I 



of Azote with Oxygen. -33S 



have analysed tliis liquid by the process which I hnve described 

 above for the aiialvsis of dry nitrous acid ; and I found that it 

 was formed of 100 parts of azote and 207 parts of oxygen, in 

 weight, in one cscperinient ; in anotiier, I found 210 parts of 

 oxygen for the same quantity of azote. It is evident, beside.', 

 from the way in which this liquid has been formed, that water 

 does not enter into its composition. Tiie proportion of oxygen 

 which it contains is less than that of the nitrous acid ; hut it is 

 greater than tliat which ought to be found in the acid of the 

 liilrlles, which (iay Lussac has denominated pernitrojis. 



It is ])r()bab!e, according to this, that it is not a homogenecus 

 combination, l)ut a simple mixture of dry nitrous acid, and an- 

 other comp;>uu(i of nitrous and oxrgcn gas, in which the pro- 

 portion of nitrous gas will be much stronger, and this conjec- 

 ture Is also supported bv the manner in which tiiis li(juid acts 

 during its di'.tiliation. In fact, by submitting it to a geiille heat 

 the green colour gradually l>ecomes weaker as the volatilization 

 is effected, and there remains a variable quantity of dry nitrous 

 acid. If the green liquid is not a sim])le solution of nitrous gas 

 in dry nitrous acid, it ought to contain another combination of 

 nitrous gas and oxyeen, probably in the proportions of the per- 

 nitrous acid, which it will perhajjs be possible to ii..s;ilate by re- 

 iterated di^tiilations, since there exists a diiierence, although in 

 truth very feeble, between the temperatures of ebullition of the 

 green and the orange liquid. T'li; is a question v.hich I shall 

 endeavour to decide on account o: its importance, notwithstand- 

 ing the difficulties bv which it is surrounded. When we place dry 

 nitrous acid in contact with a great quantity of water, by im- 

 mediately shaking the mixture it is instantaneously decom- 

 posed ; a proportion of nitrous gas is extricated, which varies 

 accordinir to the rapidity with which the decomj)osition is effected. 

 If we put, on the contrary, a very small quantity of water with 

 the same acid, no gas is disengaged ; but the acid becomes a very 

 deep green : this is what happens when we ]J0ur, drop by drop, 

 dry nitrous acid into anv mass of water ; because this acid being 

 heavier than water, it gains the bottom of the vessel, undergoing 

 the change of colour just mentioned. It is evident, from what 

 has been said, that the conversion of the orange acid into green 

 acid, in this circumstance, ought to be ascribed to the decom- 

 position of a part of the dry nitrous acid into nitric acid which 

 is dissolved in the water, and in nitrous gas which is combined 

 vitli the remains of the non-decomposed acid. Lastly, if we 

 mix successively with a certain quantity of water various por- 

 tV)ns of nitrous acid, the extrication of nitrous gas produced by 

 the same weight of acid will always <liminisb, until it ceases en- 

 tirely, although the liquid continues to absorb nitrous acid. We 



then 



