Becord, xxiii 



replaced by ten drops of saturated potassium bichromate so- 

 lution, and four drops of common C. P. nitric acid, to three 

 ounces ( 90 cc. ) of water. There is reason to believe that 

 any camera exposure which was intended to be correct may 

 be developed as a positive in the light by such methods. It 

 is certain that it may be handled as a negative in the dark- 

 room. 



Professor Nipher stated that if either a negative or a posi- 

 tive had been started and had resulted in a failure, due to 

 improper treatment, the picture with the fog on the plate 

 might be chemically destroyed by chromic acid, and the pic- 

 ture might be redeveloped in either case either as a negative 

 in the dark- room or as a positive in the light. 



It was also stated that one plate had been developed as a 

 superb negative at a distance of a meter from a 300 candle 

 lamp. This case was very remarkable, because, on account 

 of an accident in the treatment, a failure or a poor positive 

 had been expected. Several repetitions of this treatment had 

 failed to yield this result again. 



It is frequently observed that with a strong pyrocatechin 

 developer the picture will start as a negative in the light, and 

 will reach a fair degree of excellence, and then reverse. This 

 is all in the nature of an oscillation such as is known in elec- 

 tric discharges. The phenomenon is not observed in a weaker 

 or in a more slowly acting bath. The anomalous case before 

 referred to could hardly be accounted for in this way, be- 

 cause the picture developed very slowly in a normal hydro- 

 chinon bath, and grew steadily better until it was sharply 

 defined on the back of the film. This case is still being 

 examined. 



Mr. George A. Held and Dr. George Homan, of St. Louis, 

 were elected to active membership. 



One person was proposed for active membership. 



March 4, 1901. 



President Engler in the chair, fourteen persons present. 



The Council reported that at their request Professor T. H. 

 Macbride and Mr. W. L. Sachtleben, who had not qualified, 

 had been dropped from the list of members. 



