US2288226A - Photographic emulsion - Google Patents

Description

Patented June 30, 1942 PHOTOGBAPHIC EMULSION Burt H. Carroll and Charles F. H. Allen, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation oi New Jersey No Drawing. Application February 29, 1940, Serial No. 321,594

20 Claims. (01. 95-1) This invention relates to photographic emulsions and more particularly to photographic emulsions of the silver halide type.

It is known that the inherent sensitivity of photographic silver halide emulsion (whether spectrally sensitized or not) can be increased, and there has been a constant effort to produce higher and higher speeds in photographic emulsions. For example, it is known that the speed of gelatino-silver-halide emulsions can be enhanced by an extended digestion or ripening of the emulsion. It is also known that the speed of silver halide emulsions (spectrally sensitized or not) can be enhanced by incorporating in the emulsions compounds containing a divalent atom of the sulfur group directly joined by'a double bond to a single metalloid atom to which is attached at least another group of atoms. Examples of such compounds are allyl isothiocyahate and allylthiourea.

More recently it has been found that the speed of photographic silver halide emulsions (whether spectrally sensitized or not) can be increased by incorporating in the emulsions a cationic surface active substance of the ammonium salt type. (See the copending application of Burt H. Carroll, Serial No. 321,595, filed of even date herewith, now United States Patent 2,271,623,'dated February 3, 1942.) The speed increases attainable by the method of Carroll are complementary to the speeds attainable by the prior methods.

A difficulty encountered with the aforesaid method is that the surface active substances appear to diffuse to a greater or lesser degree from the emulsions into the film supports upon which the emulsions are usually coated, i. e., the ordinary film supports of plastic materials, such as cellulose nitrate, cellulose acetate or polyvinyl acetate resin for example, with the result that their effect on the photographic emulsion may be decreased.

We have now found that polyonium salts (whether of the surface active type or not) the group consisting of quaternary ammonium, quaternary phosphonium and ternary sulfonium salt groups, sensitize photographic silver halide emulsions (whether spectrally sensitized or not) and have the added advantage of not diffusing appreciably from the emulsions into the film support upon which the emulsions are usually coated.

As in the aforesaid method of Carroll, the speed increases attained by our newmethod are complementary to the speed increasesthat can be attained by the prior methods.

The polyonium salts act on the emulsion in unknown manner to increase its effective sensitivity. As a result, the sensitivity is increased by about the same amount at any wavelength within the range of its spectral sensitivity, although in spectrally sensitized emulsions there is frequently observed an appreciable increase in relative sensitivity for longer wavelengths. Inasmuch as the silver ion and the hydrogen ion concentration in our new emulsions appear to undergo little or no change by virtue of the presence of the polyonium salts, we shall refer to the action of the polyonium salts as a kind of supersensitization, and we shall refer to mixtures of the polyonium salts and spectral sensitizers (sensitizing dyes) as combinations, although we do not intend to imply that the polyonium salts and the spectral sensitizers are chemically combined.

Our new supersensitized emulsions are an improvement over supersensitized emulsions known in the art. The increases in sensitivity which can be attained with supersensitizing combina- ,tions of dyes can be enhanced by our new methods. Furthermore, whereas with supersensitizing combinations of sensitizing dyes (see United States Patents 2,075,046; 2,075,047 and 2,075,048, each dated March 30, 1937), the supersensitizing" effect is confined more or less to a single spectral region, the supersensitization attained in our new emulsions extends throughout I the entire region in which the spectral sensitizer acts, (and is fairly uniform in degree throughout the entire region), while at the same time the sensitivity in the violet and blue region (where the spectral sensitizer does not act) it is also enhanced to about the same degree.

An object of our invention, therefore, is to provide new photographic emulsions. A further ob- III.

