362 Dr. Thomsm*s Armoer to Mr, Rainy, [Nov. 



others have both fully established the fact that the lis:ht of 

 the moon has the power of imparting the e^reen colour to plants, 

 although of a tinge less deep than that occasiomd hv tin; light 

 of day. Fitliis also that have been kept exxluded iroin the sun 

 are found to ripen with considerable rapidity when exposed to 

 the lunarrays. ' / • " • '^ '•/" ' 



Finally, it may be stated^ the several specie* f^fwV^K tlittVfc^- 

 posethe solar beam would appear to ejiert the following 'l^;*^nc 

 but varied actions. . * jcjoibv 



First, the calorific rays: they impart heat to the ' different 

 combinations of matter, organic as well as inorganic, and iliius 

 assist in the various chemical changes to which they are ittcliis- 

 santly subjected. u '.•.n^ 



Secondly, the calorific rays by which theobjects that feUWUftd 

 us are illuminated, and but:,f0c fwhicdi'jit'il'Jobvious all 'nAtAVe 

 would be as a dreary blank.' ;f>!f'n o.'i* ''^' h^'h/oi ir»',<ji'» 



Lastly, the deoxydizing or chemical rays, by means of whi<ih 

 (it is suggested) the oxygen consumed during combustion, respi- 

 ration, and a variety of other processes, is again restored to the 

 atmosphere, thus preserving this medium in a state cohstttkitfly 

 fitted for administering to the support of organized being^i'^^-'"* 



.g,^ m\i f ^^ 



Article VIII. 



Answer to Mr, Rainy's Faper on the S^fcifiQ^.^ Gemiyiai^^ 

 Hydrogen Gas, By Thomas Thomscj|^,!)Siip^»J^^^ ^j^ 



In the Annals of Philosophy for August last (Vol. t.j^Vite, 

 New Series), my friend Mr. Rainy has endeavoured to shOvi^ that 

 I have underrated the quantity of vapour in hydrogen gas, by 

 making its specific gravity too low; and that when the errors in 

 my calculations are corrected, the specific gravity of hydrogen 

 gas is to that of oxygen gas not as I have supposed, as 1 to 16, 

 but as 1 to 16*54, or as 0-967 to 16. He draws as a conclusion 

 that my experiments disprove the hypothesis that the specific 

 gravities of all the gases are multiples by integer litlVhbers of the 

 specific gravity of hydrogen gasj • "" '->'>. '^^' ^^' 



I was anxious, before answering-thiB papiir'drMr. Rainy, fb 

 make a few additional experiments on the subject ; and afs'the 

 manipulations were rather delicate, I thought it requisite 'id tWe 

 first place to get ray balance put into the best possible order, sind 

 my weights adjusted so as to render the unavoidable errors iri 

 weighing as trivial as possible. My friend Mr. Crichtdil, to 

 whose uncommon zeal, abilities, and accuracy, I have bd^i 

 already so frequently indebted, was kind enough to'|^ut rtty 

 balance into excellent order; but it vy^s almost the middle. Df 

 September before I was able to tjiecute the pi*o}€ote4 ex|>^^ 

 ments. > ♦ ^ 



