May 6, 1947. A. P. H. TRIVELLI ETAL 2,419,975 INCREASING SPEED AND CONTRAST OF PHOTOGRAPHIC EMULSIONS Filed Aug. 26, 1943

H| | | | | | | | | | ||

| | | | | | | | | IF | | | | | | | | | | III

ADRIAN PH, TRIVELLI MVILLIAM. F. SMITH INVENTORS "6 Sé. Af Patented May 6, 1947 2,419,975 UNITED STATES PATENT OFFICE 2,419,975 INCREASING SPEED AND CONTRAST OF POTOGRAPHICEMULSIONS Adrian P. H. Triveli and William F. Smith, Rochester,Company, N.Y.,Roehester, assignors N. Y., to a Eastman corporation Kodak of -New Jersey Application August 26, 1943, Serial No. 500,088 16 Claims. (Cl. 95-6) 2 This invention relates to photographic emul material but are used only to fog all of the unex Sions and particularly to a method for increas posed silverhalide. ing the Speed and cohtlast of Stich emulsions. It is an object of the present invention to pro The invention relates to the use of hydrazine vide an improved method for sensitizing photo and related compounds in a photographic proceSS. graphic silver halide emulsions. A further object Hydrazine and hydrazine derivatives have been is to provide a new method for increasing the used in photographic emulsions or developers for speed of photographic silver halide emulsions. many purposes. One Well known use of hydrazine A still further object is to provide a new method compounds in photographic emulsions is that of for increasing the contrast of photographic silver a halogen acceptor or halogen absorber. During 0 halide emulsions. A further object is to provide the exposure of a sensitive silver halide emulsion, a new method for processing photographic silver the silverhalideis thought to release halogen such halide emulsions to effect improved properties as bromine or chlorine and the sensitivity of the in the resulting image. Other objects will appear material is improved if the halogen thus released from the following description of our invention. is immediately combined With a compound which 5 These objects are accomplished by developing prevents it from recombining with silver. The an undeveloped silver halide photographic emul use of hydrazines for this purpose is described in sion, after exposure, at a pH of about 9.5 or higher Caldwell U. S. Patent 956,567. This effect of in the presence of a hydrazine, hydrazine Salt, or absorbing or accepting halogen is manifested hydrazine derivative of the general formula: only during exposure of the sensitive material. 20 The hydrazine or other compound used in this way is intended to be used tip during the exposure of the Sensitive material and it is customary to remove the unused compound prior to develop where at least two R.'s are hydrogen atoms and ment. 25 the remainder are carbon radicals, more Spe Hydrazine derivatives have also been used as cifically an aliphatic radical, -a, heterocyclic anti-foggants in sensitive emulsions. This use is radical, or a carbohyl group directly connected described in Sheppard and Wightman U.S. Patent to an aliphatic carbon atom of a carbon radical, 1,763,990. When used for this purpose, the hy a heterocyclic carbon atom of a carbon radical, drazines prevent the formation of emulsion fog 30 an oxygen atom of a carbon radical or a nitro at the time of exposure of the Sensitive material gen atom of a carbon radical. or shortly before or thereafter. They have no The drawing illustrates typical sensitometric function in the development of the exposed mate curves showing the improvement obtained by our rial. invention. Hydrazines have also been used in photographic 35 We secure an improvement in the sensitivity emulsions to increase the infra-red speed and characteristics, that is, the speed or contrast, or contrast of the material as described in Trivelli both, of photographic material by developing the and Carroll U. S. Patent 2,245,236. When used exposed material in the presence of a hydrazine in this way the hydrazines act in the infra-red or a compound related to hydrazine. It is in region of optically Sensitized material. It was not 40 portant that these compounds be present at the known that an increase in speed and contrast in