US722238A

US722238A - Photographic emulsion and process of making same.

Info

Publication number: US722238A
Application number: US7879301A
Authority: US
Inventors: Hans Luettke
Original assignee: Individual
Current assignee: Individual
Priority date: 1901-10-16
Filing date: 1901-10-16
Publication date: 1903-03-10
Anticipated expiration: 1920-03-10

Description

HANS LUTTKE, OF HAMBURG, GERMANY.

PHOTOGRAPHIC EMULSION AND PROCESS OF MAKING SAME.

SPEUIFICATION formingpart of Letters Patent N 0. 722,238, dated March 10, 1993.

Application filed October 16,1901. Serial No. 78,793. (No specimens.)

T0 alZluhoml it may concern:

Be it known that I, HANS LUTTKE, a citizen of Prussia, and a resident of Hamburg, Germany, have invented certain new and useful Improvements in Photographic Emulsions and Processes of Making the Same, of which the following is a specification.

My invention relates to the manufacture of light-sensitive emulsions such as are used for coating printing-out paper. Such papers as a rule are coated with an emulsion containing silver chlorid, and it is Well known that the tint or color obtained by simply fixing the print is unsatisfactory and that for this reason a separate operation called toning is generally resorted to for the purpose of giving the image an agreeable tone. The toning solutions generally contain gold salts. Attempts have been made to incorporate gold salts with the emulsion, so that the prints might be fixed at once without a separate toning operation. These attempts, however, have so far failed to accomplish a thoroughly satisfactory result.

I have made extensive experiments, and as a result of this investigation I have come to the conviction that the reason of the failure experienced so far is the employment of chlorids, either of gold alone or gold in connection with alkalies. When such salts are used, the chlorin combines with the silver, and a gold compound is formed and precipitated which is not available for toning purposes. I have found that gold compounds containing no chlorin are required to avoid the defects hitherto observed and that the following substances are particularly well suited for the intended purpose: auryl sulfate, (Au OH.HSO auri nitrate nitric acid, Au (N0 +HNO +3H O, as well as the alkali double salts of these compounds, and principally the double salt of lithium. When employing emulsions containing these gold salts, an image is produced which consists not only of reduced silver, but also of reduced gold. The toning process therefore takes place simultaneously with the printing, and subsequent toning such as now practiced is dispensed with.

I find that the best results are obtained if the emulsion contains a proportion of silver chlorid equal to from thirty to fifty per cent. of the entire quantity of silver. I find that the reduced silver which has been produced by exposing to light mixtures containing silver chlorid, silver nitrate, and silver citrate has in a very high degree the property of reducing gold.

As an example of my invention I will give the following receipt for an emulsion: (A) Celloidin collodion, four per cent, six hundred and twenty cubic centimeters; ether, 0.720, one hundred cubic centimeters; alcohol, ninety-six per cent, thirty cubic centimeters. (B) Silver nitrate, twenty-five grams; water, twenty-five cubic centimeters; alcohol, one hundred and twenty cubic centimeters; gold and lithium nitrate, 1.4 grams; auryl sulfate, 0.9 grams; lithium auryl sulfate, 1.3 grams. (0) Calcium chlorid, (anhydrous,) three grams, or lithium chlorid, (anhydrous,) three grams. (D) Citric acid, five grams; alcohol, thirty cubic centimeters.

It will be understood that the collodion is used as a binder and that instead of this I may employequivalent substances, as gelatin, albumen, and starch.

I may employ gold nitrates or sulfates, as hereinbefore described, as equivalents, and while in the claims I refer to the sulfates only I desire it to be understood that the employment of a gold nitrate is to be considered covered as an equivalent.

Having described my invention, What I claim, and desire to secure by Letters Patent, 1s

1. The process of producing photographic emulsions, which consists in adding a gold sulfate to an argentic emulsion.

2. The process of producing photographic emulsions, which consists in adding a gold sulfate to an argentic emulsion and chemically binding to chlorin from thirty to fifty per cent. of the total amount of silver contained in the emulsion.

3. An argentic photographic emulsion, said emulsion containing a gold sulfate.

4. An argentic photographic emulsion, said.

emulsion containing a gold sulfate and having from thirty to fifty per cent. of the entire silver contents chemically combined with chlorin.

HANS LUTTKE. Witnesses:

E. H. L. MUMMENHOFF, OTTO W. IIELLMRIOH.