In the above general formulas R, R, R", R1

and R2 represent alcohol radicals, such as methyl, ethyl, n-primarybutyl, isoamyl, lauryl, or benzyl for example, Q represents the non-metallic atoms necessary to complete an organic heterocyclic nucleus, such as a pyridine nucleus, 9. pyrazole nucleus or a pyriminazole nucleus for example, X represents an anion (or acid radical), such as halide, p-toluenesulfonate, alkylsulfate or perchlorate for example and Z represents a bivalent organic radical such as the following for example:

' CH2CH2 ethylene CH2(CH2) aCH2- decamethylene -CH2-O-CHz(CHz) sCH2OCH2- decamethylene-bis-oxymethyl -CH2O-CH2-CH2OCH2 ethylene-bis-oxymethyl CH2CH2O) nCH2CH2l- (wherein n represents a positive integer) ,CH-z0(CHz)1l (wherein n represents a positive integer) CH2-CH2SCH2-CH9 0 CHCH2 -cmcnoi1onro-cnr-cm-ta o- H} Or the chain may also contain nitrogen, as will be apparent from Example 8 hereinafter set forth. When the two onium salt groups which are linked together by the bivalent organic radical, Z, are identical, the salt is a his onium salt:

in accordance with the definition in Chemical Abstracts, vol. 29, page 8867 (1935), vis. bis is used for like molecules united by a bivalent organic radical. In accordance with this definition, the compound is a bis compound whether the bivalent organic radical is, in itself, symmetrical or unsymmetrical.

We can also employ polyonium salts in which two onium salt groups are linked together by more than one bivalent organic radical. Examples of such salts are those which can be represented by the following general formula:

wherein R and R represent alkyl groups and X represents an acid radical.

In general, we have found that the polyammonium salts are superior to the polyphosphonium and polysulfonium salts. Among the polyammonium salts, the bis pyridinium quaternary salts, the his dimethylbenzylammonium quaternary salts and the bis diethylbenzylammonium quaternary salts are especially advantageously employed. The anion of the salt may be any anion, such as chloride, bromide, iodide, p-toluenesulfonate, perchlorate or alkylsulfate for example. Of course, introduction of halide anions into photographic silver halide emulsions alters the halide concentration in the emulsion and compensating changes in the emulsion may be desirable, if such ammonium salts are employed. For this reason, we ordinarily prefer to employ polyonium salts containing anions other than halides. Perchlorates and .p-toluenesulfonates are advantageously employed.

In accordance with our invention, the polyonium salts are incorporated in the emulsions in any suitable form, e. g. in the form of a solution in a suitable solvent, such as water or methyl alcohol.' The polyonium salts should be thoroughly incorporated in the emulsion.

In the case of spectrally sensitized emulsions, the polyonium salt can .be incorporated in the emulsion before, simultaneously with or after the sensitizing dye, although in some cases as hereinafter set forth, it is advantageous to incorporate the sensitizing dye before incorporating the polyonium salt. The methods of incorporating sensitizing dyes in emulsions are, of course, well known to those skilled in the art. Ordinarily, it is advantageous to employ a solution of the sensitizing dye in a suitable solvent, e. g. methyl alcohol; ethyl alcohol or acetone may be employed in cases where the solubility of the sensitizing dye in methyl alcohol is very low. sensitizing dyes are ordinarily incorporated in the washed, finished emulsions, and in accordance with our invention, the polyonium salts are advantageously also incorporated in the washed, finished emulsions. onium salts can be added to the emulsion during the preparation thereof, i. e. during the precipitation, the first digestion or the second digestion (ripening). After preparing the emulsions in the presence of the polyonium salts, the sensitizing dyes can be incorporated in the so-prepared emulsions.

The polyonium salts which may be used in our invention, as apparent from the foregoing generic description of these salts, may specifically include various elements and be. of several different chemical structures. Also, these polyonium salts may be produced by a number of However, the poly-- methods. The polyonium salts of this invention may be obtained from various sources, assuming, of course, they are of high purity and are otherwise satiaiactory for photographic use.

