TECHNIQUE OF  See also:

• PHOTOGRAPHY (Gr. bias, light, and ypa w, to write)
• PHOTOGRAPHY, CELESTIAL

PHOTOGRAPHY See also:

• GELATIN, or GELATINE

Gelatin Emulsions . The following is an outline of two representative processes . All operations should be conducted in See also:

• LIGHT

light which can See also:

• ACT (Lat. actus, actum)

act but very slightly on the sensitive salts employed, and this is more necessary with this See also:

• PROCESS

process than with others on See also:

• ACCOUNT
• ACCOUNT (through O. Fr. acont, Late Lat. comptum, cornputare, to calculate)

account of the extreme ease with which the See also:

• EQUILIBRIUM (from the Lat. aequus, equal, and libra, a balance)

equilibrium of the molecules is upset in giving rise to the See also:

• MOLECULE (from mod. Lat. molecula, the diminutive of moles, a mass)

molecule which is developable . The light to See also:

• WORK

work with is gaslight or candlelight passing through a See also:

• SHEET

sheet of See also:

• CHANCE (through the O. Fr. cheance, from the Late Lat. cadentia, things happening, from cadere, to fall out, happen; cf. " case ")

Chance's stained red See also:

• GLASS
• GLASS (O.E. glees, cf. Ger. Glas, perhaps derived from an old Teutonic root gla-, a variant of glo-, having the general sense of shining, cf. " glare," " glow ")
• GLASS, STAINED

glass backed by See also:

• ORANGE
• ORANGE (Citrus Aurantium)
• ORANGE, HOUSE OF

orange See also:

• PAPER
• PAPER (Fr. papier, from Lat. papyrus)

paper . Stained red glass allows but few chemically effective rays to pass through it, whilst the orange paper diffuses the light . If daylight be employed, it is as well to have a See also:

• DOUBLE
• DOUBLE (from the Mid. Eng. duble, the form which gives the present pronunciation, through the Old Er. duble, from Lat. duplus, twice as much)

double thickness of orange paper . The following should be weighed out: i . See also:

• POTASSIUM [symbol K (from kalium), atomic weight 39.114 0=16)]

Potassium iodide 5 grs . 2 . Potassium bromide • 135 , . 3 . See also:

• NELSON
• NELSON, HORATIO NELSON, VISCOUNT (1758-1805)
• NELSON, ROBERT (s656-1715)

Nelson's No. i photographic gelatin .

30 „ 4 . See also:

• SILVER

Silver nitrate 175 ,, Autotype or other hard gelatin . . See also:

• IOO

ioo 5' Nelson's No . I gelatin . . . . See also:

• LOO (formerly called " Lanterloo," Fr. lanturlu, the refrain of a popular 17th-century song)

loo Nos . 3 and 5 are rapidly covered with See also:

• WATER

water or washed for a few seconds under the tap to get rid of any dust . No . 2 is dissolved in 11 oz. of water, and a little See also:

• TINCTURE (Fr. teinture, Lat. tinctura, tingere, to dye, stain)

tincture of See also:

• IODINE (symbol I, atomic weight '26.92)

iodine added till it assumes a light See also:

• SHERRY

sherry See also:

• COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour . No . I is dissolved in 6o minims of water . No .

4 is dissolved in z oz. of water, and No . 3 is allowed to swell up in i oz. of water, and is then dissolved by See also:

• HEAT (0. E. haktu, which like " hot," Old Eng. hat, is from the Teutonic type haita, hit, to be hot; cf. Ger. hitze, heiss; Dutch, hitte, heet, &c.)

heat . All the flasks containing these solutions are placed in water at 150° F. and carried into the " dark See also:

• ROOM

room,” as the orange-lighted chamber is ordinarily called; Nos . 3 and 4 are then mixed together in a See also:

• JAR

jar or See also:

• FLASK

flask, and No . 2 added drop by drop till See also:

• HALF

half its bulk is gone, when No. i is added to the See also:

• REMAINDER, REVERSION

remainder, and the double See also:

• SOLUTION (from Lat. solvere, to loosen, dissolve)

solution is dropped in as before . When all is added there ought to be formed an emulsion which is very ruddy when examined by gaslight, or orange by daylight . The flask containing the emulsion is next placed in boiling water, which is kept in a See also:

• STATE
• STATE, GREAT OFFICERS OF

state of ebullition for about three-quarters of an See also:

• HOUR

hour . It is then ready, when the contents of the flask have cooled down to about Too° F., for the addition of No . 5, which should in the See also:

• INTERVAL

interval be placed in 2 oz. of water to swell and finally be dissolved . The gelatin emulsion thus formed is placed in a cool See also:

• PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place to set, after which it is turned into a piece of coarse See also:

• CANVAS

canvas or See also:

• MOSQUITO (Span. mosquito, a gnat, diminutive of mosca, a fly)

mosquito netting made into a bag . By squeezing, threads of gelatin containing the sensitive See also:

• SALT (a common Teutonic word, cf. Dutch zout, Ger. Salz, Scand. salt; cognate with Gr. &Xs, Lat. sal)
• SALT, SIR TITUS, BART

salt can be made to fall into See also:

• COLD (in O. Eng. cald and ceald, a word coming ultimately from a root cognate with the Lat. gelu, gelidus, and common in the Teutonic languages, which usually have two distinct forms for the substantive and the adjective, cf. Ger. Kolte, kalt, Dutch koude

cold water; by this means the soluble salts are extracted . This is readily done in two or three See also:

• HOURS, CANONICAL

hours by frequently changing the water, or by allowing See also:

• RUNNING

running water to flow over the emulsion-threads .

The gelatin is next drained by straining canvas over a jar and turning out the threads on to it, after which it is placed in a flask, and warmed till it dissolves; half an See also:

• OUNCE

ounce of See also:

• ALCOHOL

alcohol being added . Finally it is filtered through See also:

• CHAMOIS

chamois See also:

• LEATHER (a word which appears in all Teutonic languages; cf. Ger. Leder, Dutch leer or leder, Swed. leder, and in such Celtic forms as Welsh llader)
• LEATHER, ARTIFICIAL

leather or swansdown See also:

• CALICO

calico . In this state it is ready for the plates . The other method of forming the emulsion is with See also:

• AMMONIA (NH3)

ammonia . The same quantities as before are weighed out, but the solutions of Nos . 2 and 3 are first mixed together and No . 4 is dissolved in 1 oz. of water, and strong ammonia of specific gravity •88o added to it till the See also:

• OXIDE

oxide first precipitated is just redissolved . This solution is then dropped into Nos . 2 and 3 as previously described, and finally No . T is added . In this See also:

• CASE
• CASE, JOHN (d. 1600)

case no boiling is required; but to secure rapidity it is as well that the emulsion should be kept an hour at a temperature of about 90° F., after which half the See also:

• TOTAL

total, quantity of No . 5 is added .

