+------+-------+--------------+---+------+------+---------+---------+ | | |100 Cubic In. | |grains| |Nitrogene| Oxygene | | | +--------------+---+------+------+---------+---------+ |Nitro-| With | Nitrogene | | 30.04| | | | | gene | Oxy- | Oxygene | | 35.06| | | | | | gene +--------------+---+------+ 100 +---------+---------+ | | |Atmospher. air| w | 31.10|grains| 73.00 | 27.00 | | | |Nitrous oxide | e | 50.20| are | 63.30 | 36.70 | | | |Nitrous gas | i | 34.26|com- | 44.05 | 55.95 | | | |Nitric acid | g | 76.00| posed| 29.50 | 70.50 | | | | | h | | of +---------+---------+ | | | | | | |Nitrogene|Hydrogene| | +-------+--------------+---+------+ +---------+---------+ | | With | | | | | | | | | hydro-|Ammoniac | | 18.05| | 80.00 | 20.00 | | | gene | | | | | | | +------+-------+--------------+---+------+------+---------+---------+ No. III. _Additional Observations._ _a._ In Res. 1st. Div. IV. Sect. III. in the analysis of nitrous gas by pyrophorus, as no absorption took place when the residual nitrogene was exposed to water, I inferred that if any carbonic acid was formed it was in quantity so minute, as to be unworthy of notice. A few days ago, I compleatly decomposed a quantity of nitrous gas by pyrophorus, when the residual nitrogene was exposed to solution of strontian, the fluid became slightly clouded; but no perceptible absorption took place. _b._ If there was the least probability in any of Dr. Girtanner’s speculations on the composition of Azote,[235] the experiments on the exhausted capacity[236] of the lungs in Res. III. might be supposed inconclusive. But there appears to be no more reason for supposing that hydrogene is converted into nitrogene by respiration, than for supposing that it is converted into water, carbonic acid or oxygene; for all these products are evolved when that gas is respired. From the comparison of Exp. 1 with Exp. 3, Res. iii. Div. ii. Sec. 4, it is almost demonstrated that no ascertainable change is effected in hydrogene by respiration. The experiment of the accurate Scheele in which hydrogene after being respired thirty times in a bladder wholly lost its inflammability, may be easily accounted for from its mixture with the residual gases of the lungs. [235] Annales de Chimie, 100; and Mr. Tilloch’s Phil. Magazine. 24. [236] I regret much that I could not procure Dr. Menzies’s observations on Respiration, while I was making the experiments on the capacity of the lungs: they would probably have saved me some labor.