time of photographic development since the effect the visible and ultra-violet regions of the spec which we obtain is a development effect. Our trum could be obtained by the use of these mate compounds may, accordingly, be added to the rials. emulsion or to the developer as long as they are Hydrazines have also been used in photographic 45 present during development of the exposed mate developers for two purposes. They have been rial. Prior users of hydrazines in the photo graphic emulsion have sought to obtain benefits used as the developing agent, and have also been from their use, during exposure of the material used in fogging second developers to render re and not during development. The only excep Versal exposure of the material unnecessary. 50 tion is the Trivelli and Carroll U. S. Patent When used in this way they do not affect the speed 2,245,236, referred to above, and in this case the or contrast of the material. Since the effective effect is limited to the red alad infra-red region speed and contrast are deterrained by the original of the spectrum. When the hydrazines employed development, the hydrazines in the second de in the prior art have been incorporated in the veloper do not affect these characteristics of the 55 developing Solution, they have been used either 2,419,975 3 as the developing agent or as the fogging agent 12. in a reversal developer and would not effect an improvement in sensitometric properties of the No-C-NHNHHC) photographic material. p-Nitrophenylhydrazine hydrochloride The following classes of compounds have been 5 13, found suitable for use according to our invention: ey -sul ISO Hydrazines of the general formula: K CY - O a-Methyl-a-pheny hydrazine sulfate in which R, is hydrogen, an acid ester group or a Hydrazides (acyl hydrazines) having the gen heterocyclic group. The following compounds eral formula: illustrate this class. 1. NHNH2.2EIC) Hydrazine hydrochloride 5 2. NENHO where R is an alkyl radical or a chemical bond to Hydrazine hydrate a similar radical and R' is an aryl radical. 3. NH2NEICO OCEI. Ethylhydrazine carbonate 20 14 l, 4. A/ C-NHN c? Yohic ONEN OO a-Acethydrazide pyridinium chloride YN 25 2-benzothiazolylhydrazine 5.

n 30 c? CICONNIC O-K X 2-quinolyhydrazine 6-Benzoylacethydrazidopyridinium chloride 6. NHNH C 35 16, ?--se ONEINH O). l N 2d–{ X 4-hydrazinoquinaldine CE The product made, by adding ethyl chloro 7. 40 acetate to 2-phenyl pyrimidazole, followed by treatment with hydrazine. The structure is preSunably as given ? NEINE 17. CoNHNH, Na - * 2-pyridylhydrazine 45 { >NC N CONNE Alkyl or aryl hydrazines of the general formula: Yir R Malonyl dihydrazide pyridinium bromide 8. NE-NE-R O NH-NY N 50 R where R and R are alkyl or aryl groupS. n The following compounds illustrate this group: of YoHoN ONENE-X X 8. 55 B-Phenylacethydrazidopyridinium chloride Ho-(D-NHNH, HCI 19. CH p-Hydroxyphenylhydrazine HCl { X-CH-)-CH,C ONNE Cl 9. CH3 &H, Y-NH.H Cl 60 Benzyl-dimethyl-acethydrazido-ammonium chloride Ch? 20. CONHNH as Dimethyl hydrazine hydrochloride of, 10. 65 Yo ONEINH No-K X-NHNL, Malonic acid dihydrazide NO 21. CONN 2,4-dinitrophenylhydrazine ONNE 11. 70 Oxalic acid dihydrazide N-NEHC 22. CH-CONHNH d-c ONEINE {X-ri, &B-c ONNE a-Benzyl-a-phenylhydrazine hydrochloride 75 Aconitic acid trihydrazide 2,419,975 6 Typical compounds are as follows: K O-H-conHNE, 84 . . . . &H,- CONHN Phenylsuccinic dihydrazide 5 Semicarbazides, carbohydrazides and amino ah, biurets having the formula: of YoH,conENEconHN=c Chs RY--NHNH, 10 The acetone derivative of 26 R? 35 r 2 where R is hydrogen and R' is hydrogen, NH2 which may or may not be substituted, an aryl 15 CHs GHs t radical, or a carboxylic acid amide radical. c? YoHooNHN=5 (-NHN.coon? Yo 24. NHCONHNH2.HCl The diacetyl-derivative of #14 Semicarbazide-hydrochloride 36. ZN 25. NEINEICONEINEI.HCl 20 Carbohydrazidehydrochloride l c? YoHooNHN=CHCHOHOHOHCHOHCHOHCH-OH 26. The glucose derivative of #4 25 37. C3 CH SN M. N. Cl CHCONEINHCONHNH KD-CH-)-cisconHN=c(w bH, YoH. :Cl Acetcarbohydrazide pyridinium chloride 30 Acetone-derivative of #19 The increase in sensitivity or contrast which We obtain by the introduction of hydrazines to 27. ? the emulsion or developer, whether as water soluble or as Water-insoluble compounds increases X conHNHOONHNE, 35 considerably With increase in pH of the developer. Bir YC t The pH of the developer used with our materials CONHNHCONHNH should be about 9.5 or higher. With a developer having a pH of 12.8, the use of hydrazine in a Malonyl-dicarbohydrazido pyridinium bromide silver chlorobromide emulsion produces a strong 28. 