When set the emulsion is washed, drained, and redissolved as before; but in See also:

• ORDER
• ORDER (through Fr. ordre, for earlier ordene, from Lat. ordo, ordinis, rank, service, arrangement; the ultimate source is generally taken to be the root seen in Lat. oriri, rise, arise, begin; cf. " origin ")
• ORDER, HOLY

order to give tenacity to the gelatin the remainder of No . 5 is added before the addition of the alcohol, and before filtering . Coating the Plates.—Glass plates are best cleaned with nitric See also:

• ACID (from the Lat. root ac-, sharp; acere, to be sour)

acid, rinsed, and then treated with potash solution, rinsed again, and dried with a clean See also:

• CLOTH

cloth . They are then ready for receiving the emulsion, which, after being warmed to about 12o° F., is poured on them to See also:

• COVER (from the Fr. convert, from couvrir, to cover, Lat. cooperire)

cover well the See also:

• SURFACE

surface . This being done, the plates are placed on a level shelf and allowed to stay there till the gelatin is thoroughly set; they are then put in a drying See also:

• CUPBOARD

cupboard, through which a current of warm See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

air is made to pass . It should be remarked that the warmth is only necessary to enable the air to take up the moisture from the plates . They ought to dry in about twelve hours, and they are ready for use . Exposure.—With a See also:

• GOOD, JOHN MASON (1764-1827)

good emulsion and on a See also:

• BRIGHT, JOHN (1811-188g)
• BRIGHT, SIR CHARLES TILSTON

bright See also:

• DAY (O. Eng. dreg, Ger. Tag; according to the New English Dictionary, " in no way related to the Lat. dies")
• DAY, JOHN (1574-1640?)
• DAY, THOMAS (1748-1789)

day the exposure of a See also:

• PLATE

plate to a landscape, with a See also:

• LENS
• LENS (from Lat. lens, lentil, on account of the similarity of the form of a lens to that of a lentil seed)

lens whose See also:

• APERTURE (from Lat. aperire, to open)

aperture is one-sixteenth that of the See also:

• FOCAL

focal distance, should not be more than one-half to one-fifth of a second . This See also:

• TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
• TIME, MEASUREMENT OF
• TIME, STANDARD

time depends, of course, on the nature of the view; if there be foliage in the immediate foreground it will be longer . In the portrait-studio, under the same circumstances, an exposure with a portrait lens may be from half a second to four or five seconds . Development of the Plate.—To develop the See also:

• IMAGE (Lat. imago, perhaps from the same root as imitari, copy, imitate)

image either a ferrous oxalate solution or alkaline pyrogallic acid may be used . No chemical restrainer such as potassium bromide is necessary, since the gelatin itself acts as a See also:

• PHYSICAL

physical restrainer .

If the alkaline developer be used, the following may be taken as a good See also:

• STANDARD
• STANDARD, BATTLE OF THE

standard : (See also:

• PYROGALLOL, or PYROGALLIC ACID

Pyrogallol 50 grs . 1. j( Citric acid 10 „ Water . . t oz . 2 Potassium bromide to grs . Water I oz . 3 Ammonia, •88o I dr . Water 9 „ One dram of each of these is taken and the mixture made up to 2 OZ. with water . The plate is placed in a dish and the above poured over it without stoppage, whereupon the image gradually appears and, if the exposure has been properly timed, gains sufficient See also:

• DENSITY (Lat. densus, thick)

density for See also:

• PRINTING (from Lat. imprimere, O. Fr. empreindre)

printing purposes . It is fixed in a solution of hyposulphite of soda, as in the other processes already described, and then thoroughly washed for two or three hours to eliminate all the soluble salt . This See also:

• LONG, GEORGE (1800-1879)
• LONG, JOHN DAVIS (1838– )

long washing is necessary on account of the nature of the gelatin . Intensifying the Negative.—Sometimes it is necessary to intensify the negative, which can be done in a variety of ways with See also:

• MERCURY
• MERCURY (MERCU1uus)
• MERCURY (symbol Hg, atomic weight = 2oo)

mercury salts . An excellent See also:

• PLAN
• PLAN (from Lat. planes, flat)

plan, introduced by See also:

• CHAPMAN (from O. Eng. ceap, and Mid. Eng. ,heap, to barter, cf. " Cheapside " in London, and Ger. Kaufmann)
• CHAPMAN, GEORGE (? 1559–1634)

Chapman See also:

• JONES
• JONES, ALFRED GILPIN (1824-1906)
• JONES, EBENEZER (182o-186o)
• JONES, ERNEST CHARLES (1819-1869)
• JONES, HENRY (1831-1899)
• JONES, HENRY ARTHUR (1851- )
• JONES, INIGO (1573-1651)
• JONES, JOHN (c. 1800-1882)
• JONES, MICHAEL (d. 1649)
• JONES, OWEN (1741-1814)
• JONES, OWEN (1809-1874)
• JONES, RICHARD (179o-1855)
• JONES, SIR ALFRED LEWIS (1845-1909)
• JONES, SIR WILLIAM (1746-1794)
• JONES, THOMAS RUPERT (1819– )
• JONES, WILLIAM (1726-1800)

Jones, is to use a saturated solution of mercuric chloride in water .

After thorough washing the negative is treated with ferrous oxalate . This process can be repeated till sufficient density is attained . With most other methods with mercury the image is See also:

• APT

apt to become yellow and to fade; with this apparently it is not . Varnishing the Negative.—The negative is often protected by receiving first a film of See also:

• PLAIN (O. Fr. plain, from Lat. plenum)

plain See also:

• COLLODION (from the Gr. &M a' , glue)

collodion and then a coat of shellac or other photographic See also:

• VARNISH

varnish . This protects the gelatin from moisture and also from becoming stained with the silver nitrate owing to contact with the sensitive paper used in silver printing . Another varnish is a solution of celloidin in amyl acetate . This is an excellent See also:

• PROTECTION

protection against See also:

• DAMP

damp . Printing Processes . The first printing process may be said to be that of See also:

• FOX
• FOX, C
• FOX, CHARLES JAMES (1749-1806)
• FOX, EDWARD (c. 1496-1538)
• FOX, GEORGE (1624-1691)
• FOX, RICHARD (c. 1448-1528)
• FOX, ROBERT WERE (1789—1877)
• FOX, SIR STEPHEN (1627–1716)
• FOX, SIR WILLIAM (1812-1893)

Fox See also:

• TALBOT (FAMILY)
• TALBOT, MARY ANNE (1778-1808)
• TALBOT, WILLIAM HENRY FOX (1800–1877)

Talbot (see above), which has continued to be generally employed (with the addition of albumen to give a surface to the See also:

• PRINT

print—an addition first made, we believe, by Fox Talbot) . Paper for printing is prepared by mixing 150 parts of ammonium chloride with 240 parts of See also:

• SPIRITS

spirits of See also:

• WINE (Lat. vinum, Gr. oivos)

wine and 2000 parts of water, though the proportions may vary . These ingredients are dissolved, and the whites of fifteen fairly-sized eggs are added and the whole beaten up to a froth . In hot See also:

• WEATHER (O. Eng. weder; the word is common to Teutonic languages; cf. Du. weder, Dan. veir, Icel. ve8r, and Ger. Wetter and Gewitter, storm; the root is wa- to blow, from which is derived " wind ")

weather it is advisable to add a drop of carbolic acid to prevent decomposition .