For a better understanding of our invention, and for the purposes of illustrating the details of some of the methods of preparation, a number of methods of preparation are described hereinafter. It will be noted that reference is made to certain copending applications wherein still further details and methods are disclosed. Hence, it is to be understood that our invention is not to be restricted in this aspect.

The preparation of his quaternary ammonium salts from alkylene dihalides and pyridine is described by Baer 8i Prescott in J. Am. Chem. Soc., 18, 988 and by Davidson in Ann. 121, 254. The preferred and improved preparation of his quaternary ammonium salts from alkylene-bisoxymethyl diesters is described in the copending application of C. F. H. Allen, Serial No. 321,596, of the comparable title Bis quaternary ammonium salts, filed of even date herewith. The preparation of his quaternary ammonium salts from p-xylylene dihalides is described by Manoukian in Ber. 34, 2089.

Bis quaternary ammonium and phosphonium salts of the character set forth above can be prepared by reacting a tertiary amine or a tertiary phosphine with an ester of a dihydric alcohol as the ester of halogen acids, p-toluene sulfonic acid, etc., halides or di-p-toluenesulfonates being advantageously employed. Typical dihalides are those corresponding to the above bivalent radicals, e. g.

Methylene dibromide Ethylene dibromide Decamethylene dibromide Ethylene-bis-oxymethyl chloride Decamethylene-bis-oxymethyl chloride ,c,fi-Dichlorodiethyl ether Chloromethyl-B-chlorethyl ether Chloromethyl-' -chloropropyl ether 5,p'-Dichlorodiethyl sulfide Typical tertiary amines which can be reacted readily with such alkyl salts of dihydric alcohols are pyridines (including the ordinary pyridine as well as substituted pyridines, e. g., e-picoline and a-(n-110Ily1) -pyridine) N-methylpiperidine, 1-,

.phenyl-3,5-dimethylpyrazole, 2-phenylpyriminpending application of Charles F. H. Allen and John W. Gates, Jr., Serial No. 321,598, entitled Polysulfonium salts, filed of even date herewith. The following examples illustrate the formation of his quaternary phosphonium salts and unsymmetrical onium salts. The parts given are parts by weight.

Emu: 1.Ethylene bis-ozymethyl triethylphosphonium chloride Exmru: 2.Tetramethylene-bis-orymethyl-triethylphosphonium bromide 6 parts of triethylphosphine and 6 parts of decamethylene bromide were mixed together and the mixture warmed slightly. A vigorous reaction set in and a white solid separated. After cooling, the reaction product was dissolved in 20 'parts of methyl alcohol and the resulting solution allowed to stand until the bulk of the alcohol had evaporated. The residue was diluted with 20 parts of diethyl ether and the white crystal,- line material which formed was filtered off and dried in the air. It melted at 158 C.

EXAMPLE 3.EthyZene-bis-o:cymethyl-a-pic0linium perchlorate To 1.9 parts of a-picoline was added 3.2 parts of ethylene-dioxymethyl chloride. vigorous reaction and the temperature rose rapidly. When cooled, a-tacky mass resulted which was essentially ethylene-bis-oxymethyl-u-picolinium chloride. The chloride was converted to the perchlorate by dissolving 4 parts of the former in 8 to 10 parts of methyl alcohol and treating with a solution of 2 to 3 parts of sodium perchlorate in 8 to '10 parts of warm water.

Ethylenedioxymethyl-a picolinium perchlorate is an oil which fails to solidify. It was separated from the aqueous-alcoholic mother liquors, washed with ether to remove any unchanged reactants and the last traces of ether removed by heating for a few minutes on the steam bath.

EXAMPLE 4.N,N'-trimethyZene-bis-2-undecylimidazolz'nium bromide To and two-tenths parts of 2-undecylimidazoline and 1 part of trimethylene bromide were heated 4 hours at -130 C. and cooled. The resulting wax was scrubbed four times with 100 parts of ether and dried. The yield of wax was 2 parts.

