, as a piece of smooth slate or an iron plate, which latter, if made warm, renders the paper more sensitive, and consequently the picture is obtained more rapidly. Time of Exposure, — With regard to the time which should be allowed for the paper to remain in the camera, no direct rules can be laid down ; this will depend altogether on the nature of the object to be copied, and the light which prevails. All that can be said is, that the time necessary for forming a good picture varies from thirty seconds to five minutes, and it will naturally be the first object of the operator to gain by experience this important knowledge. 40. Bringing out the Ficture, — The paper when taken from the camera, which should be done so as to exclude every ray of light, bears no appearance of the picture which in reality is formed. The impression is latent and invisible, and its existence would not be suspected by any one who was not acquainted with it by previous experiments. The method of bringing out the impression is extremely simple. It consists in washing the paper with the gallo-nitraie of silver^ prepared in the way already described, and then warm- ing it gently, being careful at the same time not to THE CALOTYPE. 41 let any portion becon^e perfectly dry. In a few seconds the part of the paper upon which the light has acted will begin to darken, and finally grow en- tirely black, while the other part of the paper retains its original colour. Even a weak impression may be brought out by again washing the paper with the gallo-nitrate, and once more gently warming it. When the paper is quite black, as is generally the case, it is a highly curious and beautiful phenomenon to witness the spontaneous commencement of the picture, first tracing out the stronger outHnes, and then gradually filling up all the numerous and com- plicated details. The artist should watch the picture as it developes itself, and when in his judgment it has attained the greatest degree of strength and clearness, he should stop further proceedings by washing it with the fixing liquid. Here again the mixed solu- tion need not be used, but the picture simply brushed over with the solution of gallic acid. 41. The Fixing Process. — ''In order to fix the picture thus obtained, first dip it into water, then part- ly dry it with blotting-paper, and wash it with a solu- tion of bromide of potassium containing 100 grains of that salt dissolved in eight or ten ounces of distilled water. The picture is again washed with distilled water, and then finally dried. Instead of bromide of potassium, a solution of hyposulphite of soda, as di- rected (§ 28), may be used with equal advantage. 42. It was at one ti-me supposed that terrestrial or artificial light possessed no chemical rays, but this is incorrect; Mr. Brande discovered that although the concentrated light of the moon, or the light even of defiant gas, however intense, had no effect on chlo- ride of silver, or on a mixture of chlorine and hydro- 4* 42 PHOTOGENIC MANIPULATION. gen, yet the light emitted by electrized charcoal blackens the salt. At the Royal Polytechnic Institu- tion pictures have been taken by means of sensitive paper, acted, upon by the Drummond light. But it must of course be distinctly understood that they are far inferior to those taken by the light of the sun or diffused daylight. 43. The calotype picture, like the photographic one which we first described, is negative, that is to say, it has its lights and shades reversed, giving the whole an appearance not conformable to nature. But it is easy from this picture to obtain another which shall be conformable to nature, viz., in w^hich the lights shall be represented by lights, and the shades by shades. It is only necessary for this purpose to take a sheet of photogenic paper (the bromide paper is the best), and place it in contact with a calotype picture, previously rendered transparent in the manner before recommended, § 30. Fix it in the frame Fig. 2, ex- pose it in the sunshine for a short time, and an image or copy will be formed upon the photogenic paper. The calotype paper itself may be used to take the second picture, but this Mr. Talbot does not recom- mend, for although it takes a much longer time to take a copy on the photogenic paper, yet the tints of such copy are generally more harmonious and agree- able. After a calotype picture has furnished a good many copies it sometimes grows faint, and the subse- quent copies are inferior. This may be prevented by means of a process which revives the strength of the calotype pictures. In order to do this, it is only necessary to w^ash them by candle-light with gallo-ni- trate of silver, and then warm them. This causes all the shades of the picture to darken considerably, while THE CALOTYPE. 43 the white parts arc unaffected. After this the picture is of course to be fixed a second time. It will then yield a second series of copies, and a great number of them may frequently be made." 44. The calotype pictures when prepared as we have stated possess a yellowish tint, which impedes the pro- cess of taking copies from them. In order to remedy this defect, Mr. Talbot has devised the following method. The calotype picture is plunged into a solu- tion consisting of hyposulphite of soda dissolved in about ten times its weight of water, and heated nearly to the boiling point. The picture should remain in about ten minutes; it must then be removed, washed, and dried. By this process the picture is rendered more transparent, and its lights become whiter. It is also rendered exceedingly permanent. After this process the picture maybe waxed, as described § 30, and thus its transparency is increased. This pro- cess is applicable to all photographic papers prepared with solutions of silver. 45. Having thus fully, and it is hoped clearly, con- sidered the process, it may be necessary, before en- tirely dismissing the calotype from notice, to add one or two remarks from the observations and labours of some who have experimented in this art. Dr. Ryan, in his lectures on this subject at the Polytechnic In- stitution, has observed, that in the iodizing process the sensitiveness of the paper is materially injured by keeping it too long in the solution of iodide of potas- sium, owing to the newly formed iodide of silver being so exceedingly soluble in excess of iodide of potassium, as in a few minutes to be completely re- moved. The paper should merely be dipped in the solution and instantly removed. 44 PHOTOGENIC MANIPULATION. There is another point, too, in the preparation of the iodized paper in which Mr. Mitchell, Dr. Ryan's assistant, suggests a slight deviation from Mr. Talbot's plan. In the first instance, he recommends the paper to be brushed over with the solution of the iodide of potassium, instead of the nitrate of sil ver, transposing, in fact, the application of the first two solutions. The paper, having been brushed over with the iodide of potassium in solution, is washed in distilled water and dried. It is then brushed over with nitrate of silver, and after drying is dipped for a moment in a fresh solution of iodide of potassium of only one- fourth the strength of the first, that is to say, con- sisting of 125 grains of the salt dissolved in one pint of water. After this it is again washed and dried. The advantage derived from this method is a more sensitive paper, and a more even distribution of the compounds over the surface. The following deviation from Mr. Talbot's method has been suggested and stated to answer equally well. 46. Brush the paper over with a solution of nitrate of silver, containing 100 grains of that salt to 1 oz. of distilled water. When nearly but not quite dry, dip it into a solution of iodide of potassium of the strength of twenty-five grains of the salt to one ounce of distilled water, drain it, wash it in distilled water, and again drain it. Now brush it over w^ith aceto-nitrate of silver made by dissolving fifty grains of nitrate of silver in one ounce of distilled water, to which is added one-sixth of its volume of strong acetic acid. Dry it with bibulous paper, and it is now ready for receiving the image. When the impression has been received, which will require from one to five minutes according to the state of the weather, it must be washed THE POSITIVE CALOTYPE. 45 wilh a saturated solution of gallic acid to which a few drops of the aceto-nitrate of silver, made as above, have been added. The image will thus be gradually "brought out, and may be fixed with hyposulphite of soda. To obtain the positive picture, paper must be used brushed over with an ammonio-nitrate of silver made thus : — forty grains of nitrate of silver is to be dissolved in one ounce of distilled water, and liquid ammonia cautiously added till it re-dissolves the pre- cipitate. 47. A pleasing effect may be given to calotype, or indeed to all photographic pictures, by waxing them at the back, as described § 30, and mounting them on white paper, or if coloured papers be used5 various beautiful tones of colour are produced. VIT. — Positive Calotype, 48. At the last meeting of the British Association, at York, Professor Grove described a process by which positive calotype pictures could be directly obtained, and thus the necessity of transfer by which the imper- fections of the paper are shown, and which is more- over a troublesome and tedious process, is avoided. As light favours most chemical actions, Mr. Grove was led to believe that a paper darkened by the sun (which darkening is supposed to result from the pre- cipitation of silver) might be bleached by using a solvent which would not attack the silver in the dark, but would do so in the light. The plan found to be most successful is as follows ordinary calotype paper is darkened till it assumes a deep brown colour, almost amounting to black; it is then redipped into the ordinary solution of iodide of potassium, and dried. When required for use, it is drawn over dilute nitric 46 PHOTOGENIC MANIPULATION. acid, 1 part acid to 2i parts water. In this state, those parts exposed to the light are rapidly bleached, while the parts not exposed remain unchanged. It is fixed by washing in water, and subsequently in hyposulphite of soda, or bromide of potassium. 49. Mr. Grove likewise described on the same oc- casion another process which promises, when carried out, to be of great utility. It is the conversion of a negative calotype into a positive one, and was thus stated :— let an ordinary calotype image or portrait be taken in the camera, and developed by gallic acid ; then drawn over iodide of potassium and dilute nitric acid and exposed to full sunshine ; while bleaching the dark parts, the light is redarkening the newly precipitated iodidp in the lighter portions, and thus the negative picture is converted into a positive one. 50. The Calotype has already been applied in the arts, and Mr. Talbot has patented a process for print- ing, through its agency. His method is as follows: — ■ some pages of letter-press are taken printed on one side only; they are waxed (§ 31.) to render them more transparent, and the letters are cut out and sorted. To compose a new page, lines are ruled on a sheet of white paper, and the words are formed by fixing the separate letters in their proper order. The page being ready, a negative photograph is produced from it, from which the requisite number of positive photogenic copies may of course be obtained. The second method, which requires the use of the camera, consists in employing large letters painted on rectangular pieces of wood, coloured white. These are arranged in lines on a tablet or board, by slip- ping them into grooves which keep them steady and upright, thus forming a page on an enlarged scale. THE CHRYSOTYPE. — C7AN0TYPE. 47 It is now placed before a camera, and a reduced image of it of the required size is thrown upon the sensitive paper. The adjustments must be kept invariable, so that the consecutive pages may not vary from one another in the size of the type. VIII. ClIRYSOTYPE. 