of Azole wit k Oxygen. S^tS 



binatlon, it appears iome that it ought to be ascribed to the 

 li'.'.niidity of the air, or to that which remains attached to the 

 vessels, and which it is impossible entirely to get rid of in mani- 

 pulations which are a little complicated. Besides, this acid is 

 not exhibited under the orange colour, but when it is anhy- 

 drated ; for I have remarked that the smallest quantity of water 

 is sufficient to render it green, as will be explained a little lower 

 down. The licjuid acid obtained from the distillation of the 

 nitrate of lead does not therefore contain Vvaler, nor does 

 the nitrate of lead dried contain any. On calculating the 

 ratio of the azote with the oxvgen in the liquid acid according 

 to the above results, we find that 100 parts of azote are com- 

 bined with 233"S of oxygen. These proportions differ very Httle 

 from those which we may deduce for the composition of the 

 nitrous acid gas from the ratio in point of volume which M. 

 Gav Lussac has given ; for we hnd, on setting out from tliis 

 ratio, for 100 of azote, "228 of oxygen. The identity of the ni- 

 trons acid gas and of the liquid acid obtained by the distillation 

 of the nitrate of lead seemed to me at first so extraordinary, that 

 1 thought some error had slipped into the weights ; but after 

 having repeated several times the same experiment, with results 

 verv little different, there did not remain a doubt as to this iden- 

 tity. It then became very evident, that the nitrous acid gas 

 cnnld not be a permanent gas. In order to verify this inference, 

 I made the following experiment : 



I placed in two cylindrical reservoirs two bell-glasses with 

 cocks, one containing nitrous gas and the other oxygen gas: by 

 means of two funnels with stop-cocks, in which water was kept 

 constantly at the same level, I regulated the flowing of this liquid 

 into the two reservoirs, so that the quantity of nitrous gas dis- 

 placed bv the water in one of the bell-glasses was a little less 

 than the double of the oxygen extricated, during the same time, 

 from the other bell-glass; both gases severally passed through 

 a long tube partly filled with nmriate of linie and partly with 

 quick lime, and afterwards met in a tube of a larger calibre con- 

 taining fragments of porcelain: i)y this arrangement, the gases 

 mixing perfectly, they are transformed into nitrous vapour al- 

 most pure, and merely containing a small excess of oxvgen. The 

 gaseous mixture afterwards passed into a curved tube, submitted 

 to an artificial cold of 20" below zero. y\fter having passed 

 some litres of gas over into this apparatus, I obtained in the 

 co(jled tube a slightly greenish liquid, sending out into the air 

 very abundant yellow vapours, and which was transformed during 

 decantation into an orange yellow litiuid possessing all the pro- 

 jjorties of that which proceeds from the distillation of the nitrate 

 ol' lead. This e.xpcriincnt docs not allow of any doubt, and we 



ought 