EXAMPLE 5. 1,8-octamethylene-bis N,N' -di methyl-2,2-imidazoliniu.m-p-toluenesuljonate To and five-tenths parts of 1,8'-octamethylenebis-2,2'-imidazoline, prepared according to a method given in U. S. Patent 2,155,877 from sebacic acid, ethylenediamine and ethylenediamine dihydrochloride, and 3.7 parts of methylp-toluenesulfonate were heated 2 hours at C. and cooled. The resulting wax was scrubbed four times with 100-part portions of ether and dried. The yield was 4 parts.

There was a Ethylene-bis-oxymethyl-bis- 2 In addition to the aforementioned type of polyonium salt used for improved 'supersensitiza tion in accordance with the herein described invention, there are still other types of salts which may be employed. These are derived from pyriminazoles, such as 2-phenylpyriminazoleand 2-methylpyriminazole (CH; for CsHs).

. The useful salts of such type compounds would preferably be the perchlorate or sulfonate, as already described. However, other derivatives. such as the bromide and the like may be employed. Examplesof useful salts are as follows:

zolium chloride phenylpyriminazolium perchlorate Ethylene-bis-Z-methylpyriminazolium p toluenesulfonate Tetramethylene. bis

bromide Still further illustrations of the pyriminazolium type compound are as follows:

EXAMPLE 6.Ethylene-bis-Z-methylpyrinzidazolium p-toluenesullonate Two and seven tenths parts of Z-methylpyrimidazole and 3.7 parts of bis-ethylene-p-toluenesulfonate were heated for 2 hours at 125 to 130 C. During this heating the reaction mixture solidified. At the end of this time, the reaction mixture was dissolved in hot alcohol, flltered-and precipitated from the cold filtrate by the gradual addition of ether. The yield of solid was 4.5 parts, melting at 268 to 270 C.

By a similar procedure, the following compounds were prepared: a

2 methylpyriminazolium M. P. Tetramethylene-bis-2-methylpyrimidazolium bromide 297-9" Ethylene-bis-2-phenylpyrimidazolium-ptoluenesulfonate An oil Decamethylene-bis-2-phenylpyrimidazolium p-toluenesulfonate An oil Tetramethylene-bis-2-phenylpyrimidazolium bromide 274- Comparable phosphorous-containing compounds, wherein the phosphorus atoms are separated by an alkylene group, as for example, tetramethylene-bis-triethyl-phosphonium bromide may be prepared in a comparable manner.

In addition to the compounds and methods referred to in the copending applications aforementioned, in certain instances the poly quaternary ammoniumsalts described in Charles F. H. Allen application, Serial No. 321,597, filed of even date, with that title, may be employed. Where, in the present application, we have referred to polyonium salts other than perchlorates, the salts may, if desired, be converted to the perchlorate, in accordance :with the method described in Charles F. H. Allen and Charles V. Wilson copending application Serial No. 321,599, filed of aaeazce even date, entitled "Surface active materials." As there described in detail, the perchlorates may be obtained by reacting a solution, as, for example, an alcoholic solution of the salt to be converted, with an alkali perchlorate, such as sodium perchlorate.

The quantity of polyonium salt which is most advantageously employed varies with the nature of the polyonium salt and with the nature of the emulsion. In most instances, a satisfactory concentration was found to be between about 20 mg. and 200 mg. of the polyonium salt per grammole of silver halide in the emulsion, although greater or smaller concentrations could be employed. We have found, however, that too large quantities of the polyonium salts are advantageously avoided, since excesses tend to produce fog in the emulsions. For our polyonium salts containing a bivalent organic radical having a chain of 1-6 members, we have found that the larger quantities, as for example, even 400 mg., of our polyonium salts could be employed without encountering excessive fog. In the instance of polyonium salts havinga bivalent organic radical containing a chain of 7 to 14 or more members, we have found that the lowerquantities, as for example, less than 200 mg., of the compound per mol of silver halide would be preferable.

