Proceedings of the Photographical Section. 1085 



April 5, 1870. 



Mr. Henry T. ANTnoinr in the chair ; Mr. O. G. MiisoN, Secretaiy. 



Mr. Ilallenbeck gave the following formula for printing in dull 

 weather, and stated that by it he had produced very good prints, 

 which could not at the time have been made by any of the ordinary 

 processes : 



Float plain paper three minutes on water 20 oz., bichloride of 

 mercury five grains. Hang up until thoroughly dry, then float for 

 one minute on a thirty-iive grain solution of nitrate of silver, and after 

 drying and exposure under negative the image is developed with 

 water ten ounces, proto-sulphate of iron 350 grains, glacial acetic acid 

 four ounces. As this paper is very sensitive it should be kept pro- 

 tected from actinic light after it has been sensitized, until the image 

 is fully developed. 



Mr, Chapman deemed the development of the image with iron a3 

 a very important feature, as many experimenters had not been able 

 to preserve clearness and fine detail, with an iron developer on paper. 



The Chairman thought that the success of the process was in a 

 great measure due to the organic matter used in sizing the paper 

 while in the process of manufacturing, and the varying nature and 

 quality of which might explain the great variety of results obtained 

 in the developing process on such light and porous material. 



Mr. Dimmers stated that a very similar process had been published 

 some years ago, and that one of bis friends had worked it successfully 

 in solar printing. 



After some further discussion upon the process by several members, 

 Professor Tillman moved that a committee consisting of Messrs. 

 Hallenbeck, Chapman and Dimmei'S be appointed to experiment with 

 the process given by Mr. Hallenbeck, and report at a future meeting 

 of the Section. The motion was unanimously carried. 



Mr. Chapman exhibited a four-inch negative of the sun, and made 

 remarks upon its characteristic features, some of the larger spots, 

 with their surroundings, faculse, were plainly shown in the image. 



Mr. jSTewton exhibited samples of albumenized paper, which had 

 been sensitized on the 31st day of December last, and had not 

 changed ; also a print made on the same day and toned on the first 

 day of April ; also another print on the same paper, made and toned 

 on the last named day, all of which very clearly demonstrated that 