40 effect by which the gamma can be increased from 3 to a gamma of iO or higher. With some emul NNEC oNH-O-C) Sions a gamma, as high as 24 has been obtained. 4-(p-chlorophenyl)-semicarbazide Speed increase Without gamma increase, Speed increase with gamma increase and gamma in 29. NaNHCONH- 45 crease without speed increase have been observed. In addition to pH, the pAg or silver ion con &H, centration, of the emulsions to which an active compound is added, is an important factor in 4-(o-tolyl)-semicarbazide controlling the effect which we obtain. Higher 30. 50 silver ion concentrations tend in general to in NENECONH- - Cl crease the effect as do high pH's. It is also important not to add carbonyl hardening agents s to the emulsion. If present in equimolar con centrations such hardeners usually destroy the 4-(4-chloro-2'-methyl-phenyl)-semicarbazide 55 effect probably due to hydrazone formation. The 3. /N explanation of this apparent inconsistency is that the hydrazones listed above are believed to decompose to release hydrazine or hydrazine de N/ CONHNH, rivatives. The hydrazones formed by reaction of the carbonyl hardening agents with gelatin are off, Yo-( )-CH, 60 not readily decomposed and therefore do not improve the sensitimetric characteristics of the N-methyl-2-carbohydrazylpyridiniump-toluenesulfonate emulsion. Chrome alum may, however, be used as a hardening agent. The pAg of the emulsions 32, NiI2.N.E.C.O.N.E.CONH.N. 65 which we use lies in the range of 6.0 to 9.5. Diaminobiuret Emulsions of various types such as chloride, bro mide, bromoiodide, and chlorobromide may be 33. NH.C.O.N.H.C.O.N.H.NEI, employed. The effect has been found to be Aminobiuret especially noticeable in the case of high contrast 70 emulsions. Hydrazones. These compounds contain the The increase in sensitivity or contrast which grouping: we produce is obtained with any type of develop ing agent such as the phenolic type, such as monomethyl-p-aminophenolsulfate, catechol, p -C-E-NE-Na-O 75 hydroquinone and pyrogallol. A developer of the 2,419,975 7 8 following composition such as Kodak Formula drazine dihydrochloride in an amount of 0.06 D-8 which has a pH of 12.8 is Suitable. gram to 1 liter of D-8 developer having the Com position stated above. A normal Speed gelatino Sodium sulfite (desiccated).------grams-- 90 silver bromide emulsion was exposed and de Hydroquinone------do---- 45 veloped for 1% minutes in the developer, a com Sodium hydroxide ------do---- 37 parison being made with the developing Solution Potassium bromide------do---- 30 without the hydrazine. The Speed contrast and Water to ------liters-- 1 fog recorded in the two cases were as follows, the A developer of the following composition, such Speed being measured as ten times the reciprocal as Kodak Formula, D-19, which his a pH of 10.2, 10 of the inertia. is also suitable: Monomethyl-p-aminophenol sulfate-grams-- 2.2 Sps Gamma Fog Hydroquinone------do---- 9 Sodium Sulfite (desiccated).------do---- 96 5 Check------9.55 2.3 ... 07 Sodium carbonate (desiccated).------do---- 48 -Hydrazine dihydrochloride (0.06 g. per l. Potassium bromide------do---- 5 D-8 developer)------25.0 9.4 .06 Water to ------liters.- 1 The following tables show the change in Speed It has been found that the novel effect pro and contrast obtained When various compounds duced by hydrazine or its derivatives may be ex 20 tended to developers of normal pH, by regulating according to our invention were added to a nor the concentration of sulfite in the developer. In mal speed chlorobromide emulsion: developers of pH 10 or higher, such as Kodak Concen Formula, D-19, the concentration of sulfite may tration, be high. With developers of lower pH the con 25 Compound Gigi,per 10/i Gamma Fog Centration of Sulfite must be decreased in order to achieve the advantages of the use of hydrazine Emulsion Or its derivatives. For example, a developer of the following composition, which has a pH of Semicarbazide HCl------{ 18 38 8. 