The upper range of concentration for any particular one of our polyonium salts in any particular type of emulsion can be determined by employing a series of concentrations of the polyonium salt separately in several batches of the same emulsion, and determining the sensitivity of the several emulsions before and after incorporation of our polyonium salt or salts. This method of determining the optimum concentration may be carried out in any conventional manner. Briefly, the method we would employ would comprise coating the aforementioned emulsion in suitable thickness onto glass plates and then testing the resultant photographic plates in a wedge spectograph and a sensitcm eter, whereby the spectral sensitivity and speed of the emulsion on the plate may be determined.

When employing spectrally sensitized emulsions, the spectral sensitizers are advantageously employed in about their optimum concentration, which, for most purposes may be considered as lying between about 3 mg. and 20 mg. of spectral sensitizer per liter of emulsion containing about 0.25 mole of silver halide, although it is to be understood that these values are merely set forth for purposes of illustration and the concentrations above or below the aforementioned concentrations can be employed. With fine-grain emulsions (which includes many of the ordinarily employed silver chloride emulsions), the ratio of the sensitizing dye to the concentration of the silver halide inthe emulsion may advantageously be larger than in the coarser-grained emulsions, where smaller amounts of sensitizing dye will, in many instances, give satisfactory or optimum sensitization. The optimum concentration, as discussed herein, of a sensitizing dye, namely the concentration at which the apparently greater sensitivity occurs, can also be determined in any conventional manner known to those skilled in the art by measuring the sensitivity of a series of emulsions containing different concentrations of the sensitizing material. r

We wish to point out, however, that when our polyonium salts are incorporated into a spectral- 1y sensitized emulsion (as contrasted to an unsensitized emulsion), it is desirable that the serisitizing dye be compatible with our polyonium salt.

For this reason, as spectral sensltizers (sensitizing dyes), we would employ only those which are substantially non-acidic. As non-acidic sensitizing dyes, we include all the known neutral and basic sensitizing dyes, and it is to be understood that our invention is not restricted in this respect. Examples of some. of the non-acidic sensitizing dyes are the sensitizing cyanine dyes (see, for example, United States Patents 1,846,- 300; 1,846,301; 1,846,302; 1,846,303 and 1,846,304, each dated February 23; 1932', United States Patent 1,861,836, dated June 7, 1932, United States Patent 1,939,201, dated December 12, 1933, United States Patent 1,942,854, dated January 9, 1934, United States Patent 1,957,869, dated May 8, 1934, United States Patent 1,962,124, dated June 12, 1934, United States Patent 1,969,446, dated August 7, 1934, United States Patent 1,973,462,

dated September 11, 1934; United States Patent 1,990,507, dated February 12, 1935, United States Patent 2,094,580, dated October 5, 1937, United States Patent 2,112,140, dated March 22, 1938,

and French Patent 757,813, published January 5, 1934), the sensitizing merocyanine dyes (see United States Patent 2,078,233, dated April 27, 1937, United States Patent 2,089,729, dated August 10, 1937, United States Patent 2,153,169, dated April 4, 1939, and United States Patents 2,177,401; 2,177,402 and 2,177,403, dated October 24, 1939), the sensitizing hemicyanine dyes (see United States Patent 2,166,736, dated July 18, 1939) and the sensitizing hemioxonol dyes (see United States Patent 2,165,339, dated July 11, 1939, and French Patent 841,632, published May 24, 1939) It is consequently apparent from the foregoing that our polyonium salts may be incorporated in emulsions containing a large variety of difierent sensitizing dyes.

As already pointed out, our process is subject to considerable variation, particularly as respects the method of addition of our polyonium salts, the type of photographic material treated (spectrally sensitized or not) and the nature of the material and amounts added. However, in order that our invention will be further understood, we

describe examples of applying our invention to a photographic emulsion. It is to be understood that these examples are set forth primarily for the purposes of illustration and are not to be considered a restriction upon our invention.