51. A modification of Mr. Talbot's process, to which the name of Chrysotype* was given by its dis- coverer, Sir John Herschel, was communicated in June 1843 to the "Royal Society, by that distinguished philosopher. The modification would appear lo unite the simplicity of photography with all the clearness and distinctness of calotype. This preparation is as follows : — the paper is to be washed in a solution of ammonio-citrate of iron ; it must then be dried, and subsequently brushed over with a solution of the ferro- sesquicyanuret of potassium. This paper, when dried in a perfectly dark room, is ready for use in the same manner as if otherwise prepared, the image being subsequently brought out by any neutral solution of gold. Such was the first declaration of his discovery, but he has subsequently found that a neutral solution of silver is equally useful in bringing out the picture. Sir John Herschel observes, that photographic por- traits taken on this paper are distinguished by a clearness of outline foreign to all other methods. IX. — Cyanotype. 52. So called from the circumstance of cyanogen in its combinations with iron performing a leading part in the process ; it is likewise a discovery of Sir John Herschel. It has also been termed Ferrotype. * From xpvco; gold, and rvirog a picture. 48 PHOTOGENIC MANIPULATION. The process is a simple one, and the resulting pic- tures are blue." Brush the paper over with a solution of the ammonio-citrate of iron. This solution should be sufficiently strong to resennble sherry-wine in co- lour. Expose the paper in the usual way, and pass over it very sparingly and evenly a wash of the common yellow ferro-cyanate of potass. As soon as the liquid is applied, the negative picture vanishes, and is replaced by a positive one, of a violet blue colour on a greenish yellow ground, which at a cer- tain time possesses a high degree of sharpness, and singular beauty of tint. A curious process was discovered by Sir John Her- schel, and communicated by him to the British Asso- ciation during the past year, by which dormant pic- tures are produced capable of developement by the breath, or by keeping in a moist atmosphere. It is as follows : If nitrate of silver, specific gravity 1 -200, be added to ferro-tartaric acid, specific gravity 1*023, a precipitate falls, which is in a great measure redis- solved by a gentle heat, leaving a black sediment, which, being cleared by subsidence, a liquid of a pale yellow colour is obtained, in which the further addi- tion of the nitrate causes no turbidness. When the total quantity of the nitrated solution added amounts to about halfthe bulk of the ferro-tartaric acid, it is enough. The liquid so prepared does not alter if kept in the dark. Spread on paper, and exposed wet to the sunshine (partly shaded) for a few seconds, no im- pression seems to be made, but by degrees, although withdrawn from the action of the light, it developes itself spontaneously, and at length becomes very in- tense. But if the paper be thoroughly dried in the dark (in which state it is of a very pale greenish yellow co- THE ENERGIATYPE. 49 lour), it possesses the singular property of receiving a dormant or invisible picture, to produce which from thirty seconds' to a minute's exposure in the sunshine is requisite. It should not be exposed too long, as not only is the ultimate effect less striking, but a picture begins to be visibly produced, which darkens spon- taneously after it is withdrawn. But if the exposure be discontinued before this effect comes on, an invisible impression is the result, to develope which all that is necessary is to breathe upon it, when it immediately appears, and very speedily acquires an extraordinary intensity and sharpness, as if by magic. Instead of the breath, it may be subject to the regulated action of aqueous vapour, by laying it in a blotting paper book, of which some of the outer leaves on both sides have been damped, or by holding it over warm water. X. — Energiatype. 53. Under this title a new process has been lately brought forward by Mr. Hunt. This consists in the application of a solution of succinic acid to paper, which is subsequently washed over with nitrate of sil- ver. The image is then to be taken either in the camera or otherwise as required, and is brought out by the application of the sulphate of iron in solution. Although this process has not come into general use, its exact description may prove interesting to the reader, and we therefore subjoin it. The solution with which the paper is first washed is to be prepared as follows : — succinic acid, two drachms ; common salt, five grains; mucilage of gum arabic, half a fluid drachm ; distilled water, one fluid drachm and a half. When the paper is nearly dry, it is to be brushed over with a solution of nitrate of silvefj containing a 5 50 PHOTOGENIC MANIPULATION. drachm of the salt, to an ounce of distilled water. It is now ready for exposure in the camera. To bring out the dormant picture it is necessary to wash it with a mixture of a drachm of concentrated solution of the green sulphate of iron and two drachms and a half of mucilage of gum arable. Subsequently, however, it has been found that the sulphate of iron produces upon all the salts of silver effects quite as beautiful as in the succinate. On the iodide, bromide, acetate, and benzoate, the effects are far more pleasing and striking. When pictures are produced, or the dormant camera image brought out, by the agency of sulphate of iron, it is remarkable how rapidly the effect takes place. Engravings can be thus copied almost instantaneously, and camera views obtained in one or two minutes on almost any prepa- ration of silver. The common sulphate of copper so- lution has, according to Mr. Flunt, the same property. XL ClIROMATYPE. 54. Many efforts have, been made to render chro- matic acid an active agent in the production of photo- graphs. M. Ponton used a paper saturated with bichromate of potash, and this was one of the earliest photogenic processes. M. Becquerel improved upon this process by sizing the paper with starch previous to the application of the bichromate solution, which enabled him to convert the negative picture into a positive one, by the use of a solution of iodine, which combined with that portion of the starch on which the light had not acted. But by neither of these pro- cesses could clear or distinct pictures be formed. Mr. Hunt has, however, discovered a process, which he has termed chromatype, by which positive pictures THE CHROMATYPE. 51 may very easily be produced. The paper to be pre- pared is washed over with a solution of sulphate of copper, and partially dried; it is then washed with a solution of bichromate of potash, and dried at a little distance from the fire. Papers thus prepared may be kept any length of time, and are always ready for use. They are not sufficiently sensitive for use in the camera, but they are available for every other pur- pose. An engraving, botanical specimens, or the like, being placed upon the paper in a proper photo- graphic copying frame (§ 25), it is exposed to sun- shine for a time, varying with the intensity of light from five to fifteen or twenty minutes. The result is generally a negative picture. It is now to be washed over with a solution of nitrate of silver, which imme- diately produces a very beautiful deep orange picture upon a light dim coloured, or sometimes perfectly white ground. This picture must be quickly fixed, by being washed in pure water, and dried. With regard to the strength of the solutions, it is a curious fact, that, if sa- turated solutions be employed, a negative picture is first produced, but if the solutions be diluted with three or four times their bulk of water, the first action of the sun's rays darkens the paper, and then a very rapid bleaching effect follows, giving an exceedingly faint positive picture, which is brought out with great deli- cacy by the silver solution. It is necessary that pure water should be used for the fixing, as the presence of any muriate damages the picture, and here arises another pleasing variation of the chromatype. If the positive picture be placed in a very weak solution of common salt, the images slowly fade out, leaving a faint negative outline. If it now be removed from the saline solution dried and again exposed to sunshine, a posi- 52 PHOTOGENIC MANIPULATION. tive picture of a lilac colour will be produced by a few minutes' exposure. Several other of the chromates may be used in this process, but none is so success- ful as the chromate of copper above described. XII. — Anthotype.*" 55. The expressed juice, alcoholic, or watery infu- sion of flowers or vegetable substances, may be made the media of photogenic action, and the discovery of these interesting facts are, as in the former case, due to Sir John Herschel. The papaver hybridum, the double ten-week stock, the rose, guiacum, and many other plants, have given results which, although in a practical point of view almost useless, tend neverthe- less to the explanation of facts which were heretofore somewhat obscure. Thus, the flowers which, im- bued with the principle of vitality, whatever that may be, resist the influence of all exterior agents, bud, bloom and flourish in beauty and fragrance, become subject, when the vital energy is exhausted, to these very influences, especially to that of light ; the colour vanishes or is changed ; in fact a photogenic process has taken place. It has long been known, ahhough the reason was not understood, that plants excluded from light have not their natural colour, odour, nor flavour; they make little or no charcoal in the woody part, the leaves are not green, and if they do flower and bear fruit, which is rarely the case, the flowers are pale and scentless, and the fruit insipid. This has been proved by many experiments, of which the bleaching of celery and endive by earthing up, and that of a cab- bage by the natural process of hearting, are familiar * From avdos, a flower, and rvTrog, a picture. AMPHITYPE. 53 examples. A geranium, placed in a dark room, be- comes first pale, then spotted, and ultimately white; and if brought to the light, it again acquires its colour. The knowledge of this fact, and the discoveries conse- quent thereon, have shown us the important influence exerted by the sun's rays on the vegetable world. Seed is placed in the earth ; it is buried in darkness ; under the influence of terrestrial heat and moisture it germinates, and a plant springs into daylight. It has been found that the influence of the most luminous rays, the yellow rays, even on the surface, is suffi- cient to prevent germination ; and on the contrary, that the blue rays forward very remarkably this pro- cess. Plants in all conditions of their growth, absorb by their leaves and bark atmospheric air, which is invariably contaminated with carbonic acid, produced during the processes of respiration and digestion by animals, and poured out in great abundance by all burning bodies. During the sunshine this carbonic acid is decomposed by the plant ; one of its constitu- ents, oxygen, is given off again to the air, while the carbon is retained by the plant, and contributes to the formation of the woody structure. XIIL — Amphitype.* 56. The last process we have to describe in this portion of the work, is one recently made public by Sir John Herschel, and to which he has given the above name from the fact that both negative and positive photographs can be produced by one process. The positive pictures obtained by the process have a perfect resemblance to impressions of engravings with * From ujjKpi, both, and tvttos, a picture. 5* - 54 PHOTOGENIC MANIPULATION. common printer's ink. The process, although not yet fully carried out, promises to be of vast utility, for which reason we deem it better to subjoin it in the words of its discoverer.^' " Paper proper for producing an amphitype picture may be prepared either with the ferro-tartrate or the ferro-citrate of the protoxide or the peroxide of mer- cury, or of the protoxide of lead, by using creams of these salts, or by successive applications of the nitrates of the respective oxides, singly or in mixture, to the paper, alternating with solutions of the ammonio- tartrate or the ammonio-citrate of iron, the latter solutions being last applied, and in more or less ex- cess, i purposely avoid stating proportions, as I have not yet been able to fix upon any which certainly succeed. Paper so prepared and dried takes a nega- tive picture, in a time varying from half an hour to five or six hours, according to the intensity of the light; and the impression produced varies in apparent force from a faint and hardly perceptible picture, to one of the highest conceivable fulness and richness both of tint and detail, the colour in this case being of a superb velvety brown. This extreme richness of effect is not produced except lead be present, either in the ingredients used, or in the paper itself. It is not, as I originally supposed, due to the presence of free tartaric acid. The pictures in this state are not permanent. They fade in the dark, though with very different degrees of rapidity, some (especially if free tartaric or citric acid be present) in a few days, while others remain for weeks unimpaired, and require whole years for their total obliteration. But though * Read before the British Association, Sept. 3i, 1844. AMPHITYFE. 