GELATIN PROCESS

the photographic proce which replaced the old wet-plate proce , and which consists in the use of a plate or film prepared by coating a sheet of gla or celluloid with a sensitized film of gelatin emulsion. The exact methods by which the various grades of gelatin emulsions ane repels are kept as carefully guard secrets by the different manufacturers, but the basis on which all the proce es depend may be outlined as follows. The gelatin is soaked in water containing a small quantity of pota ium bromide. A solution of silver nitrate is then prepared by di olving in water, and adding ammonia in exce , so that the precipitate first formed is di olved. The two solutions are then heated to a tem ture of 35° C, and when the gelatin is perfectly liquid, the silver salt is added, gradually, with constant stirring. The emulsion is kept at the above tempera-| ture for 30 to 40 minutes, and is then}the poured out and allowed to set. The] Jelly is next thoroughly washed to] remove exce silver, and is then ready for coating the plates. A ea inet oa ical arrangements are used for obtaining an even coat, after which the plates are dried. The operations must, of course, be carried out in ruby light. The proce depends upon the fact that bromides|_ react with silver salts, producing in-| soluble silver bromide, which is sensitive to light. The various ‘speeds’ of film are obtained by controlling the finene of grain of the precipitate, and by various secret proce es. rovinee, Netherlands, 8.E, of Zuider Zee; surface more hilly than most of Dutch provinces; traversed by. Waal, Rhine, Y el, Maas; soil very ‘fertile along river banks. Chief crops—cereals, flax, tobacco; cattle-rearing, brick-making, paper and cotton industries carried on; ls capital, » ’ 1920, Arnheim. 727.686.” Area, 1965 s @-| so Coudtsht ne ta ane EN THS pce Duchy, 1338 “tee the Empire: thrived in commerce; seized by Maximilian of Austria, 1483; absorbed in Hapsburg Netherlands, 1543; north (present Dutch province) seceded, south adhered to Spain, 1579; divided between Holland and Pru ia, 1814, town, Germany, Pru . Rhine province;| formerly residence of Dukes of Gelder-| land. Pop. 6,000.