EXAMPLE 7 To an emulsion optionally sensitized with at least one cyanine dye, as for example, 2,2'-diethyl-8-methyl thiocarbocyanine bromide, there is added thio-bis-ethylene pyridinium perchlorate. This substance may be prepared as follows:

A mixture of 4.5 parts of 5,5'-dichlorodiethylsulfide and 4.5 parts of pyridine is heated for 24 On cooling, a

In the instance of this example, the emulsion was not greatly changed in distribution of spectral sensitivity. However, the absolute value of sensitivity at any wavelength was increased by 25 to As the concentration of the polyonium salt was increased, its effect increased up to a certain point where there was also an undesirable increase in fog. Increase in concentration of the polyonium salt beyond this point did not improve the sensitivity.

EXAMPLE 8 In accordance with this example, compounds were prepared and added to the emulsion wherein the chain included a nitrogen atom. An example of such a compound is as follows:

These novel compounds may be prepared by reacting a diamide of the formula NHzCOYCONI-Iz with formaldehyde and, for example, hydrochloric acid.

By the term amide it is to be understood that we refer not only to simple amides, but to any derivatives obtainable by replacing one of the hydrogen atoms on the nitrogen atom by other groups, in particular, OH, NIH and also by varying the nature of the radical Y, which may be aliphatic, alkyl, aralkyl, or aromatic, and may or may not contain atoms other than carbon as a part of the chain.

A compound containing nitrogen in the chain in accordance with this example was incorpo rated into a silver halide emulsion as described in Example 7, and also found to increase the sensitivity 25-50%.

While in the foregoing examples, we have discussed the treatment of sensitized emulsions, it it to be understood that unsensitized emulsions may also be treated and the speed of such emulsions increased, for example, 50%,

Still further examples of photographic materials which have been treated in accordance with our invention are, for convenience, set forth in the following tables. It is to be kept in mind, as already pointed out, that our polyonium salts may be added before, with, or after the sensitizing dye or dyes or otherwise incorporated when preparing the photographic materials. In the instance of the perchlorate derivatives as we have discussed, we prefer to add such derivatives after the addition of the sensitizing dye. However, it

. is apparent that in the case of unsensitized emulsions, such preferance would not apply.

salts imparting the improvement therein.

In the following tables the material designated check, comprised an emulsion exactly com-- parable, similarly processed, etc., to the emulsion of our invention,-excepting that the check" did not embody our invention. In this Way we hav a basis of comparison,

the chainapparently the greater tendency to fog in too high concentrations. The heterocyclic nuclei aforementioned may be, for example, pyridine, piperid-ine, pyrazcles or pyriminazoles and" the like, 1 1

Our invention as illustrated by the examples in the tables under Table B concern the use of compounds having two non-cyclic quaternary nitrogens linked by means of an alkyl chain. Alkyl chains, as already discussed, maybe present, but preferably in the instance of the presence of small groups, as tri-ethyl, the chain will contain six or more carbon atoms, or-an aralkyl group attached to each nitrogen. Or the chain linking the two nitrogens may merely contain six or moreatoms, that is, one or more oxygen or sulfur atoms may replace carbon atoms in the.

chain, linking the two nitrogen atoms or in the chains attached to the two nitrogen atoms.

Our invention as illustrated by the examples polyonium salts containing two or more ternary sulfur atoms, each carrying an alkyl chain of six or more carbon atoms, or the equivalent. As already discussed, oxygen, nitrogen, or sulfur atoms may replace one or more of the carbon atoms in any of the alkyl chains.