55 entirely faded out in appearance, the picture is only , rendered dormant, and may be restored, changing its character from negative to positive, and its colour from brown to black (in the shadows) by the foliov/- iog process: — A bath being prepared by pouring a small quantity of solution of pernitrate of mercury into a large quantity of water, and letting the sub- nitrated precipitates subside, the picture must be im- mersed in it (carefully and repeatedly clearing off all air bubbles), and allowed to remain till the picture (if any where visible) is entirely destroyed ; or if faded, till it is judged sufficient from previous experience ; a term which is often marked by the appearance of a feeble positive picture, of a bright yellow hue, on the pale yellow ground of the paper. A long time (several weeks) is often required for this, but heat accelerates the action, and it is often complete in a few hours. In this state the picture is to be very thoroughly rinsed and soaked in pure warm water, and then dried. It is then to be well ironed with a smooth iron, heated so as barely not to injure the paper, placing it, for better security against scorching, between smooth clean papers. If then the process have been successful, a perfectly black positive pic- ture is at once developed. At first it most commonly happens that the whole picture is sooty or dingy to such a degree that it is condemned as spoiled, but on keeping it between the leaves of a book, especially in a moist atmosphere, by extremely slow degrees this dioginess disappears, and the picture disengages itself with continually increasing sharpness and clearness, and acquires the exact effect of a copperplate en- graving on a paper more or less tinted with a pale yellow. I ought to observe, that the best and most 53 PHOTOGENIC MANIPULATION. uniform specimens which I have procured have been on paper previously washed with certain preparations of uric acid, which is a very remarkable and powerful photographic element. The intensity of the original negative picture is no criterion of what may be ex- pected in the positive. It is from the production, by one and the same action of the light, of either a posi- tive or a negative picture according to the subsequent manipulations, that I have designated the process, thus generally sketched out, by the term mnphitype, — a name suggested by Mr. Talbot, to whom I com- municated this singular result ; and to this process or class of processes (which I cannot doubt when pur- sued will lead to some very beautiful results) I pro- pose to restrict the name in question, though it applies even more appropriately to the following exceedingly curious and remarkable one, in which silver is con- cerned. At the last meeting \ announced a mode of producing, by means of a solution of silver, in con- junction with ferro-tartaric acid (§ 52), a dormant picture brought out into a forcible negative impression by the breath or moist air. The solution then de- scribed, and which had, at that time, been prepared some weeks, I may here incidentally remark, has retained its limpidity and photogenic properties quite unimpaired during the whole year since elapsed, and is now as sensitive as ever, — a property of no small value. Now, when a picture (for example an im- pression from an engraving) is taken on paper washed with this solution, it shows no sign of a picture on its back, whether that on its face be developed or not ; but if, while the actinic influence is still fresh upon the face {i, as soon as it is removed from the light), the hack be exposed for a very few seconds to the AMPHITYPE. 57 sunshine, and then renaoved to a gloomy place, a positive picture, the exact complement of the nega- tive one on tlie other side, though wanting of course in sharpness if the paper be thick, sloivly and gra- dually makes its appearance there, and in half an hour or an hour acquires a considerable intensity. I ought to mention that the ' ferro-tartaric acid' in question is prepared by precipitating the ferro-tartrate of ammonia (ammonio-tartrate of iron) by acetate of lead, and decomposing the precipitate by dilute sulphuric acid. When lead is used in the preparation of Amphi- type paper, the parts on which the light has acted are found to be in a very high degree rendered vxiter- proof. 57. In the preceding pages we have attempted to furnish the reader with the most remarkable and the most interesting photographic processes as applied to paper. We have purposely omitted a few, for the reason that they were but modifications of other pro- cesses, and their use was attended with no practical advantage. The full details respecting Daguerreotype, Thermography, (fee, will be found so the Second Part of this MannaL I N D E X. Alchemists, Photographic pro- cess of, § 3. Amphitype, Herschel's process of, § 56. Anthotype, process of, § 55. Apparatus for DistiHing Water, § 17, Artificial Light, § 42^ Blotting Paper, § 18. Bromide Paper, § 23. Brushes, § 16. Calotype, Announcement of, § 35. Bringing out, § 40. Fixing of, § 41. Materials necessary for practice of, § 36. Paper, exposure of in Camera, § 39. Paper, preparation ofj § 37. Pictures, transference of, §43. Pictures rendered trans- parent, § 44. Camera, Photogenic, § 33. French, ib. Knight's, ib. Claudefs, ib. Voigtlander's, iK Chromatype, process of, § 54. Chrysotype, process of, § 51. QDlouring Photographs, § 47, Concluding Remarks, § 57. Cooper, Photographic paper ofj § 21. Copper, Sulphate of, brings out Photographs, § 53. Cundell on Lenses, § 34. on Iodized Paper, 37. Daguerre, Photographic Paper of, § 22. Daguerreotype, Purchase of, by French Government, §a ^ Davy, Experiments of, on Pho- tography, § 5. Distilled Water, § 17. Energiatype, process of, § 53, Fixing of Photographs, § 27. Hyposulphite of Soda for, § 28, Calotypes, § 41. Fulhame, Mrs., Photogenic ex- periment of, § 4. Grove, Professor, Method of obtaining positive Calo- types by, § 48. 60 INDEX. Conversion of Negative to Positive Calotypes by, § 49. Herschel, Sir John, Amphi- type, process of, § 56. Chrysotype, process of, §51. Herschel, Sir John,Cyanotype, process of, § 52. Hunt, Mr. Robert, Chroma- type, process of, § 54. Energiatype, process of, §53. Hyposulphite of Soda, Fixing of Photographs by, § 28. Introductory Remarks, § 1, Iodide of Potassium, Fixing of Photographs by, § 27. Iodized Paper, Cundell on, § 37. Mitchell on, § 45. Preparation of, § 37. Ryan on, § 45. Iron, effects of Sulphate of, on theSalts ofSilver,§53. j Knight's Camera, § 33. Lenses for Cameras, § 34. Light, Influence of, on Ani- mals, §11. Inorganic World, § 10. Plants, § 11. Undulatory Theory of, § 12. , Paper for Photographs, § 15. I Blotting, § 18. Paper, Bromide, § 23. Photography, Davy's and Wedgwood's experi- ments on, § 5. Application of, § 31. Photographic Paper, § 20. Precautions necessary in preparation of, § 24. Drawing, § 25. Wood engraving, § 32, Photographs, Colouring of, §47. Dormant, developed by moisture, § 52. Fixing of, § 27. Negative converted into positive, § 49. Objects for, § 26. Rendered transparent, § 30. Printing, Photogenic, § 50, Scheele, Discovery of, § 4, Soda Hyposulphate, § 28, Silver, Nitrate of, § 19. Talbot, Calotype process ofj § 35. Announcement of, § 7. Photographic Paper of, § 20. Voigtlander's Camera, § 33. Nitrate of Silver, § 19. Wedgwood, Mr., Experiments of, § 5. MANIPULATIONS SCIENTIFIC ARTS. PART IV. PHOTOGENIC MANIPULATION. PHOTOGENIC manipulation: PiiHT SI- CONTAINING THE THEORY AJJD PLAIN INSTRUCTIONS IN THE ART OF PHOTOGRAPHY, OR THE PRODUCTION OF PICTURES THROUGH THE AGENCY OF LIGHT. COMPRISING DAGUERREOTYPE, THERMOGRAPHY, ELECTRICAL AND GALVANIC IMPRESSIONS. BY GEORGE THOMAS FISHER, Jun. ASSISTANT IN THE LABORATORY OF THE LONDON INSTITUTION, JJllustrateti mooti dCuts. PHILADELPHIA: CAREY AND HART. 1845. CONTENTS. PAGE. I. — Daguerreotype - - - - - 7 Cleaning' and Polishing the Plates - - 9 The Finishing Powder - - - - 11 Applying- the Sensitive Coating - - 12 Accelerating Solutions - - - - 15 Bromine Water - - - - 16 Chloride of Iodine - - - - - 16 Bromide of Iodine - - - - 17 Chloride of Bromine - - - - 17 Knight's Sensitive Solution - - - 17 Submitting the Plate in the Camera - - 18 Rendering the Picture visible - - - 19 Fixing the Picture - - - - 20 Covering with film of Gold - - . 22 Colouring Daguerreotypes - - - - 23 Paper Daguerreotypes - - . . 25 Durability of Photographic Impressions - - 28 Etching Daguerreotypes - - - - 30 II. — Actino-Chemistry - ... 32 III. — Thermography - - - - - 35 Paper Thermographs - - . - 41 IV. — Electrical Impressions - - - - 42 Galvanic Impressions - - - - 45 Conclusion - - - - - 45 Index 47 PHOTOGENIC MANIPULATION. PART II. I. — Daguereeotype. 58. In the first portion of this treatise we have spoken at length of all the photogenic processes appli- cable to paper, and it remains for us, in this second part, to describe fully and accurately the Daguerreotype and its manipulation. And in order to render this little manual more complete, the mode of procuring impres- sions, which appear identical in character with those obtained by the action of light on paper and metal, but which are dependent on heat arid electricity for their existence, is described in the latter part of the work. 59. We come then first to the consideration of that beautiful process of Photogenic Manipulation, known as the Daguerreotype, so called from its discoverer, M. Daguerre, who, together with Niepce, were liberally rewarded by the French Government, as before mentioned in our Introductory Remarks (§ 8) ; this exquisite art was thrown open to the world, — France taking to herself " Ike glory of endowing the toorld of science mid art with one of the most sur- prising discoveries that honour the land M. Arago 8 PHOTOGENIC MANIPULATION. shortly after, in the Chamber of Deputies, styling it " a gift to the whole worlds 60. Nevertheless, the Daguerreotype has been pa- tented in this country. Whether such patent would stand investigation, is a question not yet proved. Certain it is, that if England be excluded from its free use, France must be content to resign the laurels otherwise her due. 61. The Daguerreotype differs essentially from the other processes of the photogenic art, inasmuch as the production of the image is effected on plates or surfaces of silver ; in other words, silver plated on copper ; the silver employed should be as pure as possible ; the thickness of the two metals together need not exceed that of a card, the silver being of sufficient substance to bear the cleaning and polish- ing is all that is required. 62. To practise the Daguerreotype with success, requires only a little patience and a due attention to the directions subsequently given. The entire process is comprised in six distinct operations ; which may be thus briefly enumerated — 1. Cleaning and polishing the plate. 2. Applying the sensitive coating. 3. Submitting the plate to the influence of light in the camera. 4. Bringing out the picture : in other words, ren- dering it visible. 5. Fixing the image, so that the light no longer acts upon it. 6. Covering the finished picture with a film, or thin coating of gold, which not only protects it, but greatly improves its distinctness and tone of colour. CLEANING AND POLISHING THE PLATE. 9 These processes we shall now fully explaio ; and we shall endeavour to do so as simply as possible, at the same time entering into all requisite detail ; and we would impress upon our readers the necessity of proceeding with patience through each different opera- tion^ which, after a little practice, will be found very easy, while, if they be not attended to, failure will inevitably be the result. And here we may observe also, that it is of the utmost importance to procure good and well-manu- factured plates, as, should there be any imperfection in them, no pains or care taken in the polishing will be of the slightest avail. 63. 