145 



lm. W., September 23d, A. M. Dip 72° 7'.1. Baltimore, Mary- 

 land, lat. 39° 17' N-, long. 5h. 7m. W., September 25th, A. M. Dip 

 71° 50'.3. Washington City, lat. 38° 53' N., long. 5h. 8m. W., 

 September 25th, P. M. Dip 71° 21 '.4. Pittsburgh, Pennsylvania, 

 lat. 40° 32' N., long. 5h. 20m. W., September 30th, A. M. Dip 72° 

 38'.9. Beaver, Pennsylvania, lat. 40° 44' N., long. 5h. 22m. W., 

 October 1st, A. M. Dip 72° 40'.3. Hudson, Ohio, lat. 41° 15' N., 

 long. 5h. 26m. W., October 7th, P. M. Dip (observations repeated) 

 72° 45 '.9. 



These observations were made with the instrument by Gambey, 

 with which the results contained in Prof. Loomis's former paper were 

 obtained. The series is the most extensive yet made in the United 

 States, with which the Committee are acquainted. 



The Committee, consisting of Dr. Hare, Dr. Bache, and Mr. 

 Booth, on a paper entitled "On a new compound of deuto- 

 chloride of platinum, nitric oxide, and hydrochloric acid ; by 

 Henry D. Rogers, Professor of Geology in the University of 

 Pennsylvania, and Martin H. Boye, Graduate of the Univer- 

 sity of Copenhagen," reported in favour of publication in the 

 Transactions of the Society. The publication was ordered 

 accordingly. 



This substance is procured by dissolving platinum in an excess of 

 nitromuriatic acid, and evaporating nearly to dryness ; after which it 

 is treated with aqua regia, freshly prepared, from concentrated hy- 

 drochloric and nitric acids. A little water is afterwards added, drop 

 by drop, just sufficient to keep the chloride of platinum dissolved, 

 when the compound will remain in the form of a gamboge yellow 

 powder. It is then separated by decanting and filtering, and pressed 

 between the folds of bibulous paper, and dried in vacuo over sulphuric 

 acid. 



The precipitate is a yellow, minutely crystalline powder, which ab- 

 sorbs water with great avidity. It may be preserved, without decom- 

 position, in dry air, or in vacuo. It is decomposed by water, alcohol, 

 &c, with extrication of nitric oxide, chloride of platinum remaining in 

 solution. A concentrated solution of chloride of platinum has, how- 

 ever, no action on it. Heated in an atmosphere of hydrogen, it gives 

 off a large amount of chloride of ammonium, leaving a residuum of 

 metallic platinum. 



Analysis. — The salt analysed, was prepared and kept in the man- 



B 