From a consideration of the change in speed and a comparison of the other values observed, it will be noted that photographic materials treated by our invention compared with emulsions not embodying our invention but processed and otherwise handled in the same manner as products in accordance with our invention were substantially improved by our novel incorporation of the polyonium salts in the small amounts, as

already described in detail. Perchlorates have been favored in many instances, because they are readily crystallized and otherwise possess advantages. It will be noted, however, that p-toluenesulfonates and bromides have also been described in many of the examples. Hence. our invention is not to be unduly restricted in' this respect. As already discussed, the compounds may be added at any time, but our preferred operation comprises adding the polyonium salts to the emulsion shortly before coating and in rather small concentrations.

Our invention is useful for all types of optically sensitized emulsions, and even useful in unsensitized emulsions, especially unsensitized emulsions of relatively low iodide content.

It is, therefore, apparent from the foregoing that our invention is susceptible of some modification, hence wedo not wish-to be restricted,

excepting insofar as is-necessitated bythe prior art and the spirit of the appended'claims.

What we claim as our invention and desire to be secured by Letters Patent of 'the United States is:

1. A photographic silver halide emulsion containing a polyonium salt which contains an onium salt group, selected from the groupcon another onium salt group, selected from the group consisting. of quaternary ammonium, quaternary phosphonium and ternary sulfonium salt groups.

2. A photographic gelatino-silver-halide emulsion containing a polyonium salt which contains an onium salt group, selected from the group consisting of quaternary ammonium, quaternary phosphomum and ternary sulfonium salt groups, linked through its onium atom, by at least one bivalent organic radical, to the onium atom of another onium salt group, selected from the group consisting of quaternary ammonium, quaternary 'phosphonium and ternary ,sulfonium salt groups.

3. A photographic-silver-halide emulsion containing aquat'ernary ammonium salt which contains a quaternary ammonium salt group linked through its ammonium atom, by at least one bivalent organic radical, to the ammonium atom of another quaternary ammonium salt group.

4. A photographic gelatino silver halide emulsion containing a polyonium salt of the following general formula:

n" x X n" wherein R, R and R" represent alcohol radicals, X represents an acid radical and Z represents a bivalent organic radical.

5. A photographic gelatino silver halide emulsion containing a polyonium salt of the following general formula:

- linked through its onium atom by at least one bivalent organic, radical to the onium atom of another oniumsalt group selected from the group consisting of quaternary ammonium, quaternary phosphonium and ternary sulfonium salt groups. 7. A photographic gelatino silver halide developing-out emulsion containing a polyonium salt which contains an onium salt group selected from the group consisting of quaternary ammonium, quaternary phosphonium and ternary sulfonium salt groups, linked through its onium atom by at least one bivalent organic radical to the onium atom of another onium salt group selected from the group consisting of quaternary ammonium, quaternary phosphonium and ternary sulfonium salt groups.

8-. A photographic silver halide developin -out emulsion containing a quaternary ammonium salt which contains a quaternary ammonium salt group linked through its ammonium atom -byat least one bivalent organic'radical to the ammonium atom of another quaternary ammonium salt group.

9. Aphotographic gelatino silverhalide devel oping-out emulsion containing aquaternary ammonium salt which contains a quaternary ammonium salt group linked through its ammonium atom by at least one bivalent organic radical to the ammonium atom of another quaternary ammonium salt group.

10. A photographic gelatino silver halide developing-out emulsion containing a polyonium salt of the following general formula:

oping-out emulsion containing a polyonium salt of the following general formula: 4

wherein Q represents the non-metallic atoms necessary to complete an organic heterocyclic nuclei, X represents'an acid radical and Z represents a bivalent organic radical.

12. A photographic gelatino silver halide developing-out emulsion containing, in a concentration of not more than 400 milligrams per grammole of the silver halide in the emulsion, a polyonium salt which contains an onium salt group selected from the group consisting of quaternary ammonium, quaternary phosphonium, and ternary sulfonium salt groups, linked through its onium atom by a bivalent organic radical consisting of a chain' of from 1 to 6' members, to the onium atom of another onium salt group selected from the group consisting of quaternary ammonium, quaternary phosphonium and ternary sulfonium salt groups.

