486 Rev.W. V.Harcourt on Lord Brougham's statement* 



In these views the new discovery of the various permanence 

 and condensability of the gases has a conspicuous place : " On 

 the same difference of size," he says, " may depend the more 

 or less permanency of aerial substances in their state of rare- 

 faction." " This may be the reason why the small particles of 

 vapours come easily together and are reduced back into water, 

 unless the heat which keeps them in agitation be so great as 

 to dissipate them as fast as they come together, but the grosser 

 particles of exhalations raised by fermentation keep their 

 aerial form more obstinately, because the aether within is 

 rarer. Nor does the size only, but the density, of the parti- 

 cles also conduce to the permanency of aerial substances: for 

 the excess of density of the aether 'without such particles above 

 that of the aether l withi?i them is still greater : which has made 

 me sometimes think that the true permanent air may be of a 

 metallic original, the particles of no substances being more 

 dense than those of metals. This I think is also favoured by 

 experience: for I remember I once read in the Philosophical 

 Transactions how M. Huygens at Paris found, that the air 

 made by dissolving salt of tartar would in two or three days' 

 time condense and fall down again ; but the air made by dis- 

 solving a metal continued without condensing or relenting in 

 the least. If you consider then how by the continual fermen- 

 tations made in the bowels of the earth there are aerial sub- 

 stances raised out of all kinds of bodies, all which together 

 make the atmosphere, you will not perhaps think it absurd, 

 that the most permanent part of the atmosphere, which is the 

 true air, should be constituted of these; especially since they 

 are the heaviest of all others, and so must subside to the lower 

 parts of the atmosphere and float upon the surface of the earth, 

 and buoy up the lighter exhalations and vapours to float in 

 greatest plenty above them. Thus I say it ought to be with 

 the metallic exhalations raised in the bowels of the earth by 

 the action of acid menstruums ; and thus it is with the true 

 permanent air." 



These extracts show that Newton considered the hydrogen 

 gas which Boyle had obtained from iron, and the nitrous gas 

 which Huygens had obtained from copper, as consisting of 

 the ultimate particles of the iron and copper themselves, 

 brought into a state of aerial elasticity ; and further, that ap- 

 prehending his aetherial hypothesis to be thus strengthened 

 by experimental facts, he proceeded to generalise so boldly, as 

 to conclude that the whole body of the inferior atmosphere 

 may be constituted of various metallic substances, and that 

 the power and persistence of elastic force in different kinds 

 of air may be proportionate to the size and density of their 

 chemical elements. 