1st Operation ; Cleansing a7td Polishing the Plale. — In some of the Daguerreotype establishments the plates are polished in a lathe, — this method having the advantage of being more expeditious ; but the amateur, for whom this little treatise is principally intended, can seldom resort to this plan. The appa- ratus and materials he will require for the operation are the following : — Plate-holder, Spirit-lamp, Stand for supporting the plate, One or two polishing-buffs, Finest washed emery, Olive-oil, French tripoli,— or, in its absence, finely-powdered rotten-stone, free from all grit. Nitric acid, diluted with fifteen parts of water. Finishing powder. And a quantity of the finest carded cotton wool. This should be carefully excluded from all dust and dirt. 10 PHOTOGENIC MANIPULATION. Figs. 6 and 7 represent two forms of plate-holders or instruments for supporting the plate, while being Fig. 6. Fig. 7. cleaned and polished. Fig. 6 is the French pattern. It consists of a flat board, a trifle smaller than the plate, so as to allow the edges of the latter to pro- ject about one-sixteenth of an inch all round. The plate is secured by two small pieces of brass, one of which is movable, and fixed by a screw attached to the opposite angles of the board. It is provided with a handle, by which the whole is conveniently held in the hand. In place of a handle a small clamp is sometimes substituted, by which it may be fixed to a table. Fig. 7 is another very ingenious, and at the same time simple and efficient, plate-holder. It con- sists of a block of wood, somewhat in the form of a dice-box, on one end of which is fixed a piece of Indian rubber, the surface of it being melted by apply- ing to it a hot iron. This renders it permanently adhesive, so that the back of the plate, when pressed against it, adheres firmly ; at the same time, when re- moved by a little force, the back is left perfectly clean. The amount of cleaning a plate requires, greatly depends upon the state it is in. We will suppose one in the worst condition- — not only dirty, but with scratches and mercury-spots on its surface ; and this latter is an accident which very frequently occurs. The plate is placed horizontally on its stand, with its silvered side upwards, and the flame of the spirit-lamp applied, being more particularly directed beneath the mercury-spots, which will soon exhibit a dull appearance. The lamp FINISHING POWDER. 11 is now removed, and the plate allowed to cool, when it is attached to the plate-holder. The readiest method of removing the scratches, is to have recourse to the emery and oil. Holding the plate-holder firmly in the left hand, take a small knot or pellet of cotton, with a little oil and emery, and rub the plate over with a con- tinuous circular motion, till all traces of scratches are removed ; then wipe off the oil and emery with a clean piece of cotton, adopting a light circular motion ; at the same time wiping the edges of the plate. Even the back should not be entirely neglected, but for this a small piece of fine emery paper will be found very convenient. Now mix, to the consistence of thick cream, some of the tripoli with the dilute nitric acid. It is convenient to keep this ready for use in a bottle with a glass stopper. Then take a pellet of cotton, and well polish the plate with this mixture, in the same manner as with the oil and emery ; the process must be continued till, on removing the tripoli with a clean pellet, the plate exhibits a smooth bright surface, free from all spots or scratches. The finishing polish is now to be given with the buff and finishing powder. The buff is formed of a piece of wood, about nine inches long, and from two and a half to three inches broad, slightly convex from end to end. This is co- vered with cotton velvet, being first padded with some soft flannel. A handle may be fixed at one end. 64. The Finishing Powder, — -This is prepared by well calcining lamp-black and intimately mixing it with about an eighth part of the finest rouge (plate powder). This should be kept for use either in a muslin bag, or wide mouthed bottle, over which is tied a piece of muslin ; a little of the powder being dusted on to the buff, the plate receives its final 12 PHOTOGENIC MANIPULATION. polish ; the circular motion is changed for a straight one across the plate, which, if intended for a portrait, should be buffed the narrow way ; but if for a view, the length way of the plate. The operation of clean- ing the plates at first appears very .tedious, and has deterred many from attempting this interesting art ; but it is much more simple in practice than in de- scription, and with a little patience and observation all difficulties are readily overcome. Great care should be taken to keep all extraneous matter from the buff, and when not in use it is better to wrap it up in some tissue paper. The plate should be buffed immediately before the sensitive coating is given (the next process to be described) ; particles of dust are thus effectually removed; the temperature of the plate is also slightly elevated by the friction, and the required tint is more readily obtained. 65. 2d Operation ; Applying the Sensitive Coat- ing, — The apparatus and materials required, are an Iodine box (which, however, is sometimes dispensed with), A bromine pan. Iodine, Bromine, or other sensitive mixture. In the early days of the Daguerreotype, iodine alone was used in preparing the plate ; and though it still plays a very important part, other preparations are used, called accelerating solutions, the discovery of which has alone enabled us to apply the Da- guerreotype successfully to portrait-taking. For whereas, when first described by Daguerre, it took from five to ten minutes to produce a tolerably good view ,• now, under favourable circumstances, splendid impressions can be obtained in tlic fraction of a second. APPLYING THE SENSITIVE COATING. 13 li the plate is to be iodized, it must be placed, im- mediately after being buffed, in the iodine box. This consists of a square box, which may be made of any hard wood, and lined with common crown glass ; small frames of wood suited to the different sized plates are made to fit on the top, and over them rests the lid. The box may be about two inches deep. Some iodine is scattered evenly over the bottom, and covered with a piece of cotton wool ; over this is sometimes placed a piece of card. The plate being dropped into the frame with its face downwards, the lid is put on, the bright surface of the plate is very soon coated with a film of iodine of a fine yellow colour; it is then removed and placed over the accelerating solution. The iodine operation need not be done in the dark, though a bright light should be avoided. Not so the next part of the process, viz., giving the plate its extreme sensitiveness : here great caution to prevent the slightest ray of light impinging directly on the plate must be used, and in examining the colour reflected light should always be used. A convenient method of examining the plate is to make a hole about one inch square in the window shutter^ which is then covered with a piece of tissue paper ; by quickly turning the plate so that the paper is re- flected on to it the colour is very distinctly shown. The key-hole of a door, where there is a light on the outside, will frequently answer the purpose. 66. Various have been the different forms and con- trivances suggested for the bromine pan, or vessel in which the sensitive mixture is applied ; we shall de- scribe three, each of which has its advantages. Fig, 8. represents an earthenware or glass pan; and here we may observe, that the bottoms of all 2 14 PHOTOGENIC MANIPULATION. these vessels should be as flat as possible, so as to allow the solution to be of an equal depth ; the edge is ground flat, by which means a piece of roughened plate glass fits air-tight, and this may be fixed inside Fig. 8. a wooden cover. In the centre of the under side of the glass lid, is cemented a small block of wood, to which is attached a piece of sheet Indian rubber, the surface of which is pre- pared as described for the plate-holder (Fig. 7); the plate is then attached to it in a similar manner. When not in use, a glass cap is ])laced over the Indian rubber, which effectually prevents any action going on between the vapour from the solution and the Indian rubber. Fig. 9. represents another form of apparatus ; it consists of a porcelain pan, which may either be square or round ; its edge is ground flat, and it is provided with a ground glass cover fitting it air-tight. About three-eighths of an inch below the top is a ledge, on which rests a shelf, B, made either of hard wood, slate, or glass ; in the centre of this a square hole is formed, with a shoulder, in which the Daguerreotype plates rest during the time they are submitted to the action of the sensitive solution contained in the pan. Fig. 10, represents the last form of bromine pan Fig. 9. APPLYING THE SENSITIVE COATING. 15 which remains for us to describe; it is, in our opinion, the most convenient of the three. Fig. 10. A, is a square glass vessel about three or four inches deep, and of sufficient size to receive the largest plate required ; the edges are ground perfectly smooth, and it is provided with a cover of plate glass, B, which fits it accurately, and effectually prevents any escape of the bromine, or other accelerating solution con- tained v^^ithin it, C represents a second lid, made either of a piece of slate, ground perfectly flat, or plate glass; in the centre is cut out a square hole, the size and form of the plate, with a shoulder similar to the one last described, on which the plate rests; the edge of C being placed against that of B, the lat- ter is gradually slid away, the former occupying its place, and exposing the plate to the vapour without allowing any to escape. The changing colour of the plate may be viewed through the side of the glass, which is polished for the purpose, and when it has remained the proper time, the lid B is slid on again in the same manner, without having once opened the glass. The whole may be enclosed in a frame of wood, which greatly facilitates the sliding away of the lids. 67. The Accelerating Solutions. — These differ 16 PHOTOGENiC MANIPULATION. both in composition and action, some acting very quickly, others giving a finer tone of colour, though they are not so expeditious in their operation, that is to say, not so sensitive to the action of light. They are all applied in a similar manner, and the glasses or pans we have described are applicable to all. 68. Bromine Water. — This solution has been much used in France, and we shall therefore give its preparation and the method of using it, in the words of M. Figeau. ''Put into a bottle of pure water, a large excess of bromine ; shake the mixture well, and before using it, let all the bromine be taken up." An ascertained quantity of this saturated water is then diluted in a given quantity of distilled water, which gives a solution of bromine that is always iden- tical. M. Figeau recommends one part of the satu- rated solution to thirty parts its bulk of water ; but M. Lerebour finds it more manageable if diluted with forty times. In case pure distilled or rain water can- not be procured, a few drops of nitric acid, say six to the quart, should be added to the common water. Method of 2tse.—?\ii into the bromine pan a given quantity of the bromine water, sufficient to well cover the bottom : the plate having been iodized to a deep yellow is placed over it ; the time the plate should be exposed must be ascertained by making a few trials ; it averages from twelve to forty seconds. When once ascertained, it is the same for any number of plates, as the solution, which of course would become weaker and weaker, is changed after every operation, the same quantity being always put into the pan. 69. Chloride of Iodine* — This is prepared by in- troducing into a glass vessel containing iodine, chlo- rine gas ; the iodine is liquefied, and the above-named knight's sensitive solution. 17 compound is the result. This is diluted with distilled water, and the plate submitted to it in the bromine pan till it is of a rose colour. 70. Bromide of Iodi7ie,—MdiVe a solution of iodine in alcohol, into which add, drop by drop, bromine, till the solution is of a bright red colour. This is then diluted with water till the colour is reduced to a bright yellow. It is used in a similar manner as the before-mentioned preparations. 