^{page 336 note *} If the Chloridic Theory be still retained, then the production of water in the above circumstances can be ascribed only to the decomposition of azote into oxygen and hydrogen, as has been already indicated in my paper on the Ammoniacal Salts. It is possible that this alternative may eventually be found the true one; yet in the present state of our knowledge, such an inference would be illogical.

^{page 338 note *} The price of the apparatus is about three guineas.

^{page 339 note *} In the figure, the ball should have been represented pendent from a hook.

^{page 349 note *} If mere heat can separate the combined water of sal ammoniac, then the salt, which, after passing through ignited quartz, has concreted on the verge of ignition, being nearly anhydrous, will, in an equal weight, contain more acid than before transmission. It will in fact bear the same relation to common sal ammoniac, that ignited sulphate of soda does to the crystallised salt. Having transmitted, in the state of vapour, the salt condensed from the dry gases, through ignited quartz, I took 10 gr. of the cake, consolidated just beyond the quartz; and dissolving them in water, decomposed by nitrate of silver, when I obtained 27 gr. of dry muriate of silver, being the quantity precisely equivalent to 10 gr. of ordinary muriate of ammonia. (See WOLL. Scale of Chem. Equiv.) Hence it is evident, that ignited sal ammoniac has undergone no change in its constitution. There was obtained one-tenth of a grain of liquid in that experiment, in which 20 gr. of salt had been passed through the quartz; but this though colourless rock-crystal, betrayed the presence of iron in its composition. For, the liquid stained the paper on which it was withdrawn, of a yellow colour; and the sublimed salt had, faintly, the same hue. The resulting muriate of silver partook, a little, of the brown tinge, of peroxide of iron. I therefore ascribed the production of liquid to the action of the oxide of iron on the hydrogen of the ammonia.

^{page 350 note *} In clear frosty weather, or in a very dry apartment, where muriate of lime would crystallise, the ammoniacal salt acquires weight very slowly. Fifty grains of that from gaseous combination, just heated in a platina capsule, to near its subliming temperature, being put into the scale of a sensible balance, became heavier by half a grain in two minutes; after which, in the above circumstances, no further absorption of moisture was perceptible for an hour. The experiments detailed in the text were made, when the air was considerably loaded with moisture.

^{page 352 note *} M. Gay Lussac, In his Recherches Physico-chimiques, describes a similar experiment, but without the production of water. If the utmost precautions be not taken, to keep the condensing tube at a very law temperature, the expanded and heated acid gas will readily carry off the moisture, as I found in one experiment. The neglect of these precautions will account for the difference of M. Gay Lussac's result.