hydrofluate

‘Harvest Scene’ in the exhibition, being from an albumen negative lent me by Mr. Ross, the well-known Edinburgh photographer, is an example, the salt of the sesquioxide of uranium being in this case the hydrofluate, and the time of exposure from the strength of the albumen negative fully an hour of good sunshine.

Photographic Reproduction Processes Peter C. Duchochois

*** I have tried the hyposulphite of gold on some of the silver-developed prints prepared with the hydrofluate of the uranic oxide and fixed with ammonia, which had an exceedingly unpleasant raw-red color, a very agreeable gray was at once obtained.

Photographic Reproduction Processes Peter C. Duchochois

For instance, a collodion negative with the hydrofluate paper producing a very good print in half an hour of unsteady sun, while with a paper prepared with the tartaric acid solution of the oxide, it gave an equally good impression in less than five minutes of the same intermitting sunshine, indicating thus a difference of sensitiveness of six to one in favor of the tartrate.”

Photographic Reproduction Processes Peter C. Duchochois