The albumen is allowed two or three days to See also:

• SETTLE
• SETTLE, ELKANAH (1648–1724)

settle, when it is filtered through a sponge placed in a See also:

• FUNNEL (through an O. Fr. founil, found in Breton, from Lat. infundibulum, that through which anything is poured, from fundere, to pour)

funnel, or through two or three thicknesses of See also:

• FINE

fine See also:

• MUSLIN (through Fr. mousseline from It. mussolino, diminutive of Mussolo, i.e. the town Mosul in Kurdistan)

muslin, and transferred to a See also:

• FLAT (a modification of O. Eng. flet, an obsolete word of Teutonic origin, meaning the ground beneath the feet)

flat dish . The paper is cut of convenient See also:

• SIZE

size and allowed to See also:

• FLOAT (in O. Eng. floc and flota, in the verbal form f eotan; the Teutonic root is flut-, another form of flu-, seen in " flow," cf. " fleet "; the root is seen in Gr. a-M e, to sail, Lat. pluere, to rain; the Lat, fluere and fluctus, wave, is not connect

float on the solution for about a See also:

• MINUTE
• MINUTE (Lat. minutes, small; minuere, to make less)

minute, when it is taken off and dried in a warm room . For dead prints, on which colouring is to take place, plain salted paper is useful . It can be made of the following proportions—go parts of ammonium chloride, too parts of See also:

• SODIUM [symbol Na, from Lat. natrium; atomic weight 23.00 (0=16)]

sodium citrate, to parts of gelatin, 5000 parts of distilled water . The gelatin is first dissolved in hot water and the remaining components are added . It is next filtered, and the paper allowed to float on it for three minutes, then withdrawn and dried . Sensitizing See also:

• BATH
• BATH, THOMAS THYNNE
• BATH, WILLIAM

Bath.—To sensitize the paper it is floated on a 10% solution of silver nitrate for three minutes . It is then hung up and allowed to dry, after which it is ready for use . To print the image the paper is placed in a printing See also:

• FRAME

frame over a negative and exposed to light . It is allowed to print till such time as the image appears rather darker than it should finally appear . Toning and Fixing the Print.—The next operation is to See also:

• TONE, THEOBALD WOLFE (1763-1798)

tone and See also:

• FIX, THEODORE (180o-1846)

fix the print . In the earlier days this was accomplished by means of a bath of sel d'or—a mixture of hyposulphite of soda and See also:

• GOLD
• GOLD [symbol Au, atomic weight 195.7(H = 1),197.2(0 =16)]

gold chloride .

This gilded the darkened parts of the print which light had reduced to the semi-metallic state: and on the removal of the chloride by means of hyposulphite an image composed of metallic silver, an organic salt of silver and gold was See also:

• LEFT

left behind . There was a suspicion, however, that See also:

• PART

part of the coloration was due to a See also:

• COMBINATION (Lat. combinare, to combine)

combination of See also:

• SULPHUR

sulphur with the silver, not that pure silver sulphide is in any degree fugitive, but the sulphuretted organic salt of silver seems to be liable to See also:

• CHANGE (derived through the Fr. from the Late Lat. cambium, cambiare, to barter; the ultimate derivation is probably from the root which appears in the Gr. «a urmu', to bend)

change . This gave place to a method of alkaline toning, or rather, we should say, of neutral toning, by employing gold chloride with a salt, such as the carbonate or acetate of soda, chloride of See also:

• LIME
• LIME (O. Eng. lim, Lat. limes, mud, from linere, to smear)

lime, See also:

• BORAX (sodium pyroborate or sodium biborate)

borax, &c . By this means there was no danger of sulphurization during the toning, to which the method by sel d'or was prone owing to the decomposition of the hyposulphite . The substances which can be employed in toning seem to be those in which an alkaline See also:

• BASE

base is combined with a weak acid, the latter being readily displaced by a stronger acid, such as nitric acid, which must exist in the paper after printing . This See also:

• BRANCH (from the Fr. branche, late Lat. branca, an animal's paw)

branch of photography owes much to the Rev . T . F . Hardwich, he having carried on extensive researches in connexion with it during 1854 and subsequent years . A . Davanne and A . See also:

• GIRARD, JEAN BAPTISTE [known as " Le Pere Girard " or" Le Pere Gregoire "] (1765-185o)
• GIRARD, PHILIPPE HENRI DE (1775-1845)
• GIRARD, STEPHEN (1750-1831)

Girard, a little later, also investigated the See also:

• MATTER

matter with fruitful results .

The following may be taken as two typical toning-See also:

• BATHS

baths:—Gold chloride 1 part . Sodium carbonate to parts . Water 5000 „ (a) Borax loo „ } Water 4000 (~) S Gold chloride 1 part . l j Water 4000 parts In the latter (a) and (0) are mixed in equal parts immediately before use . Each of these is better used only once . A third bath is: Gold chloride 2 parts . Chloride of lime 2 „ See also:

• CHALK

Chalk 40 „ Water 8000 , These are mixed together, the water being warmed . When cool the solution is ready for use . In toning prints there is a distinct difference in the modus operandi according to the toning-bath employed . Thus in the first two baths the print must be thoroughly washed in water to remove all See also:

• FREE

free silver nitrate, that salt forming no part in the chemical reactions . On the other See also:

• HAND
• HAND (a word common to Teutonic languages; cf. Ger. Hand, Goth. handus)
• HAND, FERDINAND GOTTHELF (1786-185r)

hand, where free See also:

• CHLORINE (symbol Cl, atomic weight 35`46 (0=16)

chlorine is used, the presence of free silver nitrate or some active chlorine absorbent is a See also:

• NECESSITY (Lat. necessitas)

necessity . In 1872 Abney showed that with such a toning-bath free. silver nitrate might be eliminated, and if the print were immersed in a solution of a salt such as See also:

• LEAD
• LEAD (pronounced iced)

lead nitrate the toning See also:

• ACTION

action proceeded rapidly and without causing any fading of the image whilst toning, which was not the case when the free silver nitrate was totally removed and no other chlorine absorbent substituted .