71. Chloride of Bromine, — Bisson, a French experimentalist, has found that bromine associated with chlorine, prepared in a similar manner to the chloride of iodine described before (§ 69), a solution of bromine being substituted for the iodine, is a very sensitive solution. By means of it Daguerreotype proofs are obtained in half a second, and thus ver}^ fugitive subjects are represented — for instance, the smile of an infant, a funeral train, nay, even men and horses in the act of walking. 72. The publishers of this little work have a pre- paration which they sell under the name of Knight's Sensitive Solution, which is used without the plate being previously iodized. Though it does not act quite so quickly as some of the other preparations, it gives a beautiful tone of colour to the Daguerreo- types. The method of using it is as follows: — a sufficient quantity of water is poured into the bromine pan as will well cover the bottom. This quantity being then measured, 39 drops of the solution are added to every half ounce of water; a violent action takes place, and iodine is precipitated ; the plate is exposed till it attains a rose colour. 73. The only other solution that we shall mention is the Hungarian Liquid, the composition of which is 2* 18 PHOTOGENIC MANIPULATION. not generally known. It is a very favourite mixture, acts quickly, and with considerable certainty. The method of using is, to dilute it with from 10 to 15 times its bulk of water, putting a sufficient quantity into the pan to cover the bottom. The plate being previously iodized to a light yellow, it is submitted to the Hungarian mixture till it attains to a light rose tint. 74. The processes we have been describing are, as we have before stated, carried on in the dark ; and great caution must be used in examining, even by the feeble light (§ 65) allowed the colour of the plates, which, when attained, the plate is to be immediately placed in one of the dark fram.es belonging to the camera. 75. 2d Operation; Suhmitling the Plate to the Influence of Liglit in the Camera. — Experience alone will guide the operator as to the time the plate must be exposed to the action of the light, this being dependent on a variety of circumstances, as clearness of the atmosphere, time of the day, object to be taken, and degree of sensitiveness of the solution which has been employed, &c. He should be careful to see that the interior of the camera is clean and free from dust, for the small particles flying about attach them- selves to the plate, when the slide is removed, and thus cause the little black spots, by which an other- wise good picture is frequently spoiled. Care should likewise be taken to withdraw, as gently as pos- sible, the dark slide in front of the plate, so as not to set any of these particles, which might be at rest, in motion. The lens is the last thing to be uncovered. When, according to the judgment or experience of the operator, the plate has remained long enough, the RENDERING THE PICTURE VISIBLE. 19 cap is replaced on the lens, and the dark slide over the plate, which is then renaoved from the camera. If now examined, no picture will be found on the plate. The rendering this visible is the object of the next process. 76. Ath Operation. — Brwging out the j)icture^ in other ivords^ rendering it visible, — The only appa- ratus required for this is the mercury box. Fig. 11 represents one of a very convenient con- struction. The box is of wood, of the form repre- sented in the figure. The bottom is made of sheet- iron, slightly dished in the centre ; this is for contain- ing a small quantity of mercury. The bulb of the stem being Fig. 11. bent in thermometer dips into this, the such a manner that the scale comes outside the front of the box, the mercury being heated by the spirit-lamp. The ther- mometer indicates to the opera- tor the temperature obtained. The plates are supported in a groove, placed for the pur- pose, inside the lid. This pro- cess is usually carried on in a dark room ; but the box may be so contrived as not to ren- der this necessary, the dark frame fitting the camera, and containing the plate, being made so as to adapt itself to the top of the mercury-box, so that when placed in, the slide may be withdrawn as in the camera. When required to be very portable, the legs are made to fold beneath the box. It is a very convenient plan, especially in travelling, to tie up the mercury in a 20 PHOTOGENIC MANIPULATION. piece of muslin : it can be placed just as readily over . the bulb of the thermometer, and answers equally well. The temperature should never be raised above 170° Fahrenheit. The plate may be examined, from time to time, by simply raising the lid of the mercury- box, and viewing it by a subdued light. Some boxes are fitted up with a small window of yellow glass (§ 88) for this purpose, but it is unnecessary. Mr. Constable, the proprietor of the photogenic establish- ment at Brighton, a most successful operator, has contrived a very useful sliding scale,* by which, at a single glance, the operator may at once see the time the plate should be exposed to the mercury, regulated by the temperature both of the apartment and mercury. The picture, being fully developed, is now taken out and examined : it must not, however, be exposed to too strong a light : if any glaring de- fect be perceived, it is better not to proceed with it, but place it on one side, to be repolished : if, on the contrary, it appear perfect, we may advance to the next step. 77. bth Operation, — Fixing the imo.ge^ so that the light no longer acts upon it. — For this the following are required : — Two or three porcelain vessels, for small plates, the form is not material, and evaporating-dishes answer very well ; but for large plates the form A, Fig. 12, will be found most convenient. Plate support B. Pair of pliers. A drying apparatus, Fig. 13, is also convenient; though, for small plates, it can be dispensed with. Hyposul2')hite of Soda^ — Distilled Water^ and * The scales may be obtained of the publishers. HYPOSULPHITE OF SODA. 21 some contrivance for heating it. — Having made a solution of hyposulphite of soda, the strength is not material, (about half an ounce of the salt to the pint of distilled water,) pour it into one of the porcelain vessels, put into another plain, and into a third dis- tilled water. The plate being immersed with its face upwards in the hyposulphite, the whole of the sensi- tive coating is immediately removed. The light has now no further action upon the plate : it is then to be removed from the hyposulphite and immersed in the plain water, or placed on the support B, Fig. 12, and water poured over it. It is then washed in a similar man- ner with distilled water, and well examined, to see that not the slightest particle of dust rests on the surface. We now proceed to dry it. 78. Fig. 13 represents a convenient and simple apparatus for the purpose. A is a vessel of sufficient size to take the largest plate, but not more than half an inch wide: it is best made of copper or brass, tinned or plated inside, which must be kept perfectly clean. Hot distilled water is poured into it, and the temperature kept up by the spirit-lamp. The plate supported by the holder c is immersed, and then gradually withdrawn ; at the same time the operator should gently blow upon the surface: it may, by this Fig. 12. 22 PHOTOGENIC MANIPULATION. 1 Fig. 13 c a method, be brought out perfectly diy. Small plates are readily dried, by holding them with the pliers by one corner, and pour- ing distilled water over them (if the water is hot it will be all the better). Apply the spirit-lamp to the back, at the corner held by the pliers, at the same time facilitating the operation with the breath ; pass the lamp gra- dually downwards, finishing at the extreme corner. The last drop may be removed by a little bibulous paper ; a single drop even of dis- tilled water allowed to dry on any part of the surface is certain to leave a stain, which no ultimate process can remove. The Daguerreotype may now be said to be finished ; still it is so much improved by the sixth and last pro- cess, that it can hardly be considered complete with- out it. 79. 6fJi Operation — Covering the finished picttire v;ith a film or thin coating of gold, — This process, for which we are indebted to M. Figeau, may take place either before the plate is dried, or at any sub- sequent period of time. The only apparatus required, is the spirit-lamp and stand. The solution of chloride of gold is thus prepared : — Dissolve, in a pint of dis- tilled water, 15 grains of crystallized chloride of gold ; the solution will be of a golden tint. In another pint of distilled water dissolve 45 grains of hyposul- phite of soda ; pour gradually, in very small quanti- ties, the gold into the hyposulphite, stirring the solu- tion at intervals ; when finished, the mixture should COLOURING DAGUERREOTYPES. 23 be nearly colourless. Place the plate on its stand in a perfectly horizontal position, and with its edges quite free; wet the surface with alcohol, letting any superfluous quantity drain off. Now pour on, care- fully, as much of the preparation of gold as will remain on the plate. The alcohol is of no further use than to facilitate the flowing of the gold mixture over the surface. The under part of the plate is now to be heated as uniformly as possible with the spirit-lamp. Small bubbles will rise, and the appearance of the view, or portrait, will very visibly improve ; the pro- cess must not be carried too far, but as soon as all the bubbles disappear, the lamp should be removed, and the fluid poured ofl* the plate immersed in dis- tilled water, and dried by the method described be- fore (§ 78). 80. Colouring Daguen-eotypes, — Neither the Da- guerreotype, or any other photogenic process, has yet arrived at that state of perfection as to enable us to represent objects in their natural colours. Various beautiful tints are frequently obtained, these depend upon different circumstances ; but, hitherto, decided colour is wanting. If we wish for colour we must resort to mechanical means to obtain it. Mr. Beard patented a process*' for colouring Daguerreotypes ; but it is very troublesome, and seldom, if ever, resorted to. The best and certainly the simplest method ap- pears to be the brush, which of course must be very fine. The colours, which are applied in the state of a fine impalpable dry powder, are prepared and sold for the purpose. They should not be applied by any one who is not something of an artist ; and, after all, it is entirely a matter of opinion whether the pencil- lings of nature can be improved by the hand of man. * Repertory of Patent Inventions, April, 1843, 24 PHOTOGENIC MANIPULATION. 81. A very pleasing effect is given to portraits and figures fronn life, and was first suggested by Mr. Ciaudet. It consists in the introduction of appro- priate back-grounds, by sinnply placing the sitter in front of a painting, or rough sketch of a landscape, the interior of an apartment, &c. This adds very much to the interest of the picture, which otherwise is frequently dull, cold, and inanimate. 82. The following are a few hints, which may be useful to the experimentalist. The glasses of the camera should be perfectly clean. We have before alluded to the necessity of removing all dust from this instrument (§ 75). The camera should never be so placed that the sun shines into the lenses. If a por- trait is to be taken, the sitter should be placed with bis head resting against something, no matter how slightly, but just sufficient lo keep it perfectly steady. The eyes should be fixed on some object a little above the camera, arid care should be taken that the hands and feet, in whatever position, are not too forward or backward from the face when that is in good focus. If any large surface of white is present, such as a shirt-front, lady's collar, handkerchief, &c., a piece of black stuff should be thrown over it, and quickly withdrawn, when the process is about two-thirds fieished ; smaller parts of the dress, as the shirt- collar, wristbands, &c., need not be interfered with. The process should be conducted in the open air under a serene sky, but without sunshine. Jf sun- shine be employed, a screen of blue glass should be used to defend the eyes. This coloured glass does not materially weaken the power of the chemical rays (§ 12). The best of all situations is a raised terrace, or the fiat roof of a house. Of all weather a damp state of the atmosphere is to be avoided,. PAPER DAGUERREOTYPES. 