A 



JOURNAL 



OF 



NATURAL PHILOSOPHY, CHEMISTRY, 



AND 



THE ARTS. 



JULY, 1804. 



ARTICLE L 



On ihefuppofed Chemical Affinity of the Elements of Common Air; 

 niih Remarks on Dr. Thomfon's Obfervations of that Subject, 

 In a Letter from Mr. J. Dalton. 



To Mr. NICHOLSON. 

 SIR, 



In a former letter, inferted in your Journal (new ferles, vol. Difficulties re- 

 III. page 267) I endeavoured to (hew the abfurdity of the no- ^^^^^^l 5:hat at. 

 tion of atmofpherical air being a chemical compound of azotic mofpherlc air is 

 and oxigenous gafes. Befides the difficulty, or rather irapoffi- ^'^^J^'J^'"' """* 

 bility on the one hand of conceiving how two elementary par- 

 ticles, conftantly repelling each other, fliould notwithftanding 

 be held together by a principle of cohelion or chemical affinity ; 

 or on the other hand, fuppofing the two atoms to combine, 

 and form one centre of repulfion, how atmofpheric air fliouId 

 differ from nitrous gas, &c. There are a variety of fads which 

 oppofethe dodlrine fo forcibly that I have for fome time won- 

 dered on what grounds thofe who are ftill its adherents de- 

 fended it. Dr. Thomfon, in the fecond edition of his che- Dr. Thomfon's 

 mifty, vol. III. page 316, after reviewing the opinions of dif- ^^^"^^^"^'^1^"^ 

 ferent phiiofophers on this head, and amongft others my own, dodlrlne, 

 concludes that air is a chemical compound; he afligns the four 

 following reafons for the conclufion, which, from his extenfive 

 Vol. VIII.-^July, ISO*. ,L ac« 