This was an important See also:

• FACTOR (from Lat. facere, to make or do)

factor, and one which had been overlooked . In the third bath the free silver nitrate should only be partially removed by washing . The print, having been partially washed or thoroughly washed, as the case may be, is immersed in the toning-bath till the image attains a See also:

• PURPLE

purple or bluish tone, after which it is ready for fixing . The solution used for this purpose is a 20% solution of hyposulphite of soda, to which it is best to add a See also:

• DEW

dew drops of ammonia in order to render it alkaline . About ten minutes suffice to effect the See also:

• CONVERSION (Lat. conversio, from convertere, to turn or ,change)

conversion of the chloride into hyposulphite of silver, which is soluble in hyposulphite of soda and can be removed by washing . The organic salts of silver seem, however, to See also:

• FORM (Lat. forma)

form a different salt, which is partially insoluble, but which the ammonia See also:

• HELPS, SIR ARTHUR (1813-1875)

helps to remove . If it is not removed there is a sulphur See also:

• COMPOUND
• COMPOUND (from Lat. componere, to combine or put together)

compound left behind, according to J . Spitler, which by time and exposure becomes yellow . The use of potassium See also:

• CYANIDE

cyanide for fixing prints is to be avoided, as this reagent attacks the organic coloured oxide which, if removed, would render the print a See also:

• GHOST (a word common to the W. Teutonic languages; O.E. vest, Dutch, 'geest, Ger. Geist)

ghost . The washing of silver prints should be very See also:

• COMPLETE

complete, since it is said that the least trace of hyposulphite left behind renders the fading of the image a See also:

• MERE
• MERE, ADALBERT (1838-1909)

mere matter of time . The stability of a print has been supposed to be increased by immersing it, after washing, in a solution of See also:

• ALUM

alum . The alum, like any .acid See also:

• BODY

body, decomposes the hyposulphite into sulphur and sulphurous acid .

If this be the case, it seems probable that the destruction of the hyposulphite by time is not the occasion of fading, but that its hygroscopic See also:

• CHARACTER (Gr. xapareri7p, from xap&crew, to scratch)

character is . This, however, is a See also:

• MOOT

moot point . It is usual to See also:

• WASH, THE

wash the prints some hours in running water . We have found that half a dozen changes of water, and between successive changes the application of a sponge to the back of each print separately, are equally or more efficacious . On drying the print assumes a darker tone than it has after leaving the fixing bath . Different tones can thus be given to a print by different toning-baths; and the gold itself may be deposited in a ruddy form or in a See also:

• BLUE (common in different forms to most European languages)

blue form . The former molecular See also:

• CONDITION (Lat. condicio, from condicere, to agree upon, arrange; not connected with conditio, from condere, conditum, to put together)

condition gives the red and See also:

• SEPIA (Gr. a iria, cuttlefish)

sepia tones, and the latter the blue and See also:

• BLACK
• BLACK, ADAM (1784-1874)
• BLACK, JEREMIAH SULLIVAN (1810–1883)
• BLACK, WILLIAM (1841-1898)

black tones . The degree of minute subdivision of the gold may be conceived when it is stated that, on a couple of sheets of albuminized paper fully printed, the gold necessary to give a decided tone does not exceed half a See also:

• GRAIN (derived through the French from Lat. granum, seed, from an Aryan root meaning " to wear down," which also appears in the common Teutonic word " corn ")

grain . Collodio-chloride Silver Printing Process.—In the See also:

• HISTORY

history of the emulsion processes we stated that Gaudin attempted to use silver chloride suspended in collodion, but it was not till the See also:

• YEAR

year 1864 that any See also:

• PRACTICAL

practical use was made of the See also:

• SUGGESTION

suggestion so far as silver printing is concerned . In the autumn of that year See also:

• GEORGE
• GEORGE, 8TH MARQUESS OF TWEEDDALE (1787-1876)
• GEORGE, HENRY (1839—1897)
• GEORGE, LAKE
• GEORGE, SAINT (d. 303)

George See also:

• WHARTON (FAMILY)
• WHARTON, FRANCIS (1820–1889)
• WHARTON, HENRY (1664–1695)

Wharton See also:

• SIMPSON, MATTHEW (1811-1884)
• SIMPSON, SIR JAMES YOUNG (1811-1870)
• SIMPSON, THOMAS (1710-1761)

Simpson worked out a method which has been more or less successfully employed . The See also:

• FORMULA
• FORMULA (Lat. diminutive of forma, shape, pattern, &c., especially used of rules of judicial procedure)

formula appended is Simpson's: Silver nitrate 60 parts . I Distilled water 6o „ See also:

• STRONTIUM [Symbol Sr, atomic weight 87.62 (0=16)]

Strontium chloride 64 Alcohol woo Citric acid 64 „ Alcohol t000 To every moo parts of plain collodion 30 parts of No. i, previously mixed with 6o parts of alcohol, are added; 6o parts of No .

2 are next mixed with the collodion, and finally 30 parts of No . 3 . This forms an emulsion of silver chloride and also contains citric acid and silver nitrate . The defect of this emulsion is that it contains a large proportion of soluble salts, which are apt to crystallize out on drying, more particularly if it be applied to glass plates . The addition of the citric acid and the excess of silver nitrate is the See also:

• KEY
• KEY (in O. Eng. tang; the ultimate origin of the word is unknown; it appears only in Old Frisian kei of other Teutonic languages; until the end of the 17th century the pronunciation was kay, as in other words in O. Eng. ending in aeg; cf. daeg, day; clang
• KEY (the phraseograms being indicated by hyphens)
• KEY, SIR ASTLEY COOPER (1821-1888)
• KEY, THOMAS HEWITT (1799-1875)

key to the whole process; for, unless some body were See also:

• PRESENT

present which on exposure to light was capable of forming a highly-coloured organic oxide of silver, no vigour would be obtained in printing . If pure chloride be used, though an apparently strong image would be obtained, yet on fixing only a feeble trace of it would be left, and the print would be worthless . The collodio-chloride emulsion may be applied to glass, or to paper, and the printing carried on in the usual manner . The toning takes place by means of the chloride of lime or by ammonium sulphocyanide and gold, which is practically a return to the sel d'or bath . The organic salt formed in this See also:

• PROCEDURE (Fr. procedure, from Lat. procedere, to go for-ward)

procedure does not seem so prone to be decomposed by keeping as does that formed by albumen, and the washing can be more completely carried out . There are in the See also:

• MARKET (Lat. mercatus, trade or place of trade)

market several papers which are collodio-chloride . Gelatino-citro-chloride Emulsion.—A modified emulsion printing process was introduced by Abney in 1881, which consisted in See also:

• SUS

sus-pending silver chloride and silver citrate in gelatin, there being no excess of silver present . The formula of producing it is as follows: Sodium chloride 40 parts .

1 . Potassium citrate 40 Water 500 2 Silver nitrate 150 Water 500 Gelatin 300 Water 1700 Nos . 2 and 3 are mixed together whilst warm, and No. t is then gently added, the gelatin solution being kept in brisk agitation . This produces the emulsion of citrate and chloride of silver . The gelatin containing the suspended salts is heated for five minutes at boiling point, when it is allowed to cool and subsequently slightly washed, as in the gelatino-bromide emulsion . It is then ready for application to paper or glass . The prints are of a beautiful colour, and seem to be fairly permanent . They may be readily toned by the borax or by the chloride of lime toning-bath, and are fixed with the hyposulphite solution of the strength before given . Most, if not all, of the gelatin papers now extant are made somewhat after this manner . Printing with Salts of See also:

• URANIUM [symbol U, atomic weight 238.5 (0=16)]

Uranium.—The sensitiveness of the salts of uranium to light seems to have been discovered by See also:

• NIEPCE, JOSEPH NICEPHORE (1765-1833)

Niepce, and was subsequently applied to photography by J . E . See also:

• BURNETT, FRANCES ELIZA HODGSON (1849– )

Burnett in See also:

• ENGLAND
• ENGLAND, THE CHURCH OF

England .

