on the Atomic Theory. 127 



pressure of 30 inches of mercury, and at the temperature of 60°, 

 is 138.7551 cubic inches *." 



There is an astounding fatuity in this passage. The flask loses 

 3 grains in weight; of this loss, he calculates that 0.2225 is due 

 to moisture vaporized in the hydrogen. Hence, 3 — 0.2225 

 = 2.7775 is the weight of the dry hydrogen, by his own shew- 

 ing. The fractional quantity 0.059 is merely the moisture, which, 

 by his account, escaped the hygrometric action of the muriate of 

 lime, which quantity + that in the muriate of lime = 0.2225 falls 

 to be deducted from the loss of weight in the flask = 3 grains. 4 

 And what is the drift of this novel experiment ? Do its results 

 shew the weight of a given bulk of hydrogen, in a definite state of 

 moisture or dryness ? Certainly not. For, though his purpose 

 was to determine experimentally the proportion of dry air and 

 moisture in a known volume of the moist gas, he is obliged to 

 have recourse to calculation, to learn that proportion. But as he 

 does not know the temperature of the effluent hydrogen, he wants 

 the essential datum of that calculation. And supposing that by a 

 wiser disposition of the experiment, he had known this datum, 

 still his result would have been wrong, because the specific gra- 

 vity of aqueous vapour is very different from what he assumes it 

 to be in his formula. The confusion of thought, discovered by the 

 Doctor on the present occasion, can only be accounted for on the 

 supposition, that his head got turned in planting, as he fondly 

 fancied, " the key-stone" of the grand atomic arch. We do not 

 consider the experiment susceptible of remarkable precision in 

 the best hands ; but at any rate it might be made a rational, if it 

 cannot be made a delicate one, by causing the disengaged gas to 

 traverse a convoluted glass tube, surrounded by melting ice. The 

 hydrogen would then escape in a definite hygrometric state, and 

 its weight would be exactly known from the loss of weight suf- 

 fered by the apparatus. 



He concludes as follows: — "Thus it appears that 138.7551 

 cubic inches of dry hydrogen gas (bar. 30 inches, therm. 60°) 

 weigh 2.941 grains; consequently 100 cubic inches must weigh 

 2.119 grains. " 



On the contrary, the weight of that bulk of his dry hydrogen is, 

 by his own statement, 2.778 grains, and therefore the weight of 

 100 cubic inches is 2.77S divided by 1.387551 = 2.002. 



" But we have seen in the last section that 100 cubic inches of 

 oxygen gas weigh 33.915 grains ; now 



2.119 : 33.915 :: 1 - 16.005. 

 " This approaches so nearly the ratio of 1 : 16, that it leaves 

 no doubt that the specific gravity of oxygen gas is exactly 16 

 times greater than that of hydrogen gast." 



It is truly fatiguing to wade through such an inundation of 



* T/iomson's Attempt, i. ^0. r Ibid. i< 71. 



