HYDROGEN AS A GAS AND AS A METAL. 



By Dr. J. E.mersox Eeyxolds. 



Notes of a lecture delivered in the tlieater of the Eoijal Dublin Society. 



When the programme of this course of lectures was published, it 

 became evident that the subject of the present one was, by a singular co- 

 incidence, closely connected with that of two of the earlier lectures of 

 the series. I refer to the discourse of Mr. Stoney on " Meteoric Show- 

 ers," and of Professor Ball on " Xebulfe." In the latter lecture, we 

 learned that.manj' of the thin mists observable in the heavens are not 

 star clusters, as they were long supposed to be, but are enormous masses 

 of gaseous matter in a state of intense ignition. The examination of 

 the light emitted by these nebulte enables us to state with certainty that 

 at least one elementary bodj' well known upon this earth is present 

 in all of them as a principal constituent, and that element is one ^vhich 

 chemists call hydrogen. In Mr. Stoney's lecture on " Meteoric Showers," 

 he pointed out that some of these strange visitors to our globe, the me- 

 teoric stones, are found to contain pent up within them a certain gas, 

 which gas has been shown by analysis to be hydrogen. We find, then, 

 this hydrogen in enormous quantities throughout space, and at so great 

 a distance from our planet that the human mind is unable to appreciate 

 the interval which separates us from even the nearest of those mighty 

 gaseous oceans. Again, we find this hydrogen carried to our planet by 

 those strange wanderers of interstellar space, the meteors. And, tinally, 

 we have it on this earth, not in the free state, it is true, but as an essen- 

 tial constituent of one of the most imjiortant components of this globe, 

 viz, water. 



Our object in this lecture, then, is to study this remarkable element, 

 hydrogen, as we meet with it here, to determine some of its chief prop- 

 erties, and to ascertain its nature. 



It has been already said that our chief storehouse of hydrogen on 

 this earth is water, but we find it in many other well-known bodies; for 

 instance, in the dreaded " tire-damp" of our coal mines we have the hy- 

 drogen combined with another element, carbon. Again, common coal- 

 gas contains a large proportion of hydrogen ; and I have only to men- 

 tion that this same body is an essential constituent of the bread we eat, 

 the sugar we mix with our tea, the clothes we wear, of our tlesh and 

 blood too, in order to show that this is one of the most widely diffused 

 of that class of bodies known to chemists as elementary Ibrms of mat- 

 ter. But though we find hydrogen in all the substances mentioned just 



