340 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 39 



Photographic films and plates keep as long as they are stored in 

 an airtight canister and their seals are unbroken. Once they are 

 opened they deteriorate rapidly, and if not developed soon after ex- 

 posure the emulsion, celluloid, and paper backing become a limp, 

 sticky mass. Except near the boundary where the springs are clear 

 and cold, it is difficult to obtain water clean enough and at a tempera- 

 ture below 75° to 80° F. for development. At this temperature the 

 process is difficult to control, and even an acid hardening bath will 

 not eliminate reticulation and frilling. It is also almost impossible 

 to wash negatives adequately and quite impossible to dry them. 

 Finally, when packed away under double seals they form an excellent 

 medium for the growth of fungus. 