One of the See also:

• ORIGINAL

original formulae consisted of 20 parts of uranic nitrate with 60o parts of water . Paper, which is better if slightly sized previously with gelatin, is floated on this solution . When dry it is exposed beneath a negative, and a very faint image is produced; but it can be See also:

• DEVELOPED

developed into a strong one by 6 to to % solution of silver nitrate to which a trace of acetic acid has been added, or by a 2 % solution of gold chloride . In both these cases the silver and gold are deposited in the metallic state . Another developer is a 2% solution of potassium ferrocyanide to which a trace of nitric acid has been added, sufficient to give a red coloration . The development takes place most readily by letting the paper float on these solutions . Self-toning Papers.—There are several self-toning papers based on the chloride emulsion process . These contain the necessary amount of gold to tone the print . The print is produced in the See also:

• ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary way and then immersed in salt and water or in some cases potassium sulphocyanide . The print is finished by immersing in weak hyposulphite of soda . Printing with Chromates: See also:

• CARBON (symbol C, atomic weight 12)

Carbon Prints.—The first mention of the use of potassium bichromate for printing purposes seems to have been made by Mungo Ponton in May 1839, when he stated that paper, if saturated with this salt and dried, and then exposed to the See also:

• SUN
• SUN (0. Eng. sonne, Ger. sonne. Fr. soleil, Lat. sol, Gr. ijXior, from which comes helio- in various English compounds)

sun's rays through a See also:

• DRAWING

drawing, would produce a yellow picture on an orange ground, nothing more being required to fix it thanwashing it in water, when a See also:

• WHITE
• WHITE, ANDREW DICKSON (1832– )
• WHITE, GILBERT (1720–1793)
• WHITE, HENRY KIRKE (1785-1806)
• WHITE, HUGH LAWSON (1773-1840)
• WHITE, JOSEPH BLANCO (1775-1841)
• WHITE, RICHARD GRANT (1822-1885)
• WHITE, ROBERT (1645-1704)
• WHITE, SIR GEORGE STUART (1835– )
• WHITE, SIR THOMAS (1492-1567)
• WHITE, SIR WILLIAM ARTHUR (1824--1891)
• WHITE, SIR WILLIAM HENRY (1845– )
• WHITE, THOMAS (1628-1698)
• WHITE, THOMAS (c. 1550-1624)

white picture on an orange ground was obtained . In 184o Edmond See also:

• BECQUEREL

Becquerel announced that paper sized with iodide of See also:

• STARCH

starch and soaked in potassium bichromate was, on drying, more sensitive than unsized paper .

See also:

• JOSEPH
• JOSEPH, COMTE DE (1785-1870)
• JOSEPH, FATHER (FRANCOIS LECLERC DU TREMBLAY) (1577-1638)

Joseph See also:

• DIXON
• DIXON, GEORGE (1755 ?–1800)
• DIXON, HENRY HALL (1822-1870)
• DIXON, RICHARD WATSON (1833-1900)
• DIXON, WILLIAM HEPWORTH (1821-1879)

Dixon of See also:

• MASSACHUSETTS (an Indian name, originally applied to a tribe of Indians)

Massachusetts, in the following year, produced copies of See also:

• BANK

bank-notes by using See also:

• GUM (Fr. gomme, Lat. gommi, Gr. Kµµ1, possibly a Coptic word; distinguish " gum," the fleshy covering of the base of a tooth, in O. Eng. gbma, palate, cf. Ger. Gaumen, roof of the mouth; the ultimate origin is probably the root gha, to open wide, seen in

gum arabic with potassium bichromate spread upon a lithographic See also:

• STONE
• STONE (0. Eng. shin; the word is common to Teutonic languages, cf. Ger. Stein, Du. steen, Dan. and Swed. sten; the root is also seen in Gr. aria, pebble)
• STONE, CHARLES POMEROY (1824-1887)
• STONE, EDWARD JAMES (1831-1897)
• STONE, FRANK (1800-1859)
• STONE, GEORGE (1708—1764)
• STONE, LUCY [BLACKWELL] (1818-1893)
• STONE, MARCUS (184o— )
• STONE, NICHOLAS (1586-1647)

stone, and, after exposure of the sensitive surface through a bank-See also:

• NOTE
• NOTE (Lat. nota, mark, sign, from noscere, to know)

note, by washing away the unaltered gum and inking the stone as in ordinary See also:

• LITHOGRAPHY (Gr. MOOS, a stone, and ypakecv, to write)

lithography . The same process, with slight modifications, has been used by Simonau and Toovey of See also:

• BRUSSELS (Fr. Bruxelles, Flem. Brussel)

Brussels, and produces excellent results . Dixon's method, however, was published in the Scientific See also:

• AMERICAN

American for 1854, and consequently, as regards priority, it ranks after Fox Talbot's photo-See also:

• ENGRAVING

engraving process (see below), published in 1852 . On the 13th of See also:

• DECEMBER (Lat. decent, ten)

December 1855 See also:

• ALPHONSE, COUNT OF TOULOUSE AND OF POITIERS (I220-1271)

Alphonse Poitevin took out a patent in England, in which he vaguely described a method of taking a See also:

• DIRECT

direct carbon-print by rendering gelatin insoluble through the action of light on potassium bichromate . This See also:

• IDEA (Gr. Ibia, connected with i&eiv, to see; cf. Lat. species from specere, to look at)

idea was taken up by See also:

• JOHN
• JOHN (1167–1216)
• JOHN (1290-c. 1320)
• JOHN (1296-1346)
• JOHN (1371–1419)
• JOHN (1468-1532)
• JOHN (1801-1873)
• JOHN (Heb. llni')
• JOHN (ZAPOLYA) (1487-1540)
• JOHN, 4TH MARQUESS OF TWEEDDALE (c. 1695-1762)
• JOHN, DON (1545-1578)
• JOHN, DON (1629–1679)
• JOHN, GOSPEL OF ST
• JOHN, or HAYS (1513–1571)
• JOHN, THE APOSTLE
• JOHN, THE EPISTLES OF

John Pouncey of See also:

• DORCHESTER
• DORCHESTER, DUDLEY CARLETON, VISCOUNT (1573-1632)
• DORCHESTER, GUY CARLETON

Dorchester, who perhaps was the first to produce veritable carbon-prints, notwithstanding that Testud de See also:

• BEAUREGARD, MARQUIS DE (c. 1772–?)
• BEAUREGARD, PIERRE GUSTAVE TOUTANT (1818-1893)

Beauregard took out a somewhat similar patent to Poitevin's at the end of 1857 . Pouncey published his process on the 1st of See also:

• JANUARY

January 1859; but, as described by him, it was by no means in a perfect state, half-tones being wanting . The cause of this was first pointed out by See also:

• ABBE (Serbo-Croatian Rai))

Abbe Laborde in 1858, whilst describing a kindred process in a note to the See also:

• FRENCH
• FRENCH, DANIEL CHESTER (1850– )
• FRENCH, NICHOLAS (1604-1678)

French Photographic Society . He says, " In the sensitive film, however thin it may be, two distinct surfaces must be recognized—an See also:

• OUTER

outer, and an inner which is in contact with the paper . The action of light commences on the outer surface; in the washing, therefore, the half-tones lose their hold on the paper and are washed away.” J . C . Burnett in 1858 was the first to endeavour to get rid of this defect in carbon printing . In a paper to the Photographic Society of See also:

• LONDON

London he says, " There are two essential requisites .