0 8 4.15 10 9.7, and contains hydrazine dihydrochloride is 30 1.0 18, 4.40 .08 Suitable for increasing the Speed of Silver halide 0------2.0 14 6.15 .10 3.0 17 7.30 .09 emulsions. O 2.5 3.81 .08 4.0 19.0 7.4 .09 Monomethyl-para-aminophenolsulfate 6.0 18.0 11.3 .07 D 8.0 22.0 11.0 .07 --granS- 2.2 35 0------10.0 18.0 14.0 .08 p-Hydroquinone ------do---- 8.8 2.0 7.0 9.0 ... 07 Sodium sulfite (desiccated).------do---- 16.0 14.0 22.0 8.6 ... 07 Potassium bromide------do---- 5.0 Hydrazine dihydrochloride------{ 16.033 22.53: 17.053 :.06 Sodium carbonate------do---- 48.0 0. 16 4.5 .06 Hydrazine dihydrochloride------do---- 0.2 1.0 8.5 6.6 .06 40 Ethyl hydrazine carbonate...... 1.5 20.5 6.8 ,06 6-Nitlobenzinidazole nitrate------do---- 0.05 2.0 22.5 7.0 .06 Water to------literS.-- 1 4.0 23.0 12.6 .06 0. 5.0 6.8 .06 The improved effect obtained by controlling the 4-(p-chlorophenyl)-semicarbazide 3. 8 E. : ; i 9: Sulfite concentration of the developer is not lim 10.0 15.0 9.6 .04 45 0 8.0 4.5 .08 ited to the particular formula stated above. The 3.0 18.0 6.0 07 formula, which may be employed depends upon 4-(o-tolyl)-semicarbazide------5.0 19.5 9.4 07 7.0 24.5 3.2 .05 the type of emulsion and the sensitometric char 10.0 23.5 9.0 .06 acteristics Sought. The anti-foggant employed N-chloro-N-pyridinoacetic acid 0 16.0 4.5 .06 carbohydrazide------4.0 23.5 6.4 .16 in this developer is not essential although its use 50 1-(N-chloro-N-pyridine acetic O 16.0 4.5 .06 is desirable for controlling fog and development acid)-4-carbohydrazone------4.0 22.5 6. .14 time. The hydrazine compound may also be in 2-pyridyl hydrazine.------33 SE 3: Corporated in the emulsion and the improved ef as-Dimethyl hydrazine HC----- 9.6 G. E.; : fect obtained by development in a developing - 0. 12.3 5.1 .13 Solution of low Sulfite content. 2,4-Dinitrophenyl hydrazine.----- 4.2 16.5 5.1 .13 55 a-Benzyl-a-phenyl hydrazine O 13.5 5.0 .26 The amount of hydrazine or hydrazine deriva HCl------.042 18.0 4.5 .21 tive added to the developer differ depending upon p-Nitrophenyl hydrazine HCl--- al 5. : O 3: the composition of the hydrazine and of the de Veloper enployed. Amounts in the range of 0.01 gram to 5 grams per liter of developer in general The emulsions developed according to our in are Satisfactory. 60 vention may be exposed by any kind of actinic When the compounds are added to the emul radiation, but in certain cases we prefer to em Sion, they may be added before, during or after ploy light of Wave-length shorter than infra-red, second ripening. A necessary requirement is that is, visible light, ultra-violet light, X-rays or that they be present during the development of gamma rayS. Charged particles such as oz-rays, the exposed material. It is also essential to our 65 g-rays and cosmic rays may also be used for the invention that the hydrazine compounds should eXpOSure, not function as anti-foggants in the emulsion. The improvement secured by our invention The amounts used in the emulsion will vary with Will be more readily apparent by reference to the the composition of the hydrazine compound and accompanying drawing which shows typical sensi of the emulsion but the amount used should not 70 tometric curves of eXposed and developed photo be sufficient to cause fog. In general, amounts graphic material. These curves were made by ranging from 0 to 2 grams per pound of wet plotting density against the logarithm of the emulsion ale Satisfactory. exposure in the Well known manner. Curve A The following table shows the improvement in shows the result of exposing and developing a Speed and gamma obtained upon addition of hy 75 normal Speed chlorobromide emulsion for 1A, 2,419,975. 