and their Connexion with Volcanos. ^X 



cubic inches) of hydrogen weighs only 36.6 grains, and as 

 a French lb. contains 7561 English troy grains, every lb. 

 of hydrogen would occupy a volume of about 20 cubic feet. 

 Hence 487,955,0561b. of hydrogen would occupy 9,759,101,120 

 cubic feet; or, according to the same calculation, 14 square 

 leagues covered to 4 inches, or 1 inch covered to 5Q inches. 

 For, as 663,000,000 : 4 : : 9,760,000,000 : BQ. 



But it will be directly perceived, that all this calculation has 

 reference to a different hypothesis from the one I have adopted; 

 for, if we only allow that atmospheric air finds admission to the 

 immediate seat of the action, it will follow that, at this high 

 temperature, its oxygen will enter into union with any hydrogen 

 that may have been evolved, so that a comparatively small quan- 

 tity of water will serve the same office in this great natural la- 

 boratory, which nitre is known to fulfil in our oil of vitriol ma- 

 nufactories; the same portion of this fluid serving over and over 

 again as the carrier of oxygen to the metallic matter which is 

 capable of decomposing it, just as the nitrous gas generated by 

 the nitre furnishes oxygen to the sulphurous acid, owing to its 

 previous conversion into nitrous acid vapour. 



Even setting aside these considerations, the validity of which 

 is dependent upon the admission of this particular theory, it 

 must be acknowledged as a matter of fact, that sulphurous acid 

 and sulphuretted hydrogen are both common products of volcanic 

 action ; now it is the known property of these two gases to de- 

 compose each other when brought into contact, and if moist*, to 

 generate water by the union of the oxygen of the former with the 

 hydrogen of the latter. In both these ways, probably, it hap- 

 pens, that, although water is the prime mover in the chain of ef- 

 fects, atmospheric air is the principal supporter of the combus- 

 tion so excited ; and consequently, that, in conformity with the 

 other arrangements of nature, the relations between the sea and 

 land remain unaltered by the process, however often it may be 

 repeated, the whole of the water at first decomposed being sooner 

 or later returned to its original receptacle. 



• When dry, a solid body is produced by their union, called Hydrosulphu- 

 rous Acid, but this again is resolved into sulphur and water, so soon as any 

 moisture is present. 