(2) that in printing the paper should have its unprepared See also:

• SIDE
• SIDE (mod. Eski Adalia)

side (and not its prepared side, as in ordinary printing) placed in contact with the negative in the pressure-frame, as it is only by printing in this way that we can expect to be able after-wards to remove by washing the unacted-upon portions of the mixture . In a See also:

• POSITIVE (or PORTABLE) ORGAN

positive of this sort printed from the front or pre-pared side the attainment of half-tones by washing away more or less See also:

• DEPTH

depth of the mixture, according to the depth to which it has been hardened, is prevented by the insoluble parts being on the surface and in consequence protecting the soluble part from the action of the water used in washing; so that either nothing is removed, or by steeping very long till the inner soluble part is sufficiently softened the whole depth comes bodily away, leaving the paper white.” This method of exposing through the back of the paper was crude and unsatisfactory, and in 186o Fargier patented a process in which, after exposure to light of the gelatin film which contained pigment, the surface was coated with collodion, and the print placed in warm water, where it separated from the paper support and could be transferred to glass . Poitevin success-fully opposed this patent, for he had used this means of detaching the films in his See also:

• POWDER (through O. Fr. puldre, modern poudre, from Lat. pulvis, pulveris, dust)

powder-carbon process, in which ferric chloride and tartaric acid were used . Fargier at any See also:

• RATE

rate gave an impetus to carbon-printing, and J . W . See also:

• SWAN (A. S. swan and swan, Icel. svanr, Du. zwaart, Ger. Schwan)
• SWAN, J
• SWAN, JOHN MACALLAN (1847-1910)
• SWAN, SIR JOSEPH WILSON (1828– )

Swan took up the matter, and in 1864 secured a patent . One of the See also:

• GREAT

great features in Swan's innovations was the See also:

• PRODUCTION (Lat. productionem, from producere, to pro-duce)

production of what is now known as " carbon-See also:

• TISSUE (Fr. tissu, tissue, participle of tisser, Lat. texere, to weave)

tissue," made by coating paper with a mixture of gelatin, See also:

• SUGAR

sugar and colouring matter, and rendered sensitive to light by means of potassium or ammonium bichromate . After exposure to light Swan placed the printed carbon-tissue on an See also:

• INDIA
• INDIA, FRENCH

india-See also:

• RUBBER, INDIARUBBER

rubber surface, to which it was made to adhere by pressure . The print was immersed in hot water, the paper backing stripped off, and the soluble gelatin containing colouring matter washed away . The picture could then be retransferred to its final support of paper . In 1869 J . R .

See also:

• JOHNSON, ANDREW
• JOHNSON, ANDREW (1808–1875)
• JOHNSON, BENJAMIN (c. 1665-1742)
• JOHNSON, EASTMAN (1824–1906)
• JOHNSON, REVERDY (1796–1876)
• JOHNSON, RICHARD (1573–1659 ?)
• JOHNSON, RICHARD MENTOR (1781–1850)
• JOHNSON, SAMUEL (1709-1784)
• JOHNSON, SIR THOMAS (1664-1729)
• JOHNSON, SIR WILLIAM (1715–1774)
• JOHNSON, THOMAS

Johnson of London took out a patent in which he claimed that carbon-tissue which had been soaked in water for a See also:

• SHORT, FRANCIS JOB (1857– )

short See also:

• PERIOD
• PERIOD (Gr. irepioSos, a going or way round, circuit, aepi, round, and &Sis, way, road)

period, by its tendency to swell further, would adhere to any waterproof surface such as glass, See also:

• METAL
• METAL (through Fr. from Lat. metallum, mine, quarry, adapted from Gr. µATaXAov, in the same sense, probably connected with ,ueraAAdv, to search after, explore, µeTa, after, aAAos, other)

metal, waxed paper, &c., without any adhesive material being applied . This was a most important improvement . Johnson also applied See also:

• SOAP

soap to the gelatin to prevent its excessive brittleness on drying, and made its final support of gelatinized paper, rendered insoluble by chrome alum . In 1874 J . R . See also:

• SAWYER, SIR ROBERT (1633-1692)

Sawyer patented a flexible support for developing on; this was a sized paper coated with gelatin and treated with an ammoniacal solution of shellac in borax, on which See also:

• WAX

wax or See also:

• RESIN (through O.Fr. resine, modern reline, from Lat. resina, prcbably Latinized from Greek Pirivrt, resin)

resin was rubbed . The See also:

• ADVANTAGE

advantage of this flexible support is that the dark parts of the picture have no tendency to See also:

• CONTRACT
• CONTRACT (Lat. contract us, from contrahere, to draw together, to bind)

contract from the lighter parts, which they were apt to do when a metal plate was used, as was the case in Johnson's original process . With this patent, and See also:

• MINOR
• MINOR (Lat. for smaller, lesser)
• MINOR, ROBERT CRANNELL (1839-1904)

minor improvements made since, carbon-printing has arrived at its present state of perfection . According to P . E . Liesegang, the carbon-tissue when prepared on a large See also:

• SCALE
• SCALE (1) A

scale consists of from 120 to 150 grains of gelatin (a soft See also:

• KIND (O. E. ge-cynde, from the same root as is seen in " kin," supra)

kind), 15 grains of soap, 21 grains of sugar and from 4 to 8 grains of dry colouring matter . The last-named may be of various kinds, from See also:

• LAMP (from Gr. Xag ras, a torch, Xaµaav, to shine)

lamp-black pigment to soluble See also:

• COLOURS, MILITARY

colours such as See also:

• ALIZARIN, or I

alizarin .