9: O minutes' in D-8: developer atti. 659 F. Curves B: undeveloped silver'halide emulsion-layer to said. Was: obtained from a similar emulsion. exposed: radiation. and developing it. with a phenolic de and developed under: the same conditions, as the veloping-agent at a. pH of at least approximately emulsior resulting is curve A, but with. an ad - 9.5-in a developing: solution selected from... the dition of 0.625 gram per liter of emulsion of Ortho 5. class of developing solutions containing: an ap tolyl semicarbazide, Curve C was obtained withi. preciable amount of sulfite up, to 16:grams-per. an emulsion similar: to that of Curve. A but withi. liter when the pH is between 9.5 and 9.7; and the addition of 0.9375 gram per: liter of ennulsion, containing more than 16 grams per liter of:sulfite of Orthotolyl semicarbazide. It will be noted, When the pH is higher-than 9.7 in the presence of that in curves B and C the speed of the emulsion. 0: a. Semicarbazide. has been increased and the contrasti, has also 4. The method of increasing the speed; of a., been increased: No increase in fog is evident.in Silvei". halide photographic.layer. With respect to these. Curves. The untreated emulsion...showed a radiation, consisting of light of wave. length. 10/i- speed of: 8.9, a contrast, of 3.9, and a fog. Shorter than red, which comprises exposing an density of .04. The... emulsion, from: which curve: 5. undeveloped silver halide emulsion layer, to said: B was obtained showed a Speed of 94 and a game radiation and developing it. with a phenolic des. mar of 63. The emulsions from which: curve, C. veloping agent at a pH of at least approximately. was obtained showed a speed of:9.6- andfar-gamma; 9.5" in a developing. solution, selected from: the of 83. The fog density in all three emulsions class. of developing. Solutions containing an apa. Was the same 20. preciable amount of sulfite up to 16 grams. per It will be understood that the examples and . liter. When the pH is between 9.5 and 9.7, and modifications included herein are illustrative only Containing more than 16 grams per liter of sul. and that our invention is to be: taken as: limited fite when the pH is higher than 9.7 in the press Only-by-the-scope of the appended; claims: ence of hydrazine...dihydrochloride. We claim: 5. The method of increasing: the speeds of ai. 1. The method of improving. the sensitivity. 25. Silverhalide photographic layer, with respect to: characteristics of a silver halide- photographic radiation consisting of light of wave lengthshorter. layer. With respeet to radiation consisting-of light than , red, which comprises exposing: an under. of wave length shorter than red, which comprises: Veloped Silverhalide emulsion layer to said radia exposing - an undeveloped silver halide emulsior 30 . tion: and developing it with a phenolic develops layer to said “radiation and developing-iti with:a: ing agent at a pH of at least approximately.95. phenolic developing agent- at a pH of at least in a developing Solution selected from the class. approximately 9.5-in; a. developing. Solution's se-- of developing Solutions containing an appreciable: lected from the class of developing solutions-con amount. Of Sulfite up to 16 grams: per liter, whent. taining an appreciable amount of sulfite up to the pH is between 9.5. and 9.7, and containing: 16 grams-per-liter when the pH is between 9.5 more than 16 grams per: liter. of sulfite when. and 9.7, and containing more than 16 grams per the pHis higher than 9.7 in the presence of semi liter of sulfite when the pH is higher than 9.7, carbazidehydrochloride in the presence of a compound selected from the 6. The method: of increasing: the speed; to: group consisting of -hydrazine-compounds-of-the 48) . actinic radiation of a silverhalide photographics: general formula: layer; which comprises incorporating an aliphatic. acyl hydrazine in a gelatino-silverhalide emuls Sion, coating the emulsion on a support, exposing: the undeveloped layer to actinic radiation, and . 