$60 Experiments on the Nature of [Nov. 



N = nitric, O = oxygen* and P = lead (pharhum). Az + 

 5 O, according to Sir Humphry Davy, is nitric acid; and Az 

 4- 4 O, nitrous acid. According to the result of my experi- 

 ments, nitric acid ought to be represented by N + G O, and 



let us write Az O, N O, ike. instead of Az + 5 O, 

 nitrous acid by N + 4 O. To abbreviate these signs a little, 

 N 4- 6 O. 



The formula which represents the nitrate of lead is then 



s 



Az O + O P, and that which represents the neutral nitrite 



4 



must be Az O + P O. Hence it follows, that in order to 

 reduce the nitric to nitrous acid we must add another P, and we 



4 _ 



shall have Az O + 2 P O. There will be no disengagement 

 of nitroiis gas ; and when the nitrate has dissolved as much lead 

 as it originally contained, no nitric acid can remain in it. Every 

 portion of lead added beyond that quantity will occasion a dis- 

 engagement of nitrous gas, and will form a nitrite containing a 



4 



still greater excess of base, namely, Az O + 4 P O. Let us 

 examine whether this happens or not. 



In my experiments on the formation of nitrite of lead, I have 

 proved that the solution of the lead was always accompanied by 

 the disengaoenu/it of -nitrous gas. This circumstance appears at 

 first to give a decisive proof against the determination of Davy; 

 but this proof is only apparent ; for whatever be the composition 

 of nitrous acid, it is easy to prove that its formation ought 

 alw;:ys to take place without the evolution of nitrous gas, in 

 consequence of the property which the two acids have of forming 

 subsalts in different degrees of saturation ; and if we consider 

 the evolution of nitrous gas as a necessary consequence of the 

 formation of nitrous acid, it will not be possible to form any idea 

 of the inteiior of the operation. The disengagement of nitrous 

 gas depends upon another cause, which 1 have already pointed 

 out in my memoir on the nitrites. {Ann. de Chim. July, 1812.) 

 It is owing to the propeity which the neutral nitrites have of 

 being ''^composed at a temperature between 1/7° and 212°, 

 with the disengagement of nitrous gas, and the formation of 

 sublimates ; and this happens equally, though there be no lead 

 to dissolve. This disengagement is much slower, if the solution 

 be dilute ; but in concentrated solutions it takes place with 

 effervescence. We must, then, ascribe the evolution of nitrous 

 gas in the above experiment to the decomposition of a small 

 portion of nitrite immediately alter its formation. To prove the 

 truth of this opinion, 1 digested a solution of ten parts of neutral 



to urdersfand these formulas. The only thins: that remains to render the use 

 of them more general, is to determine correctly the specific gravity of the 

 jjases. 1 shall publish ber;. after a dissertation upon this subject. 