The gelatin, sugar and soap are put in water and allowed to stand for an hour, and then melted, the liquid afterwards receiving the 3 . colours, which have been ground on a slab . The mixture is filtered I the whole became coagulated rendered these unmanageable . It through fine muslin . In making the tissue in large quantities the at last occurred to him that if the hardening action of light were two ends of a piece of See also:

• ROLL (O. Fr. rolle, roulle, mod. role, Lat. rotulus, dim. of rota, wheel)
• ROLL, ALFRED PHILIPPE (1846– )

roll-paper are pasted together and the paper utilized by exposing the surface next the plate to light after or hung on two rollers; one of See also:

• WOOD, ANTHONY A2 (1632-1695)
• WOOD, JOHN GEORGE (1827—1889)
• WOOD, MRS HENRY [ELLEN] (1814—1887)
• WOOD, SEARLES VALENTINE (1798—188o)

wood about 5 in. in See also:

• DIAMETER (from the Cr. &a, through, µErpov, measure)

diameter is fixed before exposingg the front surface to the film and the image, the near the See also:

• TOP (cf. Dan. top, Ger. Topf, also meaning pot)

top of the room and the other over a trough containing necessary hardness might be given to the gelatin without adding the gelatin solution, the paper being brought into contact with any chemical hardeners to it . In Tessie de Motay's process the the surface of the gelatin by being made to revolve on the rollers. hardening was almost absent, and the plates were consequently not The thickness of the coating is proportional to the rate at which durable . It is evident that to effect this one of two things had to the paper is See also:

• DRAWN

drawn over the gelatin: the slower the See also:

• MOVEMENT

movement, the be done: either the metallic plate used by Tessie de Motay must thicker the coating . The paper is taken off the rollers, cut through, be abandoned, or else the film must be stripped off the plate and and hung up to dry on wooden laths . If it he required to make exposed in that manner . See also:

• ALBERT
• ALBERT (1490'1545)
• ALBERT (149o-1568)
• ALBERT (1522–1557)
• ALBERT (FRANCIS CHARLES AUGUSTUS ALBERT EMMANUEL) (1819—1861)
• ALBERT (FRIEDRICH RUDOLF ALBRECHT)
• ALBERT, FREDERICK AUGUSTUS
• ALBERT, MADAME (c. 2805—2846)

Albert adopted the transparent plate, the tissue sensitive at once, 12o grains of potassium bichromate and his success was assured, since instead of less than a See also:

• HUNDRED

hundred should be mixed with the ingredients in the above formula . The impressions being pulled from one plate he was able to take over a carbon-tissue when prepared should be floated on a sensitizing thousand . This occurred about 1867, but the formula was not bath consisting of one part of potassium bichromate in 40 parts published for two or three years afterwards, when it was divulged of water .

This is effected by turning up about t in. from the by See also:

• OHM, GEORG SIMON (1787-1854)

Ohm and Grossman; one of whom had been employed by Albert end of the sheet of tissue (cut to the proper size), making a roll of See also:

• MUNICH (Ger. Munchen)

Munich, and had endeavoured to introduce a process which of it, and letting it unroll along the surface of the sensitizing solu- resembled Albert's earlier efforts . The name of " Lichtdruck " was tion, where it is allowed to remain till the gelatin film feels soft. given about this time to these surface-printing processes, and Albert It is then taken off and hung up to dry in a dark room through may be considered, if not the inventor, at all events the perfecter of which a current of dry warm air is passing . Tissue dried quickly, the method . Another modification of " Lichtdruck " was patented though not so sensitive, is more manageable to work than If more in England by Ernest See also:

• EDWARDS, AMELIA ANN BLANDFORD (1831-1892)
• EDWARDS, BELA BATES (18o2-1852)
• EDWARDS, BRYAN (1743–1800)
• EDWARDS, GEORGE (1693–1773)
• EDWARDS, HENRY THOMAS (1837–1884)
• EDWARDS, JONATHAN (1703—1758)
• EDWARDS, LEWIS (1806–1887 )
• EDWARDS, RICHARD (c. 1523–1566)
• EDWARDS, T
• EDWARDS, THOMAS CHARLES (1837–1900)

Edwards under the name of " heliotype." slowly dried . As the tissue is coloured, it is not possible to ascertain See also:

• WOODBURY
• WOODBURY, CHARLES HERBERT (1864— )
• WOODBURY, LEVI (1789—1851)

Woodbury Type.—This process was invented by W . Woodbury by inspection whether the printing operation is sufficiently carried about the year 1864, though we believe that' J . W . Swan had been out, and in order to ascertain this it is usual to place a piece of working independently in the same direction about the same time. ordinary silvered paper in an See also:

• ACTINOMETER (Gr. locals, ray, ,arpov, measure)

actinometer, or photometer, alongside In See also:

• OCTOBER

October 1864 a description of the invention was given in the the carbon-tissue to ascertain the amount of light that has acted Photographic See also:

• NEWS

News . Marc See also:

• ANTOINE, ANDRE (1858- )

Antoine A . Gaudin claimed the principle on it . There are several devices for ascertaining this amount, the of the process, insisting that it was old, and basing his pretensions simplest being an arrangement of a varying number of thicknesses on the fact that he had printed with translucent See also:

• INK (from Late Lat. encaustum, Gr. gysavorov, the purple ink used by Greek and Roman emperors, from iyKaiew, to burn in)

ink from See also:

• INTAGLIO (an Ital. word, from intagliare, to incise, cut into)

intaglio of gold-beater's skin . The value of 1, 2, 3, &c., thicknesses of the blocks engraved by hand; but at the same time he remarked that skin as a See also:

• SCREEN (usually, but very doubtfully, connected with Lat. scrinium, a box for holding books, from scribere, to write; a connexion with Ger. Schranke, barrier, has been suggested)

screen to the light is ascertained by experiment .

Sup- the application of the principle might lead to important results. posing it is judged that a sheet of tissue under some one negative It was just these results which Woodbury obtained, and for which ought to be exposed to light corresponding to a given number of he was entitled to the fullest See also:

• CREDIT (Lat. credere, to believe)

credit . Woodbury subsequently thicknesses, chloride of silver paper is placed alongside the negative introduced certain modifications, the outcome being what is known beneath the actinometer and allowed to remain there until it takes as the " stannotype process," of which in 188o he read a description a visible tint beneath a number of thicknesses See also:

• EQUIVALENT

equivalent to the before the French Photographic Society (see PROCESS) . strength of the negative . After the tissue is removed from the Photo-lithography.—Reference has been made to the effect of printing-frame--supposing a double See also:

• TRANSFER (from Lat. transferre, to bear across, carry over)

transfer is to be made—it is light on gelatin impregnated with potassium bichromate, whereby placed in a dish of cold water, See also:

• FACE (from Lat. fades, derived either from facere, to make, or from a root fa-, meaning " appear "; cf. Gr. cbatvstv)

face downwards, along with a piece the gelatin becomes insoluble, and also incapable of absorbing water of Sawyer's flexible support . When the edges of the tissue begin where the action of the light has had full See also:

• PLAY

play . It is this last to curl up, its surface and that of the flexible support are brought phenomenon which occupies such an important place in photo-together and placed flat . The water is pressed out with an india- lithography . In the See also:

• SPRING (from " to spring," " to leap or jump up," " burst out," O. Eng., springau, a common Teut. word, cf. Ger. springer, possibly allied to Gr. QnrFpxecOac, to move rapidly)

spring of 1859 E . J . See also:

• ASSER, or ASSERIUS MENEVENSIS (d. c. 910)

Asser of See also:

• AMSTERDAM
• AMSTERDAM (NEw AMSTERDAM)

Amsterdam rubber squeezer or " squeegee " and the two surfaces adhere . About produced photographs on a paper basis in printer's ink . Being a couple of minutes later they are placed in warm water of about anxious to produce copies of such prints mechanically, he conceived 90° to too° F., and the paper of the tissue, loosened by the gelatin the idea of transferring the greasy ink impression to stone, and solution next it becoming soluble, can be stripped off, leaving the multiplying the impressions by See also:

• MECHANICAL

mechanical lithography .