45: developing: it with a phenolic developing: agent. at a pH of at least-approximately 9.5iina.developa. where at least two R's are hydrogen atoms and ing. Solution selected from the class-of developing. when less than 4 R's are hydrogen atoms, there Solutions: containing an appreciable amount of mainder, are selected from the class.consisting of Sulfite up to 16 grams per liter. When the pH is: aliphatic radicals, heterocyclic, radicals, and a 50 between 9.5 and 9.7, and containing more... than carbonyl group directly, connected to a member 16:grams per liter of sulfite when the pHis higher. of the class, consisting of an aliphatic carbon than 9.7 in the presence of said hydrazine, . aton of a carbon radical, a heterocyclic carbon 7. The method of increasing the speed of a. aton of a carbon radical, an oxygen atom of a Silver halide-photographic layer with respect to: carbon-radical, and a nitrogenatom of a carbon 55 radiation consisting of light, of wave length radical, and the salts of said compounds, said shorter than red, which comprises incorporating : compound, having no fog inhibiting action on a Semi-carbazide in a gelatino-silver emulsion, Said emulsion. coating the-emulsion on a support, exposingithe: 2. The method of increasing the speed to undeveloped layer to said radiation and developic actinic radiation of a silver halide photographic 60. ing it with a phenolic developing agent at a pH layer; which comprises exposing an undeveloped of at least approximately 9.5 in a developing-soltists silverhalide emulsion layer-to-actinic-radiation tion containing an.appreciable amount of sulfite's and developing it with a phenolic - developing up to 16-grams per liter when the pH-is-between agent at a pH of at least approximately 95 in 9:5 and 9.7, and containing more than 16 grams: a developing solution selected from the class-of-65 per liter of sulfite when the pH is higher than 97 developing solutions containing an appreciable in the presence of said semi-carbazide. amount of sulfite up to 16 grams per liter When 8. The method of increasing the speed of a the pH is between 9.5 and 9.7, and containing silver halide photographic layer with respect to more than 16 grams per liter of sulfite when the radiation consisting of light of wave length pH is higher than 9.7 in the presence of an ali- 70 shorter than red, which comprises incorporating phatic acyl hydrazine. hydrazine dihydrochloride in a gelatino-silver 3. The method of increasing the speed of a halide emulsion, coating the emulsion on a Sup Silver halide photographic layer with respect to port, exposing the undeveloped layer to actinic radiation consisting of light of wave length radiation and developing it with a phenolic de shorter than red, which comprises exposing an 75 yeloping agent at a pH of at least approximately 2,419,975 11. 12 9.5in a developing solution selected from the class silver halide emulsion layer to actinic radiation of developing solutions containing an appreciable and developing it with a phenolic developing agent amount of sulfite up to 16 grams per liter when in a developing solution having a pH of at least the pH is between 9.5 and 9.7, and containing approximately 9.5 and containing a semicarba more than 16 grams per liter of sulfite when the zide hydrochloride and being Selected from the pH is higher than 9.7 in the presence of Said class of developing Solutions containing an ap hydrazine dihydrochloride. preciable amount of sulfite up to 16 grams per 9. The method of increasing the speed of a liter when the pHis between 9.5 and 9.7, and con silver halide photographic layer. With respect to taining more than 16 grams per liter of sulfite radiation consisting of light of wave length shorter 10 when the pH is higher than 9.7. than red, which comprises incorporating semi 14. A gelatino-silver halide emulsion capable of carbazidehydrochloride in a gelatino-silver halide exhibiting improved speed and contrast charac emulsion, coating the emulsion on a Support, ex teristics when exposed and developed in a devel posing the undeveloped layer to Said radiation oping Solution having a pH of at least approxi and developing it With a phenolic developing agent 5 mately 9.5, comprising a