New Outlines of Chemical Philosophy. 1 9 



CE, the resXilt arising from multiplyincf n — h by c—d. Now in 

 the formula ca — cb — fln-\-(lL< we are directed first to take from 

 AF ; CF, and then EF, but the rectangle GH being common to 

 both CF and EF, lias been ah-eady taken away when we took 

 away CF, and as in the algeljraical formula this cannot be told, 

 we take away the Avhole rectangle EF, and then add the rect- 

 angle GH, which if it had been taken out of the rectangle CE 

 would evidently have left the result of the operation too small. 



III. New Ouili?ies of Chemical Philosophy. 

 By Ez. Walker, E<iq. of Lynn, Norfolk. 



[Coiitinueii from vol. xliv. p. 4-41.] 



X HE composition of the atmosphere is still but imperfectly im- 

 derstood. It is said that it consists of 21 per cent, of oxygen 

 gas and 70 of nitrogen ; but it is well known that hydrogen and 

 carburetted hydrogen gases arise from various species of vege- 

 table and animal decay and putrefaction, and in great abundance 

 from marshes and stagnant pools of water, especially in hot 

 woather. Consequenily those gaaes would soon contaminate 

 the atmosphere to such a degree, as would render a country un- 

 inhal)itable, were it not for the natural means by which those 

 gases are decomposed and returned to the earth. Hence it is 

 probable that the upper parts of the atmosphere generally con- 

 tain a large portion of those gases. 



The air upon the tops of mountains is much colder than in 

 the valleys, because hydrogen gas, being much lighter than at- 

 mospheric air, rises in great al)undance into the higher regions ; 

 but oxygen gas cannot ascend so high, in consequence of its 

 being many times heavier than the other. 



Hence, the temperature of the air in the higher regions can- 

 not be e(]ual to its temperature upon the surface of the earth 

 wheic those gases are in a more condensed state*. 



" In every case of combustion there must be present a com- 

 bustible and a .supporter ;" nor can the temperature of a body 

 be increased without these two elements be united. 



To illustrate this position by experiment ; Let two pieces of 

 dry wood be smartly rubbed together, and an increase of tem- 

 perature will be generated long l)efore combustion takes placet- 

 Couse(juently combustion and increase of temperature are effects 

 vj the same cause. 



' Phil. Mag. vol. xliii. p. ]03. f Ibid. p. 103. 



B2 But 



