GASES IN THE ATMOSPHERE. 433 



2. It' 100 meafures of common air be put to 3S of pure jviixture loo air 

 nitrous gas in a tube :}-10th oF an inch wide and 5 inches long, and 36 n. gas la 

 after a few minutes the whole will be reduced to 79 or 80 R^^jj^g ^1^^^^^^] 

 meafures, and exhibit no Hgns of either oxygenous or nitrous 80 azote., 

 gas. 



3. If 100 meafures of common air be admitted to 72 of Mixture 100 air 



•nitrous c^as in a wide velFel over water, fuch as to form a Uiin and yzn. gasxa 



Itratum of air, and an immediate momentary agitation be uted, wicTi agitation. 



there will, as before, be found 79 or 80 raeafares of pure Refidue as be- 

 r ^ , fore 80 azote. 



azotic gas tor a refiduum. 



4. if, in the laft experiment, lefs than 72 meafures of nitrous Intermediate 

 gas be ufed, there will be a refiduum containing oXygenoirs P^l'^^^^^^" °.^j"* 

 ga$;'' \? more, (hen fonie refiduary nitrous gas will be found, n. gas or oxigea 



Thefe fafts clearly point out the theory of the procefs : the "Z^^ ^^^ ^zote* 



, ^ ^ ^ ,. ./ .^. ..Theory ot the 



elements or oxygen may combine with a certain portion oip,ycefs, 



nitrons gas, or with twice that portion, but with no inter- 1" '^^ lirft cafe 



mediate quantity. In the former cafe 7iitric acid is the refult; formed • iir^hc 



in the latter nitrons acid : but as both thele may be formed at^-^ttei' nitrous, 



the fame time, one part of the oxygen going to one of nitrous 



^as, and another to tivo, the quantity of nitrous gas ablorbed 



ihould be variable; from 36 io 12 per cent, for common air. 



This is the principal caufe of that diverfity which has fo rauctj 



appeared in the relults of chemifts on this fubjed. In ia&, all 



the gradation in quantify of nitrous gas from 36 to 72 may 



^aftually be obferved with almofpheric air of ihe fame purify; 



ihe wider the tube or vetTel ihe mixture is made in, the quicker 



the combination is efFe^led, and the more expofed to water, 



the greater is the quantity oi nitrous acid and the lefs oUiitric 



that is formed. 



To uia nitrous gas for thfr pufcpofe of eudiomelry therefore, praQJcal reWt. 

 we muft attempt to form nUric acid or intrcus wholly, and Operate fo as t« 



•,, , . , /. I ,1 ^,- . /• ■ ,. form the nitric 



Without a mixture of the other. Ot (hefe the former appears „as. 



from my experiments to be moft eafily and mofl accurately 

 effe^ed. In order to this a narrow tube is necedary; one that 

 is juft wide enough to let air pafs water without requiring the 

 tube to be agitated, i.s beft. Let little more nitrous gas thai> 

 is fufficient to form nitric acid be admitted to the oxygenous 

 gas; let no agitation be u^ed ; and as foon as the dirainulioa 

 appears to be over for a moment let the refiduary gas be trans- 

 ferred to another tube, and it will remain without any further 

 diminution of confcquence. Then fj- of the lofs will be due 



te 



