Page:Proceedings of the Royal Society of London Vol 1.djvu/302

Rh and in the same manner, that 100 parts of soda contain 81 base and 19 oxygen.

The other method consisted in collecting the hydrogen evolved from water by a known quantity of each base, and estimating from them the quantity of oxygen absorbed. The mean of two such experiments on the base of potash, gave the proportion of 15% per cent. oxygen, and the mean of three trials upon soda, showed it to contain 20 per cent. oxygen.

So that the general average of both methods authorizes us to consider potash as containing 15 of oxygen, and soda 20 of oxygen, per cent.

Since oxygen had thus been proved to enter into the constitution of the ﬁxed alkalies, Mr. Davy was led to conjecture that it might also form a constituent part of ammonia. For though the apparent conversion of ammonia into mere nitrogen and hydrogen in the experiments of Scheele and of Priestley, as well as in the more reﬁned and masterly experiments of Berthollet, had left no doubt of its nature on the minds of chemists in general, it was not impossible that a small quantity of water in their results might have been overlooked, when dissolved in the gases or deposited on the vessels employed, or might even be neglected, as not arising from elements essential to the construction of the ammonia. His conjecture was conﬁrmed in the ﬁrst place by the formation of carbonic acid in the purest and driest ammoniacal gas, by means of charcoal intensely ignited by a voltaic battery.

When Mr. Davy had afterwards exposed the base of potash to ammoniacal gas, and had ascertained the formation of potash, no doubt was left of the presence of oxygen, although its proportion could not by these means be ascertained. For the purpose of determining the proportion, and at the same time of avoiding any fallacy that might be occasioned by the presence of water in the ammoniacal gas, even in its state of hygrometrical dryness, Mr. Davy had rccourse to the apparatus employed by Messrs. Allen and Pepys for the combustion of the diamond. The gas, after being carefully prepared and dried, was passed over the surface of iron Wire ignited in the platiha tube, furnished with an additional apparatus for condensing any water that might be formed in the experiment.

In the course of a quarter of an hour four grains of ammoniacal gas were decomposed. The iron wire had gained {ﬁfths of a grain. and a quantity of water was moreover collected, which weighed full four tenths of a grain. From the amount of the oxygen contained in the water, together with that which caused the increase of weight in the iron, Mr. Davy infers that 100 parts of ammonia contain nearly 20 of oxygen.

We may therefore consider oxygen as existing in, and as forming an essential element of all the three alkalies; so that this principle of acidity, as it is termed in the French nomenclature, might now equally be called the principle of alkalization.

From analogy alone, it is reasonable to presume that the alkaline