25 83. A ready method of marking short intervals of time is very important to the Daguerreotypist. We will describe an instrument, which will be found very useful for that purpose; it was contrived b^ Mr. Constable, a gentleman we have before had occasion to name (§ 76) ; he calls it a sand-clock, or time- keeper. It consists of a glass tube, about 12 in. long by 1 in. diameter, half filled with fine sand, similar to that used for the ordinary minute-glasses, and like them it has a diaphragm, with a small hole in the centre, through which the sand runs. The tube is attached to a board, which revolves on a centre-pin ; on the side is a graduated scale, divided into half-seconds ; the tube is also provided with a movable index. The instrument is attached to the wall, either of the garden or apartment where the operator requires it. The glass tube being revolved on its centre, the index is set to the number of half- seconds required, and the sand running doAvn, the required time is marked without the possibility of error. In practice, it will be found a far more con- venient instrument for the purpose than either a clock or seconds-watch, and is applicable both for the camera and mercury-box. 84. Paper Dagiierr eoiy pes,— M.r:. Hunt, in his v/ork on the photogenic art, describes therein a method of which he himself was the discoverer, by which the Daguerreotype may be rendered applicable to paper. His description is as follows Placing the paper carefully on some hard body, wash it over on one side, by means of a very soft camel's-hair pencil, wath a solution of 60 grains of bromide of potassium in 2 fluid ounces of distilled water, and then dry it quickly bv the lire. Being drv, it is again to be washed over 26 PHOTOGENIC MANIPULATION. with the same solution, and dried as before. A solu- tion of nitrate of silver (120 grains to an ounce of dis- tilled water) is to be applied over the same surface, and the paper quickly dried in the dark. In this state the papers may be kept for use. When they are required the above solution of silver is to be plentifully applied, and the paper placed wet in the camera, the greatest care being taken that no day- light — not even the faintest gleam— falls upon it until the moment when we are prepared, by removing the screen, to permit the light, radiated from the objects we wish to copy, to act in producing the picture. After a few seconds the light must be again shut off, and the camera moved into a dark room. It will be found, in taking the paper from the box, that there is but a very slight outline (if any) yet visible. Place it aside in perfect darkness, until quite dry ; then place it in the mercurial vapour-box (Fig. 11), and apply a very gentle heat to the bottom. The mo- ment the mercury vaporizes, the picture will begin to develope itself. The spirit-lamp must now be re- moved for a short time, and when the action of the mercury appears to cease, it is to be very carefully applied again, until a well-defined picture be visible. The vaporization must then be suddenly stopped, and the photograph removed from the box. The drawing will then be very beautiful and distinct; but much detail is still clouded, for the developement of which it is only necessary to place it cautiously in the dark, and allow it to remain undisturbed for some hours. There is now an inexpressible charm about the pictures, equalling the delicate beauty of the Daguerreotypes ; but being still very susceptible of change, it must be viewed by the light of a taper only. The nitrate of silver must now be removed from the paper, by well- PAPER DAGUERREOTYPES. 27 washing it in soft water, to which a small quantity of salt has been added, and it should afterwards be soaked in water only. When the picture has been dried, wash it quickly over with a soft brush dipped in a warm so- lution of the hyposulphite of soda, and then well-wash it for some time in distilled water, in order that all the hyposulphite may be removed. The drawing is now fixed, and we may use it to procure positive copies, many of which may be taken from one original. " The action of light on this preparation does in- deed appear to be instantaneous. The exquisite de- licacy of this paper may be imagined, when I state that in five seconds^ in the camera, I have, during sunshine, obtained perfect pictures ; and that, when the sky is overcast, one minute is quite sufficient to produce a most decided effect. " This very beautiful process is not without its diffi- culties ; and the author cannot promise that, even with the closest attention to the above directions, annoying failures will not occur. It often happens that some accidental circumstance (generally a projecting film or a little dust) will occasion the mercurial vapour to act with great energy on one part of the paper, and blacken it before the other portions are at all affected. Again, the mercury will sometimes accumulate along the lines made by the brush, and give a streaky ap- pearance to the picture, although these lines were not at all evident before the mercurial vapour was applied. I have stated that the paper should be placed wet in the camera : the same paper may be used dry, which is often a great convenience. When in the dry state, a little longer exposure is required ; and instead of taking a picture in four or five seconds, two or three minutes are necessary." 28 PHOTOGENIC MANIPULATION. 85. Durahility of Photographic Lnpressions, — Some time since an idea originated, and gained con- siderable ground, to the effect that all photographic impressions, more particularly, perhaps, Daguerreo- types, were not durable. Immediately after the great fire at Hamburgh, M. Bion, a skilful artist, took Daguerreotypes of all the most interesting points of those parts of the town destroyed by the fire, and which were historically valuable. The Historical Society of the town endeavoured to obtain possession of the whole of them, amounting altogether to forty- six photographic impressions. But on the eve of the conclusion of the purchase, one of its members started a doubt as to the durability of these impressions. Might not, it was argued, these productions of the sun's rays be also gradually destroyed by the action of light ; and another generation, eager to form an idea of the destruction occurring at a former period, and reverting to these impressions, discover, with disap- pointment and dismay, that such impressions, once the true picture of a painful reality, with the most distinct and circumscribed outlines, had been con- verted into some dozens of mere unsightly metal plates, covered with black oxide. This opinion was further confirmed by the profes- sor of chemistry. He argued that the substances employed for the production of photographic impres- sions unite so as to form very weak combinations, which may as easily undergo entire decomposition; that the quicksilver which serves for producing these impressions may become the cause of their ultimate destruction, by the amalgamation thereof with the silver plate, and thus the outlines become obliterated or indistinct ; that a polished plate of silver is in a DURABILITY OF PHOTOGRAPHS. 29 short time blackened by the sulphuretted hydrogen gas contained in the atmosphere, and that a photo- graphic impression must be considered as exposed to precisely the same influence and change, and thus, from all these circumstances put together, such im- pressions are in the highest degree perishable. 86. To ascertain whether such opinion was founded in truth, M. Ulex of Hamburgh, undertook a series of experiments, chiefly in relation to Daguerreotypes. In the first place, a Daguerreotype was carefully wrapped in thick bands of paper so as to cover one-half of the impression only. In this state it was hung up so as to afford a direct southern aspect, and when, after an exposure of many weeks, the protecting cover was re- moved, not the slightest difference was observed in the two several halves of the impression. We may add that we are still possessed of one of the earliest Da- guerreotypes, this has been constantly exposed to day- light and the direct rays of the sun, and it is now as perfect as when it was first taken. This goes far to prove that they are but little affected by the action of light. M. Ulex then exposed an impression in the water-bath to the temperature of 167 deg. Fah., with- out its undergoing the least alteration. With regard to the destructive effect of the mercury itself, M. Ulex makes the following observations ; — " If we examine a good Daguerreotype under the microscope, we are unable to distinguish any percep- tible globules of quicksilver; the plate appears punc- tuated or dotted like a chalk drawing. If a silver plate be coated with some leaf-gold, and then brought into the mercury-box, the mercury being heated to 167 deg. Fah., and the plate lefl therein for the space of ten minutes (and to obtain a good photographic 3^- 30 FHOTOGENIC MANIPULATION. impression no longer time is necessary), the gold will still preserve its golden-yellow colour, and this proves how exceedingly slight the quantity of quicksilver- fumes must be which are deposited on the plate. It was ascertained too, some time ago, that an iodized silver plate taken from the camera obscura, and placed for two hours over quicksilver of not more than 54 deg. Fah., yields a perfect and distinct im- pression. The mercury, therefore, would not be able to destroy the impressions." Other photographs were exposed to the action of carbonic acid, ammonia, and even for a short time to the action of sulphuretted hydrogen, without, how- ever, losing in the slightest degree the distinctness of their outline, or being destroyed. A pure silver plate in contact with the air, if only for a short time ex- posed to sulphuretted hydrogen, is rapidly blackened by the action of the sulphuretted hydrogen. If, how- ever, the oxygen of the air be excluded, silver may be kept for a long time in sulphuretted hydrogen without being affected. And if it be remembered that these impressions are almost invariably kept covered with glass, it is almost impossible that they can be de- stroyed. At the present time too, almost all these impressions are gilt, according to the method of Figeau (§ 79). We arrive then, at this result ; that the preference, as regards durability, must justly be given to photo- graphic impressions over paintings in oil, and we may confidently discharge the fear that they will soon un- dergo destruction. 87. Etching Dagicerreotypcs. — Soon after the beautiful photographs of Daguerre became public, attempts were made to engrave or etch the impres- ETCHING DAGUERREOTYPES. 31 sions so produced. Dr. Berres of Vienna was the first to publish a process for etching Daguerreotypes, his process consisted in covering the plates with the mucilage of gum Arabic, and then immersing them in nitric acid of different strengths. In 1841, Professor Grove made known a method of etching Daguerreotypes by means of electricity. The plan he adopted was to make the Daguerreotype the anode of a voltaic combination, in a solution which did not of itself attack either silver or mercury, but which, when electrolized, would act on the metals unequally. The solution used was dilute hydrochlo- ric acid. As this process is fully described in the valuable little manual on Electrotype Manipulation, by Mr. C. V. Walker, we need do no more than merely refer to it. M. Figeau, of whom we have already had occasion to speak, likewise discovered a process for the en- graving of Daguerreotypes ; and founded on the be- lief that the lights of a Daguerrian plate consist of unaltered silver, while the darks or shadows consist of mercury or an amalgam of mercury with silver. He finds that a compoimd acid consisting of a mixture of nitric, nitrous, and muriatic acids, or of nitric acid mixed with nitrate of potass and common salt, has the property of attacking the silver in presence of the mer- cury without acting upon the latter. Bichloride of copper answers the purpose also, but less completel3^ When the clean surface of a Daguerrian plate is exposed to the action of this menstruum, particularly if warm, the white parts or lights are not altered, but the dark parts are attacked, and chloride of silver is formed of which an insoluble coating is soon deposited, and the action of the acid then ceases. This coat of 32 PHOTOGENIC MANIPULATION. chloride of silver is removed by a solution of ammo- nia, and then the acid applied again, and so on, until the depth of hiiing in is sufficient. However, it is not possible, by repeating this process to get a suffi- cient force of impression ; a second operation is re- quired, in order to obtain such a depth as v^^ill hold the ink, to give a dark impression ; for this purpose the whole plate is coated with drying oil ; this is cleaned off with the hand exactly in the way a cop- per-plate printer cleans his plate. The oil is thus left in the sinkings or dark bitten in parts only. The whole plate is now placed in a suitable apparatus, and the lights or prominent parts of the face are gilt by the electrotype process. The whole surface is now touched with what the French engravers call the " Resin Grain," [graine de resine) a species of partial stopping out, and is at once bitten in to a sufficient depth with nitric acid, the gilding preserv- ing the lights from all action of the acid. The resin grain gives a surface to the corroded parts suitable for holding the ink, and the plate is now finished and fit to give impressions resembling aquatint. But as silver is so soft a metal that the surface of the plate might be expected to wear very rapidly, the discoverer proposes to shield it by depositing over its whole sur- face a ver}^ thin coat of copper by the electrotype process ; which when worn may be removed at pleasure down to the surface of the noble metals be- neath, and again a fresh coat of copper deposited ; and so an unlimited number of impressions obtained without injury to the plate itself. II. — Actino-Chemistry. 