13. A photographic gelatino silver halide developing-out emulsion containing, in a concen- ,a polyonium salt of the following general formula: I

/Q Q\. b=N-ZN=d 1': 1':

wherein Q represents the non-metallic atoms necessary to complete an organic heterocyclic nucleus selected from the group consisting oi pyridine, pyrazole and pyriminazole nuclei, X

represents an acid radical and Z represents a bivalent organic radical consisting of from 7 to 14 members. I

16. A photographic gelatino silver halide developing-out emulsion containing, ina concentration equal to not more than'400 milligrams per gram-mole of the silver halidein the emulsion, a polyonium salt of the following general formula: I

' valent organic radical consisting of from 1 to 6 tration equal to not more than 200 milligrams per gram-mole of silver halide in the emulsion, a polyonium salt whichcontained an onium salt group selected from the group consisting of quaternary ammonium, quaternary phosphonium and ternary sulfonium salt groups, linked through its onium atom by a bivalent organic radical consisting of a chain of from 1 to 6 members, to the onium atom of another onium salt group selected from the group consisting of quaternary ammonium, quaternary phosphonium and ternary sulfonium salt groups.

14. A photographic gelatino silver halide developing-out emulsion containing, in a concentration equal to not'more than about 400 milligrams per gram-mole of the silver halide in the emulsion, a polyonium salt of the following general formula:

wherein Q represents the non-metallic atoms necessary to complete an organic heterocyclic nucleus selected from the group consisting of pyridine, pyrazole and pyriminazole nuclei, X represents anacid. radical and Z represents a bivalent organic radical consisting of a chain of from 1 to 6 members.

15. A photographic gelatino silverhalide developing-out emulsion containing, in a concentration of not more than 200 milligrams per gram-mole of the silver halide in the emulsion,

members. l

17. A photographic gelatino silver halide developing-out emulsion containing, in a concentration of not more than 200 milligrams per gram-mole of the 'silver halide in the emulsion, a polyonium salt of the following general formula:

wherein Q represents the non-metallic atoms necessary to complete a pyridine nucleus, X represents an acid radical and Z represents a bivalent organic radical consisting of from 7 to 14 members.

18. A photographic gelatino-silver-halide developing-out emulsion containing a nonacidic sensitizing dye and containing a polyonium salt which contains an onium salt group selected from the group consisting of quaternary ammonium, quaternary phosphonium and ternary sulfonium salt groups, linked through its onium atom by at least one bivalent organic radical to the onium atom of another onium salt group selected from the group consisting of -quaternary ammonium, quaternary phosphonium and ternary sulfonium salt groups. I

19. A photographic gelatino-silver-halide developing-out emulsion containing a non-acidic sensitizing dye and containing, in a concentration equal to not more than 400 milligrams per equal to not more than 200 milligrams per grammole of the silver halide in the emulsion, a. polyonium salt which contains an onium salt group selected from the group consisting of quaternary ammonium, quaternary phosphonium and ternary sulfonium salt groups, linked through its onium atom by a bivalent organic radical consisting of a chain of from 7 to 14 members, to the onium atom of another onium salt group selected from the group consisting of quaternary ammonium, quaternary phosphoni- 5 um and ternary sulfonium salt groups.

BURT H. CARROLL. CHARLES .F. H. AILEN.

CERTIFICATE OF CQRREC'IION.

Patent No. 2,288,226. June 50, 19!;2.

' BURT H. CARROLL, ET AL.

It is hereby certified that error appears -in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, lines 18 to 21, for that portion of Formula III reading page 5, first column, line 56, for "optionally" read -optically-; page 6, lines l0, l5 and 111., Table A, fourth column thereof, for "2.820", "1.550" and "1.14.10" read --2, 2o--, --1, 50--, and --1,L;1o-- respectively, and that the said Letters Patent should be read with this correction therein'that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 15th day of September, A. D. l9lp2.

Henr3 Van Arsdale, (Seal) I Acting Commissioner of Patents.