Following image (reversed as regards right and left) on the flexible support. very closely upon Asser, J . W . See also:

• OSBORNE

Osborne of See also:

• MELBOURNE
• MELBOURNE, WILLIAM LAMB, 2ND VISCOUNT (1779-1848)

Melbourne made a An application of warm water removes the See also:

• REST (O. Eng. rest, reste, bed, cognate with other Teutonic forms, e.g. Ger. Rast, Riiste, rest, and probably Gothic Rasta, league, i.e. resting or stopping place)

rest of the soluble similar application; his process is described by himself in the gelatin and pigment . When dried the image is transferred to its Photographic See also:

• JOURNAL
• JOURNAL (through Fr. from late Lat. diurnalis, daily)

Journal for See also:

• APRIL

April 186o as follows: " A negative is permanent support . This usually consists of white paper coated produced in the usual way, bearing to the original the desired ratio . with gelatin and made insoluble with chrome alum, though it may . A positive is printed from this negative upon a sheet of be mixed with See also:

• BARIUM (symbol Ba, atomic weight 137'37 [0=16])

barium sulphate or other similar See also:

• PIGMENTS (Lat. pigmentum, from pingere, to paint)

pigments . This (gelatinized) paper, so prepared that the image can be transferred to transfer-paper is made to receive the image by being soaked in hot stone, it having been previously covered with greasy printer's ink. water till it becomes slimy to the See also:

• TOUCH (derived through Fr. toucher from a common Teutonic and Indo-Germanic root, cf. " tug," " tuck," O. H. Ger. zucchen, to twitch or draw)

touch; and the surface of the The impression is developed by washing away the soluble matter damped print is brought into contact with the surface of the re- with hot water, which leaves the ink on the lines of print of the transfer-paper, in the same manner as was done with the flexible See also:

• MAP
• MAP (or MAPES), WALTER (d. c. 1208/9)

map or engraving." The process of transferring is accomplished in support and the carbon-tissue . When dry the retransfer-paper the ordinary way . See also:

• EARLY
• EARLY, JUBAL ANDERSON (1816-1894)

Early in 186o See also:

• COLONEL (derived either from Lat. column, Fr. colonne, column, or Lat. corona, a crown)

Colonel See also:

• SIR

Sir H . See also:

• JAMES
• JAMES (Gr. 'IlrKw,l3or, the Heb. Ya`akob or Jacob)
• JAMES (JAMES FRANCIS EDWARD STUART) (1688-1766)
• JAMES, 2ND EARL OF DOUGLAS AND MAR(c. 1358–1388)
• JAMES, DAVID (1839-1893)
• JAMES, EPISTLE OF
• JAMES, GEORGE PAYNE RAINSFOP
• JAMES, HENRY (1843— )
• JAMES, JOHN ANGELL (1785-1859)
• JAMES, THOMAS (c. 1573–1629)
• JAMES, WILLIAM (1842–1910)
• JAMES, WILLIAM (d. 1827)

James, R.E., bearing the gelatin image can be stripped off the flexible support, F.R.S., brought forward the See also:

• SOUTHAMPTON
• SOUTHAMPTON, EARL OF
• SOUTHAMPTON, HENRY WRIOTHESLEY, 3RD EARL OF (1J73—1624)

Southampton method, of photo-lithowhich may be used again as a temporary support for other pictures. graphy, which had been carefully worked out by See also:

• CAPTAIN (derived from Lat. ca put, head, through the Low Lat. capitanus)

Captain de Courcy If a reversed negative be used the image may be transferred at once See also:

• SCOTT, ALEXANDER (fl. 1550)
• SCOTT, DAVID (18o6-1849)
• SCOTT, MICHAEL (1789-1835)
• SCOTT, ROBERT (1811-1887)
• SCOTT, SIR GEORGE GILBERT (1811-1878)
• SCOTT, SIR WALTER, BART
• SCOTT, WILLIAM BELL (1811-1890)
• SCOTT, WINFIELD (1786-1866)

Scott, R.E . The " papyrotype process " was published by Abney to its final support instead of to the temporary flexible support, in 1870 (see LITHOGRAPHY and PROCESS) ..

which is a point of practical value, since single-transfer are better than double-transfer prints . I Printing with Salts of See also:

• IRON [symbol Fe, atomic weight 55.85 (0=16)]

Iron.—Sir John See also:

• HERSCHEL, CAROLINE LUCRETIA (1750-1848)
• HERSCHEL, SIR F
• HERSCHEL, SIR FREDERICK WILLIAM (1738-1822)
• HERSCHEL, SIR JOHN FREDERICK WILLIAM, BART

Herschel and See also:

• ROBERT
• ROBERT (1275—1343)
• ROBERT, HUBERT (1753-1808)
• ROBERT, LOUIS LEOPOLD (1794-1835)

Robert See also:

• HUNT, ALFRED WILLIAM (183o-1896)
• HUNT, HENRY (1i73-1835)
• HUNT, HENRY JACKSON (1819-1889)
• HUNT, JAMES HENRY LEIGH (1784-1859)
• HUNT, ROBERT (1807-1887)
• HUNT, THOMAS STERRY (1826-1892)
• HUNT, WILLIAM HENRY (1790—1864)
• HUNT, WILLIAM HOLMAN (1827-1910)
• HUNT, WILLIAM MORRIS (1824-1879)

Hunt entered into various methods of printing with salts of iron . At I The first See also:

• NOTICE

notice on See also:

• RECORD (Lat. recordari, to recall to mind, from cor, heart or mind)

record of coloured light impressing its the present time two or three are practised, being used in See also:

• DRAUGHTS (from AS. dragan, to draw)

draughts- men's offices for copying tracings (see SUN-COPYING), Photo-mechanical Printing Processes.—Poitevin claimed to have discovered that a film of gelatin impregnated with potassium bichromate, after being acted upon by light and damning, would receive greasy ink on those parts which had been affected by light . But See also:

• PAUL
• PAUL (PAULUS)

Paul Oreloth seems to have made the See also:

• DISCOVERY

discovery previous to 1854, for in his patent of that year he states that his designs were inked with printing ink before being transferred to stone or See also:

• ZINC

zinc . C . M . Tessie de Motay (in 1865) and C . R . Marechal of See also:

• METZ

Metz, however, seem to have been the first to produce half-tones from gelatin films by means of greasy ink . Their See also:

• GENERAL
• GENERAL (Lat. generalis, of or relating to a genus, kind or class)