CONSTITUTION OF MIXED GASES. 297 



piece of paper Was therefore ftained with guaiacum and after 



being rendered green by expofurefor a fufficient length of time 



to light, was prelTed on its pofterior furface with a filver fpoon 



previoufly heated over the flame of a candle ; and the green 



colour was thereby as efiedualiy removed, as in the focus of 



folar heat. 



The lafl experiment may poffibly appear to have been un- Radiant fohr, 



neceflary ; hut until it is explained why the heat, that accom- teat penetrate* 

 , . I- r tranrxirent 



panies the fun's rays, penetrates the fubfiance of tranfparent bodies; culinary 

 or fenii-tranTparent bodies, while the radiant heat from a fire "^^'a^'onfcareci/ 



1 /• I n r 1 2t all. 



has Icarcely power to enter even the molt tranfparent, but 

 principally fcorches the furface, and is thence flowly condu«5led 

 into the interior parts: no degree of caution upon a fubje6l fo 

 imperfedtly underftood, ftiould be deemed fuperfiuous. * 



I remain. Sir, &c. 



W. WOLLASTON. 



xir. 



Illujirations of Mr. Dalton's Theory of the Confiitulion of Mixed 

 Gafes. In a Letter from Mr. Wm. Henry, (/ Manchejler, 

 to Mr. Dalton. Communicated by the Writer,* 



To Mr. DALTON. 

 Dear Sir, 



N the firfl: enunciation of a new theory, it is not unufual Caufes whyi 



I 



that fome links are omitted in the chain of reafoning, which ""^ '^'^^°''y ^^J 



° not readily pro- 



led to its formation; and thus the dodrine fails or that ready duce conviftion 

 and general acceptance, which immediately follows its more and adoption, 

 diftind development. Such an omilTion appears to me to have 

 taken place in your Theory of the Conltitution of Mixed 

 Gafes; for, according to your own candid confefTion, feveral 

 perfons, verfed both in chemical and mechanical fcience, have 

 declared their inability fully to underftand ihe fcope of the hy- 

 poliiefis, and confequently to judge of its merits or defects. 

 In the difcufiions alfo, which took place in this Society, on 

 your feveral papers, the doctrine was oppofcd by almoft every 

 member interefted on fuch fubjects, and by no one more flre- 



* Read before the Manchefter Society. 



nuoufly 