88. Before concluding this portion of the work, we ACTINO-CHEMISTRY. 33 deem it necessary to make some few remarks relative to the theory recently propounded, by which all these photographic phenomena are supposed to depend upon some secret power, which invariably accom- panies, but is in a great measure independent of, light. This supposed power had received from Dr. Draper the name of Tiihonicity, and from Mr. Hunt that of Energia ; but at the last meeting of the British Asso- ciation at York, it was generally agreed that the name of Actinism,* or Actino-Chemistry, should be substituted, as being less likely to mislead. To explain the experiments which have led to such a conclusion, the annexed wood-cut will enable c * From aKTip, a ray. 34 PHOTOGENIC MANIPULATION. the reader more readily to understand us. It repre- sents the prismatic spectrum, — the colours of the spectrum being represented in their regular order, between the points a and b. We have already said (§ 12) that the violet ray produces the greatest chemi- cal change, vk'hile at the red ray the greatest degree of heat is detected. Under ordinary circumstances no light or colour is detected beyond these limits ; but at B another red ray is discovered, and at a a lavender ray has been observed. The curved line c shows the extent to which the luminous effects of the spectrum extend, the maximum of light being at the yellow ray, from whence it declines till at a and h all light is completely lost. Sir William Herschel found that the greatest heat was given by the rays beyond the visible red rays, and which in the diagram is represented by d, from which spot it declines, until, at the violet end of the spectrum, it is completely lost. At an earlier period of our knowledge, it was believed that the chemical power of the sunbeam was confined to the spaces within and above the blue rays, but the recent researches of philosophers have shown that this influence is far more extensive. The maximum of chemical action is somewhere about e; for if we place a prepared photographic paper in such a posi- tion that a well-defined coloured spectrum shall fall upon it, it will be found to darken with th© greatest rapidity, and acquire the most intense colour at that point ; this darkening will go on upwards, beyond all the visible rays, to where it entirely ceases. It ex- tends downward to the luminous rays c, where a negative influence is exerted, the paper remaining white, after passing which, it again darkens, and a second maximum is found at f, — the red rays usually THERMOGRAPHY. 35 giving a red impression, — this chemical power ceas- ing entirely at e. Here, then, are three distinct phenomena, Light and Colour, Heat, and chemical power, or Actinism. Now, it is argued that Light and Actinism are distinct forces, — for, by reference to the diagram, it will be observed that the largest amount of chemical effect is produced where there is the least light, — and conversely, that where there is the largest amount of light at c, there no chemical effect is observed. Again, by causing a sunbeam to permeate a deep purple solution (copper in ammonia), we deprive it of nearly all its light, — but the chemical, or actinic, effect is not at all diminished. On the other hand, if we take a solution of bichromate of copper, which is of a bright yellow colour, all the light passes it freely, but scarcely any of the chemical principle. Such are the arguments in favour of the existence of three distinct principles in the solar rays; the truth or error of the theory, time and future dis- coveries can alone determine. in. — Thermography. 89. We have deemed it necessary, ere this little work be brought to a conclusion, to notice a process connected in some degree with the art discussed in the preceding pages. For this discovery we are indebted to Mr. Hunt, who has given to it the name of Thermo- graphy.* The process is thus described by him ; — 90. " A well-polished plate of copper is rubbed over with nitrate of mercury, and then well-washed in distilled water to remove any nitrate of copper which may be formed ; when quite dry, a little mer- cury, taken up on soft leather or linen, is well-rubbed on it, and the surface worked to a perfect mirror. * From 0£p//oj heat ; and ypa^w, to write. 36 PHOTOGENIC MANIPULATION. " The print or drawing to be copied is placed smoothly over the nriercurial surface, and a sheet or two of soft clean paper being placed upon it, it is pressed into equal contact with the metal, by a piece of glass or flat board ; in this state it is allowed to re- main for an hour or two. The time may be consi- derably shortened by applying a very gentle heat, for a few minutes, to the under surface of the plate. The heat must on no account be so great as to volatilize the mercury. The next process is to place the metal in a closed box adapted for generating the vapour of mercury (Fig. 11). The vapour is to be slowly evolved, and in a few seconds the picture will begin to appear. The vapour of mercury attacks those parts which cor- respond to the white parts of the printed image or en- graving, and gives a very faithful but somewhat in- distinct image. The plate is now removed from the mercurial-box, and placed in one containing iodine, to the vapour of which it is exposed for a short time : it will soon be very evident that the iodine vapour attacks those parts which are free from mercurial vapour, blackening them. Hence there results a perfectly black picture, contrasted with the gray ground formed by the mercurial vapour. The picture being formed by the vapours of iodine and mercury, is of course in the same state as a Daguerreotype, and is readily de- stroyed by rubbing. From the depth to which I find the impression made into the metal, I confidently hope to be enabled to give to these singular and beautiful productions a considerable degree of permanence, so that they may be used by engravers to work on."* 91. But to produce impressions of Ihis nature, a * Transactions of the Royol Polyteclmic Society, No. f.— Ther- mography, by R. Hunt. Esq, THERMOGRAPHY. 37 process so complicated as that described by Mr. FJunt is not absolutely necessary. Impressions of coins, per- fect even to the minutest detail, may be obtained on metallic plates with much less trouble and in much less time. For this purpose the highly-polished plates employed for the Daguerreotype answer extremely well. The coin from which an impression is required (gold coins are the best for the purpose), should be rendered perfectly clean, and should be smeared with a little sweet-oil, which should subsequently be wiped completely away with a small pellet of cotton. We say completely^ although this is not absolutely the case, for an invisible film of oil adheres to the coin and thus assists in producing the impression. The coin should now be placed carefully on the highly- polished metallic plate, and a gentle heat cautiously applied to the coin or to the plate, so as in fact to render the two metals of a different temperature. A ready method of doing this is to coil a stoutish copper wire into a circular form, so that it may entirely cover the coin. If this wire be now heated and ap- plied to the back of the coin, it will have the requi- site effect of increasing the temperature of the coin itself without injuring the plate. When cold, a more or less perfect impression is the result. 92. In a lecture* delivered in 1843 at the London Institution, Professor Grove expressed his belief that " these impressions were caused by a radiation and condensation of whatever vapour exists between the metals, and which, by being condensed unequally (in the case of different metals by their different conduct- ing and radiating powers), produce an impression ac- cording to the unequal distance of the different parts of * Reported in the Literary Gazette, January 21, 1843. 4 38 PHOTOGENIC MANIPULATION. the stamp on the coin. Thus, for example, taking a sovereign placed on a silver or copper plate, the effect is very visible if the coin be breathed on before being brought into contact ; it is still more increased if the coin be rubbed with oil, and wiped apparently dry ; and it is still further improved if it be held for an instant over the vapour of a substance capable of chemically acting on the juxtaposed plate ; as, for in- stance, over ammonia before being placed on copper. There are other circumstances with regard to these metallic thermographs, which are worthy of remark. Thus when two portions of the same metal are juxta- posed at the same temperature, no effect is produced. When at a different temperature, a slight effect is perceptible. When the metals are different at the same apparent temperature, a greater effect is per- ceptiple ; and further, when both metals and tempera- ture are different, the greatest effect is visible. It occasionally occurs, too, that the impression made is latent, that is to say, it does not become visible until breathed on, or until some vapour is condensed upon the plate. 93. Some curious effects, apparently resulting from the approximation of bodies, had been observed on many occasions, and by different individuals. Pro- fessor Faraday repeatedly noticed the impression of an engraving on the glass, under which it was framed, when separated from the picture. M. Brequet of Paris has recorded a somewhat similar phenomenon; " It is known," he says, " that modern watches are often furnished with a double case (cuvette)^ on one side of which the name of the manufacturer is en- graved. The interstice between occupying, at the utmost, not more than the tenth of a millemetre. THERMOGRAPHY. 39 Now, I observed frequently on the inside of the plain half, a reversed but very distinct image of the name, as engraved on the other. I have observed, too, on different parts of machines, arranged very near each other, that they presented more or less dis- tinct representations of marks placed on the opposing parts.'' These phenomena are in every way ana- logous to those we now know under the name of Thermographs. An analogous fact was also observed by a philoso- phical instrument maker. Monsieur Oertling, in grind- ing parallel glasses. The brass plates, which were ^ placed immediately over the glasses and attached to their side by cement, were provided for a certain pur- pose with circular furrows. Some of theglasses treated in this manner afforded images of these furrows ; but in most cases the eye was incapable of distinguishing the least spot ; if, however, they were breathed upon, the image appeared with great distinctness, and thus those parts which were in contact with the brass ap- peared of a darker tinge. This peculiarity could not be removed from the glasses by washing with spirits of wine or oil of turpentine ; but required a repetition of the grinding. 94. iProfessor Moser, whose researches on this subject have added much to our knowledge of these interesting phenomena, makes the following state- ments in reference to them : — All bodies radiate light even in complete darkness. This light does not appear allied to phosphore- scence, for there is no difference perceived, whether the bodies have been lon^r in the dark, or whether they have been just exposed to daylight, or even to direct solar light. 