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On Phosphuretted Hydrogen. By Thomas Graham, Esq. 

 F. R. S. Ed., Lecturer on Chemistry in the Andersonian In- 

 stitution, and V. P. Phil. Soc. Glasgow. 



{Bead \st December 1834.) 



Few substances have been made the subject of experimental 

 inquiry more frequently than the compounds of phosphorus and 

 hydrogen, and no subject is so remarkable for the various and 

 conflicting results which it has presented to chemists of the 

 greatest acuteness and practical skill. The obscurity which long 

 hung over the subject has been dispelled, however, in a great 

 measure, by the recent investigations of Henry Rose of Berlin. 

 Although baffled in his early researches, that philosopher return- 

 ed again and again to the subject, and at last succeeded in de- 

 termining the chemical functions and true constitution of phos- 

 phuretted hydrogen. He has shewn it to be analogous to am- 

 monia in chemical character and composition. But hitherto two 

 compounds of phosphorus and hydrogen had generally been ad- 

 mitted to exist, which were believed to differ in composition, as 

 they do in properties, one being spontaneously inflammable in 

 atmospheric air, and the other not so. Rose establishes beyond 

 all doubt that these gases are essentially of the same composition, 

 and of the same specific gravity ; and, indeed, that they are mu- 

 tually convertible, each into the other, without any addition or 

 subtraction of matter that could be perceived. In explanation 

 of their possessing different properties, under the same composi- 

 tion, allusion is made by Rose to Isomerism, or the doctrine that 

 two bodies may exist identical in composition, but differing in 

 properties. Certainly the existence of two gases, constituted 



