this experiment intense ignition took place at the point of contact of
the substances, the potassium appearing to bum by oxygen acquired
from the acid, of which eight grains saturated about twenty of potassium.
The residuum did not effervesce in water, which merely dissolved some sub-borate of potash which is formed, and leaves exposed the boracic base as a spongy mass, black in some parts, and dark olive in others. It appeared to be infusible by heat, but a perfect conductor of electricity. When acted upon by nitric acid, or burned in oxygen, it was reduced again to the state of boracic acid, probably much heavier than the basis from which it is formed.
When fluoxic acid gas was acted on by potassium, fourteen cubic inches disappeared by means of ten grains and a half of potassium, and about two inches and a quarter of hydrogen gas were evolved, apparently from water contained in the gas. In this experiment, a brownish sublimate was sometimes raised by the heat generated, and at others, a blackish matter remained mixed with a quantity of fluate of potash that is formed. -
This matter appears to be fluoric acid, deprived of oxygen, and existing in a state analogous to that of sulphur and phosphorus; for when the sulphuric or phosphoric acids are decomposed by potassium, the pure bases are not evolved, but sulphurets and sulphites, phosphorets and phosphites, are generated.
Although the attempts to decompose the muriatic acid have not hitherto been equally successful with the preceding, yet many new and interesting results were obtained. When a quantity of potassium was employed, sufficient to absorb a given quantity of this gas, so much hydrogen was evolved as to prove that it contains full one third its weight of water.
Various attempts were made in consequence, to obtain the acid free from water, but they only terminated in new and singular combinations.
By burning phosphorus in oxymuriatic acid, a very volatile compound was obtained, consisting, apparently, of muriatic acid and phosphoric acid in a dry state, and a second compound of phosphorous acid with muriatic also, free from water. Corresponding products were also obtained by means of sulphur, consisting of dry sulphuric and muriatic acids; and the most remarkable circumstance attending these compounds. is, that they do not redden litmus paper, and manifest no marks of acidity till water is added to them.
In exposing potassium to these compounds, a violent detonation takes place, and Mr. Davy has some reason to hope that the muriatic acid suffers decomposition at the time, but he has not yet been able to collect the products for examination; and the elements of this acid, if separable, must remain a subject for future investigation.