40 PHOTOGENIC MANIPULATION. The rays emanating from different bodies act as light. Two bodies constantly impress their images on each other even in complete darkness. In order, however, that the image should be appre- ciable, it is necessary, because of the divergence of the rays, that the distance of the bodies should not be very considerable. To render an image visible, any vapour may be used ; for instance, the vapour of water, of m.ercury, of iodine, of chlorine, or bromine. As the rays which bodies emit thus spontaneously have a greater refrangibtlity than those yet known, they ordinarily begin the action on other substances with the greater intensity. There exists latent light as well as latent heat. When a liquor becomes vapour, light, which cor- responds to a certain extent of oscillation, becomes latent, and is set free again when the vapour is con- densed into liquid drops. It is for this reason that the condensation of vapours produces in some degree the same effects as light, and thus may be ex[)lained the operation of vapour. The condensation of vapours upon plates acts as light, whether the vapour in excess adheres simply as the vapour of water in most substances, or perma- nently as that of mercury; or even combines chemi- cally with the body, as, for instance, the vapour of iodine with silver. Such are the means by which Moser seeks to explain these most interesting phe- nomena ; and as a proof of the existence of latent light in mercury he has, during the past year, pub- lished the following experiment. Iodize a silver plate, and then heat it over a com- mon spirit-lamp for about a minute. The iodide of THERMOGRAPHY. 41 silver first becomes darker, and then milk white. This while substance is very sensitive to light, and is in this respect little inferior to any known. By ex- posure to light, and indeed by all of its colours, it is converted into a steel-gray. The plate must, there- fore, be protected from the direct light of the sun, and the experiment carried on in the back pa-rt of the room. When cold, it is placed behind a cut-out screen, which may be the distance of a line from the plate over mercury, which is heated to 60*^ R., and the temperature allowed to fall to 30° R. When the plate is now removed, it has become steel-gray wherever the vapour of mercury had access ; and in this manner the image of the aperture of the screen is obtained precisely as if ordinary light had fallen on to the plate. Although the condensed vapour of mercury is white, yet the action of its latent light preponderates in this case, and determines the colouring. Heat acts no part here, for it has not the power of rendering the white substance steel-gray ; nor can there be any question of chemical rays with this white substance, for all the rays of the spectrum con- vert it into steel-gray. 95. Paper Thermographs. — I have myself pro- duced on paper some impressions which I believe to be of a similar nature to those already described above. The manner in which these impressions were obtained may be thus briefly stated : — Evaporate to dryness chloride of gold, and dissolve the residue in distilled water. With this solution wash the paper, which must have been previously submitted to considerable pressure in contact with the picture to be copied for one or two days. The im- 4* 42 PHOTOGENIC MANIPULATION. pression may thus be supposed to be latent. When the paper, after being brushed with the solution, is dry, it must be passed through distilled water, and exposed to the sun's rays or to diffused daylight. The paper will soon darken, and ultimately assume a mulberry colour, leaving, however, a white impres- sion of the picture or marks with which it has been in contact. IV. — Electrical Impressions. 96. The analogy v/hich exists between many of the effects of heat and electricity induced continental philosophers to endeavour to ascertain whether im- pressions similar to those produced by light and heat might not be obtained by electricity. Dr. Reiss was the first, we believe, to publish* the successful results of such experiments, which were afterwards carried out to a much greater extent by M. Karsten.f The results of these experiments appearing to us to be of much importance, we propose to lay them before our readers. The first impressions obtained by M. Karsten were on glass in the following manner. A coin was placed on a piece of plate glass, which being supported by a plate of metal not insulated, and the sparks from the conductor of an electrifying machine were made to strike on the coin, thereby causing them to pass simul- taneously through the coin and the metallic plate. After one hundred turns of the machine, the coin was removed ; the glass plate appeared perfectly unaltered, but when breathed upon, a perfect impression of the coin in its most minute details became visible. Much * Repertoruim der Physick, vol. vi. p. 180. t Publislied in Poggendorff 's Anrmlen, No. 2, 1812. ELECTRICAL IMPRESSIONS. 43 of the success of this experiment appears to depend on the quality of the glass : the impressions appear as distinct on thick as on thin giass, with the excep- tion, that if coins are placed on both sides of the glass plates, they are then acted upon and affected in the same manner as the surface of the plate. If thin plates are used, several sheets may be placed one above the other, which then yield impressions, indeed, gradually less distinct, but still quite perceptible. It is immate- rial whether the ball of the conductor touches the coin, or whether the electric fluid passes in the shape of sparks ; on the other hand, it is very material to the distinctness and accuracy of the impressions, whether sparks are made to strike from the coin to the exterior metallic foil ; in cases where the electric fluid slowly escaped from the coin, the impressions were less distinct. Impressions of a like character were obtained on metallic plates, and they were much more distinct when a piece of oiled paper was placed between the coin and the plate, although impressions may likewise be obtained when the coin is in immediate contact with the metallic plate. The metallic quality of the coin appears to have some influence, the coins fabri- cated from the better conducting metals appearing to yield better impressions. Powerful shocks from a jar or battery do not appear to produce the same effect. M. Karsten has hitherto been unable to fix these impressions, for although the impressions on glass plates become visible during the action of fumes from quicksilver and iodine, they disappear immediately on being removed from the apparatus. 44 PHOTOGENIC MANIPULATION. M. Karsten makes the following reflections on these curious phenomena First. Is the impression produced by traces of the electric fluid remaining adherent to the glass plate T This question is negatived, for the reason that the impression stiil remains with great distinctness after all traces of electricity have disappeared, after the glass has been wiped with a handkerchief And again, these impressions are neither destroyed nor even weakened by passing a stream of the opposite electricity over them. And in the case of the metallic plates, partial adhesion of electricity is quite out of the question. Another question is, whether they are produced by an action which is similar to that which has pro- duced the impressions observed by Moser? or, whe- ther they may be ascribed to pepuliar electric action? The fact that this process is finished in a very short time, as compared with that required for the forma- tion of thermographs, does not admit of this inference being correct. A few turns are sufficient to produce outlines of the coins on the glass plate. 97. But an experiment recently published by Mr. Hunt, to whose name in the course of these pages we have had so often occasion to refer, appears to mili- tate against this last opinion of M. Karsten. It having been suggested to him that electricity might be en- gaged in the production of the spectral figures of thermography, he made the following experiment, with a view to ascertain the fact ; the result of which shows the probability of this element being involved in some way in these very complicated phenomena. " I arranged," says he, four electro-positive metals GALVANIC IMPRESSIONS. 45 — nickel, bismuth, cadmium, and silver, — and two electro-negative ones, arsenic and antimony, on a copper plate, and they v/efe allowM. to rest upon it for three hours. Being removed, the plate was sub- mitted to the vapour of mercury. The space covered by nickel was marked by being left free of vapour ; that on which the cadmiuA-Jay was still more de- cidedly marked in this way ; where the bismuth was placed the image was exceedingly faint, but still it was observable by a deficiency of vapour, and' the silver was more decidedly outlined by vapour, but none on the spot it covered. On the contrary, the space occupied by the antimony was covered in a most remarkable manner with vapour, presenting a perfectly white spot, which, in all positions, distin- guished it from the other parts of the plate, whilst the arsenic left no trace behind. 98. Galvanic Iiwpressioiis. — The observation that a weak insulator should intervene for the purpose of securing good impressions on metal (§ 96), led to the inference that the galvanic current might be employed for producing such impressions. Such impressions were obtained by M. Karsten, but not with any degree of distinctness. 99. It has been the object of the author, in this little work, to lead the experimentalist step by step to the proper understanding of the Photogenic art, — commencing with its simplest form, and thus pre- paring the way for its more complex manipulation. Of the ultimate applications of an art which is daily making new and gigantic strides, it is impossible to venture a prediction. In the language, however, of a high authority, it may be said that a process by 46 PHOTOGENIC MANIPULATION. which the most transient actions are rendered per- manent — by which facts write their own annals, in a language that can never become obsolete, forming documents which prove themselves- — must inter- weave itself, not only with science, but with history and legislature." Sdem quis dicere falaum audsat INDEX. Accelerating solutions, § 67. Actinism, Experiments in, § 88. Actino-Chemistry, § 88. Backgrounds for Photographs, § 81. Beard's patent for colouring Daguerreotypes, § 80. Berres, Dr., Etching Daguer- reotypes by, § 87. Brequet, M., Observations on Thermographs, § 93. Bromide of Iodine, § 70. Bromide Pans, § 66. Water, § 68. Chloride of Bromine, § 71. Gold, § 79. Iodine, § 69. Colouring Daguerreotypes, § 80, Conclusion, § 99. Constable's, Mr., Sliding Scale and Sand Clock, § 76 — § 83. Daguerreotype, The, thrown open by the French Govern- ment, § 59. Daguerreotype, Patented in England, § 60. Difference of, from other processes, § 61. Operations of, § 62. Daguerreotypes, Fixing of, §77. Gilding of § 79. Daguerreotype Plate, to clean, § 63. Exposure in Camera, § 75. Mercurializing, § 76. Drying Apparatus, § 78. Durability of PhotographSj § 85. Electrical Impressions, § 96. Energia, § 88. Etching Daguerreotypes, § 87. Figeau, M., his process for Etching Daguerreo- types, § 17o Gilding Daguerreotypes, § 79. Finishing Powder, § 64. Galvanic Impressions, § 98. Gilding Daguerreotypes, § 79. 48 INDEX. Grove, Professor, his process for Etching- Daguer- reotypes, § 87. Remarks on Thermogra- phy by, § 92. Hints for Amateurs, § 82. Hungarian Solution, § 73. Hunt, Mr. Robert, application of the Daguerreotype to paper, § 84, Discoverer of Thermo- graphy, § 91. On Electrical Impres- sions, § 97. Impressions, Electrical, § 96. Introduction, § 58. Iodine Box, § 65. Karsten, M,, experiments on Electrical Impressions, §96. Knight's Sensitive Solution, § 72. Latent Light, § 94. Mercury Box, § 76. Mercury, Latent Light of, § 94. Moser, Professor, Remarks of, on Thermography, § 94. Paper Daguerreotypes, § 84. Thermographs, § 95. Plate Holders, § 63. Photographs, Durability of, § 85. Sand Clock, Mr, Constable's, § 83. Sensitive Coating, Application of, § 65. Sliding Scale, Mr. Constable's, §76. Thermographs, § 91. Paper, § 95. Thermography, Discovery of, § 89. Professor Grove on, § 92. Professor Moser on, § 94. Tithinicity, § 88. Ulex, M., Experiments on Da- guerreotypes, § 86. • 0 # i