Note 71 — Chapter VI · TTHE COMPOUNDS OF NITROGEN WITH HYDROGEN AND OXYGEN

Faraday obtained liquid nitrous oxide by the same method as liquid ammonia, by beating dry ammonium nitrate in a closed bent tube, one arm of which was immersed in a freezing mixture. In this case two layers of liquid are obtained at the cooled end, a lower layer of water and an upper layer of nitrous oxide. This experiment should be conducted with great care, as the pressure of the nitrous oxide in a liquid state is considerable, namely (according to Regnault), at +10° = 45 atmospheres, at 0° = 36 atmospheres, at -10° = 29 atmospheres, and at -20° = 23 atmospheres. It boils at -92°, and the pressure is then therefore = 1 atmosphere (see Chapter II., Note 27).