Royal Irish Academy. 389 



the sole constituents of the substance are phosphoric acid, peroxide 

 of uranium, oxide of copper, lime and water, a known weight was 

 dissolved in hydrochloric acid, and copper was precipitated as sul- 

 phuret by transmitting sulphuretted hydrogen gas through the solu- 

 tion. The precipitated sulphuret, when filtered and washed, was 

 digested in nitric acid, and from the solution thus obtained, oxide of 

 copper was precipitated by potash, washed, ignited and weighed. 



(2.) The solution, separated by filtration from the sulphuret of 

 copper, was next evaporated to dryness and mixed with a little con- 

 centrated sulphuric acid to convert phosphate of lime into sulphate, 

 the mixture was diluted with alcohol, in which sulphate of lime is 

 quite insoluble, and filtered. The sulphate of lime was washed with 

 alcohol, dried, ignited and weighed. 



(3.) The filtered alcoholic solution, containing phosphate of ura- 

 nium dissolved in the excess of sulphuric acid, was evaporated to 

 dryness, the residue digested in nitric acid, and phosphate of ura- 

 nium precipitated from the acid solution by ammonia. This, when 

 washed and dried, was gently ignited and weighed. 



(4.) The water contained in the substance was determined by ob- 

 serving what loss in weight it sustained when calcined at a dull red 

 heat ; and 



(5.) The remaining ingredient, the phosphoric acid in combina- 

 tion with oxide of copper and lime, was considered as the deficiency 

 on the weight of the original substance. 



" Some additional Observations on the Red Oxalate of Chro- 

 mium and Potash," by Robert Warington, Esq. This paper has 

 been inserted in the present volume, p. 201. 



ROYAL IRISH ACADEMY. 



[Continued from p. 233.] 



May 24, 1841 (Continued).— The following Note "On the Force 



of aqueous Vapour within the Range of atmospheric Temperature," 



was read by James Apjohn, M.D., M.R.I. A., Professor of Chemistry 



in the Royal College of Surgeons. 



Having had it in contemplation some time since to investigate by 

 means of an indirect, but I believe a very accurate process, the ca- 

 loric of elasticity of the vapours of several liquids, I found myself 

 stopped on the threshold of the inquiry by a want of knowledge of 

 the tension of such vapours at different temperatures ; for, with the 

 exception of the vapours of water, alcohol, aether, and oil of turpen- 

 tine, the tension of no others had been made the subject of experi- 

 ment ; and even in the case of the fluids just named, the results re- 

 corded in the books appeared to me very far from being of such a 

 nature as to preclude the necessity of further research. 



The method which I intended to employ, in order to arrive at the 

 latent heats of vapours, not requiring a knowledge of their tensions 

 beyond the range of atmospheric temperature, it occurred to me, that 

 the necessary data for the solution of the preliminary problem might 

 be obtained with facility, and, at the same time, with much precision, 

 in the following manner : — 