gelatino-silver halide at a pH of at least approximately 9.5 in a develop emulsion having therein an appreciable amount, ing solution selected from the class of developing not greater than 2 grams per pound of wet emul solutions containing an appreciable amount of Sion, or a semi-carbazide. sulfite up to 16 grams per liter when the pH is 15. A gelatino-silver halide emulsion capable between 9.5 and 9.7, and containing more than 20 of exhibiting improved speed and contrast char 16 grams per liter of Sulfite when the pH is acteristics when exposed and developed in a de higher than 9.7 in the presence of said Semi veloping Solution having a pH of at least approxi carbazide hydrochloride. mately 9.5, comprising a gelatino-silver halide 10. The method of increasing the speed to emulsion having therein an appreciable amount, actinic radiation of a silver halide photographic 25 not greater than 2 grams per pound of wet emul layer which comprises exposing an undeveloped Sion, of an aliphatic acyl hydrazine. silver halide emulsion layer to actinic radiation 16. A gelatino-silver halide emulsion capable of and developing it with a phenolic developing exhibiting improved speed and contrast charac agent in a developing Solution having a pH of at teristics when exposed and developed in a devel least approximately 9.5 and containing an ali 30 oping Solution having a pH of at least approxi phatic acyl hydrazine and being selected from mately 9.5, comprising a gelatino-silver halide the class of developing Solutions containing an emulsion layer having uniformly dispersed therein appreciable amount of Sulfite up to i6 grams pel an appreciable amount, not greater than 2 grams liter when the pH is between 9.5 and 9.7, and per pound of Wet emulsion, of an aryl Semi-car containing more than 16 grams per liter of sulfite 35 bazide. when the pH is higher than 9.7. ADRIAN P. H. TRIVELLI. 11. The method of increasing the speed to WILLIAM. F. SMITH. actinic radiation of silver halide photographic layer which comprises exposing an undeveloped REFERENCES CITED silver halide emulsion layer to actinic radiation 40 and developing it with a phenolic developing The following references are of record in the agent in a developing solution having a pH of file of this patent: at least approximately 9.5 and containing a semi UNITED STATES PATENTS carbazide and being selected from the class of developing Solutions containing an appreciable 45 Number Name Date amount of sulfite up to 16 grams per liter when 956,567 Caldwell ------May 3, 1910 the pH is between 9.5 and 9.7, and containing 1,082,622 Caldwell ------Dec. 30, 1913 more than 16 grams per liter of sulfite when the 1,560,240 Jelley ------Nov. 3, 1925 pH is higher than 9.7. 1,763,990 Sheppard et al.------June 17, 1930 12. The method of increasing the speed to 50 2,127,573 Sheppard et al. ----- Aug. 23, 1938 actinic radiation of a silver halide photographic 2,220,929 Kirby ------Nov. 12, 1940 layer which comprises exposing an undeveloped 2,245,236 Trivelli et al. ------June 10, 1941 silver halide emulsion layer to actinic radiation 2,311,098 Swan et al. ------Feb. 16, 1943 and developing it with a phenolic developing agent 2,196,734 Marriage ------Apr. 9, 1940 in a developing Solution containing hydrazine di 2,266,442 Schinzel ------Dec. 16, 1941. hydrochloride at a pH of at least 9.5, said devel 2,286,662 Weyde et al. ------June 16, 1942 oping Solution being selected from the class of 2,309,492 Albers et al. ------Jan. 26, 1943 developing solutions containing an appreciable 2,339,213 Woodward et al. ---- Oct. 16, 1939 amount of Sulfite up to 16 grams per liter when OTHER REFERENCES the pH is between 9.5 and 9.7, and containing 60 more than 16 grams per liter of sulfite when the Carroll, "Sensitization of Photographic Emu pH is higher than 9.7. sions by Colloidal Materials,” “Bureau of Stand 13. The method of increasing the speed to ards Journal of Research,' vol. I, October, 1928, actinic radiation of silver halide photographic pp. 565-588, p. 584 cited (Photostat Copy in layer which comprises exposing an undeveloped 65 Division 7.)