22a COMPOSITION OF WATER, &C* 



oxigen and hidrogen gafes, the heat produced Is fo a6iiv6 

 as to make an explofion of the gafes; but if a flow combuC- 

 tion, it will leave the oxigenized acid in a gafeous ftale, as 

 carbonic acid gas, which, I fuppole, was the cafe in Mr. 

 Northmore's experiments. His next experiment of examin- 

 ing the acid : He comprefied the gafes upon two fcruples of 

 the folution of potafli ; he fays, " there was fcarce enough 

 acidity to tinge the edge of the ted paper ; of courfe, I could 

 not effe6l the formation of the nitrate of polafli." But always 

 to afljgn fome reafon for the failure, he fays-, "This quantity 

 (of gafes) was hardly fufficient for the receiver's capacity;" 

 but there was the fame quantity in this experiment as in the 

 others; nay, in the next experiment (the fixth) there was 

 identically the fcniie quantity and in the fame proportions ; and 

 in this fifth experiment, he found fo liitle acid, as he fays, 

 •^ Scarce enough acidity to tinge the edge of the teft paper ; 

 of courfe I could not effedl the formation of the nitrate of 

 potafli." Now upon the fuppofilion that the carbonic acid 

 was formed, it would unite with the po!a(h, and therefore 

 the mixture would be lefs falurated with it: But if the acid 

 was fa ftrong as he fpeaks of n\ the fixth experiment, from the 

 very fame procef^, as he fays, •« VVIiich moifhire was ftrongly 

 acid to the tafte, coloured litmus, and when very much di^ 

 ]uted with water, a6ted upon filver." Now if Mr. Northmore 

 will confult the writings of chemifts, (Dr. Black's lectures, for 

 inftance) ; in Vol. II. the do61or fays, *• that the nitric acid 

 lequires a litlie water to reduce it to the flrength of aqua for-. 

 tis; in order to aft upon fiiver, tiierefore, in this experiment, 

 the acid niuft have been in the concentrated ftate of (he nitric 

 acid, as it required water to be diluted to make it act upon 

 filver; but probably Mr. N. does i.«>t know that water im- 

 pregnated with hidrogen gas will colour filver; which I fup- 

 pofe to have been the cafe here. 



This reafoning mud: appear to be moft extraordinary: this 

 vad quantity of nitric acid produced was even to penetrate 

 into the cap of the receiver ; but very unfortunately for this 

 fuppofition, chemirts are of opinion that acids will not dif- 

 folve refms. Mr. Halchett has promoted their operation upoh 

 each other by ufing the firong nitric acid ; but this was a diflS-, 

 eult and tedious procefs, not during the tranfitory a6lion of a 

 little lime, by compreffion ; and where toe refin was io con-» 



cealed j 



