ON MIXED GASES. ^71 



and to repeat experiments confidered as decifive, erpecially Obfervatlons oa 

 ?s they are of a fimple nature. All the chemifts of Europe j^^[;^^°"^^^*^^ 

 fecm to be agreed, that either 21 or 22 per cent, in bulk, is gafes. 

 the proper number. My own experience gives 2 J for the 

 iieareft integer, which agrees with Mr. Davy's in your Journal, 

 (quarto Series), Vol. V. page 175 : if Mr. G. entertains any 

 doubt on the fubjeft, I would refer him to that paper, and he 

 will receive ample fatisfaiflion. 



After what has been faid, I think Mr. G. rauft be fatisfied 

 that he has virtually demonftraled the atmofphere to be a me- 

 chanical mixture of the two gafes ; If, however, he (till 

 alledge that I only oppofe one authority to another, and that 

 his is as good as mine; then I would recommend him to 

 fatisfy himfelf as follows: mix 21 parts (or a quantity of gas 

 containing 21) of pure oxigen, and 79 of pure azote, toge- 

 ther; after this proceed to the analyiis of the gafes, and exa- 

 mine the differences between the refults, and tliofe done from 

 the analyiis of 100 parts of atmofpheric air. 



I cannot conclude thi>? article without obferving, that Mr. G, 

 mufl have been totally unacquainted with the opinions of chemi- 

 cal philofophers on the fubjeft, or he would not have expanded 

 into the compafs of five or fix pages a fimple argument, which 

 has often been adverted to by others, and is now wholly 

 abandoned as untenable. Mr. Davy, in his Refearches, 

 publifhed in 1800, advocating the notion of almofpherical air 

 being a chemical compound, produces four evidences, one of 

 which is flated as follows ; See Page 326. 



** 2dly, The difference between the fp.gr. of atmofpheric 

 air, and a mixture of 27 parts oxigen and 73 nitrogen, as 

 found by calculation ; a difference apparently owing to ex- 

 panfion in confequence of combination." In a note he adds, 

 ** The two firft evidences have been often noticed." This 

 gentleman however foon after, finding that the atmofphere 

 contained only 21 percent, of oxigen, mufl have feen that this 

 evidence was not to be admitted. Since that time it has not 

 been urged by any one to my knowledge. 



I come next to Mr. G.'s reply at page 160. This at the 

 commencement purports to be a defence of the charge, that 

 my argumenis are but few, and negligently conduced ; at the 

 conclufion it is afferted to be an anfiuer to all my ohjeSiiom, 

 and fojnething more. This language may be that of logical 



precifion 



