1094 Transactions of the American Institute. 



Prof. P. Yanderweyde exhibited a series of card-size photographic 

 views from Holland. 



The section then adjourned to the first Tuesday in June. 



June 2, 1868. 



Joseph Dixok Esq., in the chair. Oscar G. Mason, Secretary. 



Mr. C. Wager Hull presented several numbers of the " Mittheil- 

 ungen fur Photographic," published at Berlin, Prussia, which he had 

 received for the section. 



Professor S. D. Tillman read from Humphreys's Journal of Photo- 

 graphy^ an account of experiments recently made by Mr. McLochlan, 

 of England, who claims to have discovered a method of obviating 

 many of the perplexities appertaining to photography, by so modi- 

 fying the negative, sensitizing both as to admit of its being 

 worked in an alkaline condition, rendering it more sensitive, and less 

 liable to derangement by the absorption or solution of organic matter. 

 The article called out considerable discussion, which was warmly 

 entered into by several members. On motion of Mr. H. J. ITewton, 

 the chair appointed a committee consisting of Messrs. Newton, Mason, 

 Chapman, and Yanderweyde, to experiment upon the theory 

 advanced by Mr. McLochlan, and report at a future meeting of the 

 section. 



Prof. Yanderweyde translated from the " Mittheilungen fur 

 Photographic," an article upon " phosphorescent photography." The 

 image was produced upon an albumen substratum, by the use of sul- 

 phate of baryta and gum tragacanth finely pulverized. The image 

 is rendered more permanent by a thin coat of parafline. 



Mr. D. Chapman exliibited a print made from an instantaneous 

 negative, developed with the ordinary iron developer, after which it 

 was washed and then redeveloped with the following mixture : Water, 

 one ounce ; carbonate of ammonia, ten grains ; pyrogalic acid, eighty- 

 five grains ; alcohol, one ounce ; and two minims of a five grain solu- 

 tion of bromide of potassium. 



Mr. H. J. Newton said he had produced good negatives with an 

 exposure of six seconds, by using an alkaline developer as follows : 

 Three ounces of water at 150 degrees F. ; a twenty grain solution of 

 carbonate of ammonia, one drachm ; a twenty-five grain solution of 

 bromide of potassium, one-fourth drachm, a fifty grain solution 



