£2 



PROPORTION OP LIGHT AFFORDED BY CANDLES. 



M i3 

 »- c 



£1 



1 



2 

 3 

 3 

 4 





Light 



by 



Rule I. 



Light 



by 



Rule n. 



2d Rule 



differs from 



the J ft. 



No, 1. compd. with the mould 

 No. 1 . compd. with do. 

 No. 1. compd. with do. 

 No. 3. compd. with do. 

 No. 4-. compd. with do. 



1.000 

 1.000 

 1.000 

 1.196 

 1.196 



1.000 

 1.000 

 1.015 

 1.125 

 1.226 



.000 



.000 



+ .015 



- .071 



+ .030 





The mean error 



of the 2d Rule 



- .005 



As the mean refult given by the 2d rule, differs only 1 in 200 

 from the ift, which is univerfally received as true, the 2d rule 

 appears fufficiently exa6l for many pradical purpofes, where 

 the properties of that light is concerned, which is produced 

 by candles. 



EZEKIEL WALKER. 



Lynn Regis, 20th Sept. 1803. 



Whether the P. S. As to your correfpondent*s experiment, it does not 



cSpondenJ'be ^^^^^^ ^° ^^'^'^^ ^"^ '^^' ^' '^ appears to himfelf ; for every one 

 ■ccurate. knows, that one end of a mould candle is thicker than the other, 



therefore if that gentleman made his experiment with the fmall 

 end of his candle, he has eftimated the quantity of light pro- 

 duced by a pound, too little ; and if he made his experiment 

 with the large end, his eftimation is too great ; and moreover, 

 it may be doubted, whether the -^ part of a pound of candles, 

 can be fo exadtly afcertained by meafuring as by weighing, 

 even if the candles were perfed cylnders. 



IX. 



On tlie Compounds of Sulphur and Oiygen. By Thomas 

 Thomson, Af. Z>. Ledurer on Chemijtry in Edinburgh. From 

 the Author. 



Three known 

 compounds of 



IT is at prefent the opinion of Chemills that fulphur is capa- 

 y^nj^i.^oxioeV^'^ "^ Combining with three dofes of oxygen, and of forming 

 three diftindt compounds, namely, 



l.».Px.ide of Sulphur. 

 2.- Sulpliurous Acid. 

 3. Sulphuric Acid. 



The 



