CHEMICAL EKJ'ECTS OF LIGHT. 293 



4. The yellow nitrate of Proufl contains the fame oxide as 

 common nitrate. But in it there is noexcefs of acid; whereas 

 common nitrate is in fadt a fupernitrate of lead. In a ftrong 

 heat it is partly converted into a fuhniirate. 



5. Protoxide of lead unites with all acids, dcutoxide with 

 none, and peroxide only with hyperoxymnrialic acid, 



6. The protoxide of lead may be formed by combuftion; 

 but the other two cannot, and indeed lofe oxygen in a ftrong 

 heat. The deutoxide is formed by keeping protoxide in con- 

 tact of air at a given temperature : the peroxide by the aftioii 

 of nitric or oxymuriaticacid on the deutoxide. 



XI. 



On certain Chemical Effeds of Light. In a Letter frum Wm. 

 Hyde Wollaston, M.D. F. R. S. 



To Mr. NICHOLSON. 

 SIR, 



Had I forefeen the publication of Mr. Ritter's < Experi. '^'^troAuahn on 



,.,,.,, o T c T 14-1 It the invihble rays 



7nents on Light m the lalt number or your Journal,'' L would j^at havechc- 



have requefled you to accompany them with a few obfervations micaleflFeas. 

 of mine on the fame fubjed ; not with a view of claiming any 

 priority in the obfervation of thofe invihble rays, that have 

 chemical efFeds, which I believe occurred to Mr. Ritter and 

 myfelf very nearly at the fame time; but for the purpofe of 

 inferting a caution againft tiie theory implied by the term '< dif- 

 oxidating" as applied to thofe rays. 



In my note upon a communication to the Royal Society,! The power of 

 ., ••ii^Lxrir tnefa rays was 



which you did me the honour to reprint in the 4.th Voi. of your termed chemical 

 fournal, t I was careful to exprefs the power exerted by the by Dr. w. and 

 moft refrangible rays on muriate of filver, in general terms as becalfrthey''do 

 chemical, not merely from a doubt whether they would in other not conftantly 

 cafes produce a correfponding effe^, but becaafe I had at that d-foxi'iate. 

 time made the following experiments, which proved that the 

 fame rays, which caufe the emiffion of oxygen by muriate of 

 filver, occafion its abforption by the refin ufually called gum 

 guaiacum. 



♦ Page 214. f Phil. Tranf. 1802, p. 379. J 8vo. feries. p. 99. 

 ^ My 



