« PrécédentContinuer »
mote the interests of his favourite science by an accurate description of the numerous parts of Scotland and Ireland, whose structure he has ascertained, than by the most ingenious speculations about the origin of the earth. The splendour of such speculations is too apt to have irresistible attractions for a young and generous mind just starting in the arena, and eager to attract the attention of his fellows. But the fate of the numerous list of preceding writers in this tempting career, and the fate obviously impending over even the latest and best qualified adventurers, ought, I think, to be a warning. Who at present ranks the geological speculations of Kirwan, Bertrand, or Lametherie, much higher than those of Woodward or Buffon? And the impending fate of Hutton, and even of Werner, is obvions and irresistible. Facts are eternal, speculations are palaces of ice glittering like gold and jewels, and built apparently of the most solid materials; but melting away before the rays of the sun, without leaving even a trace behind them.
Observations on new Combinations of Oxygen and Acids.
By M. Thenard.* I OBTAINED these new combinations by treating the peroxide of barium with acids. Most of them are very remarkable, and deserving the attention of chemists.
The first that I observed is the combination of nitric acid and oxygen. When the peroxide of barium, prepared by saturating barytes with oxygen, is moistened, it falls to powder without much increase of temperature. If in this state it be mixed with seven or eight times its weight of water, and dilute nitric acid be gradually poured upon it, it dissolves gradually by agitation without the evolution of any gas. The solution is neutral, or has no. action on turnsol or turmeric. When we add to this solution the requisite quantity of sulphuric acid, a copious precipitate of sulphate of barytes falls, and the filtered liquor is merely water holding in solution oxygenized nitric acid.
This acid is liquid and colourless, it reddens strongly turnsol, and resembles in almost all its properties nitric acid.
When heated, it immediately begins to discharge oxygen ; but its decomposition is never complete unless it be kept boiling for some time. It follows from this, that it would be difficult to concentrate it by heat without altering it. The only method which succeeded with me was to place it in a capsule under the receiver of an air-pump along with another capsule full of lime, to exhaust
* Translated from the Ann. de Chim, et Phys. viii. 306. (July, 1818.) Vol. XIII. N° I.
the receiver till the barometer gauge stands 10 or 12 centimetres below the common barometer. By this means I obtained an acid sufficiently concentrated to give out 11 times its bulk of oxygen gas; while in its first state it gave out only 14 times its bulk of that
gas. This acid combines very well with barytes, potash, soda, ammonia, and neutralizes them; but I am afraid that it will scarcely be possible to crystallize the salts thus formed. When heated ever so little, the acid is decomposed, and gives out oxygen. They are decomposed likewise, at least this is the case with the oxygenized nitrate of barytes, when left to spontaneous evaporation. The decomposition takes place at the instant of crystallization. They are decomposed likewise when placed under an exhausted receiver. They have this last property in common with the solutions of the alkaline bicarbonates, which, when placed in an exhausted receiver, boil violently, and are reduced to the state of carbonates. The oxygenized nitrate, when changed into nitrates, do not alter the state of their neutralization.
Thus we see that oxygenized nitric acid, when united with bases, instead of becoming more stable, acquires, on the contrary, the property of abandoning its oxygen with greater facility. This is so true, that if into a neutral and concentrated solution of oxygenized nitrate of potash we pour a concentrated solution of potash, a brisk effervescence takes place, and oxygen is disengaged. The potash acts doubtless upon the nitrate, properly so called. Thus the bases act relatively to oxygenized nitric acid as the ordinary acids relatively to certain peroxides ; sulphuric acid, for example, on the black oxide of manganese.
I have not neglected to put oxygenized nitric acid in contact with the metals. I found that it did not act on gold; that it dissolved very well those metals which nitric acid is capable of dissolving; and that this solution in general took place without the disengagement of gas, and with the production of heat. However, in some cases, there is a little oxygen disengaged at first. This happens when the action is too violent, as is the case when oxygenized nitric acid concentrated so as to contain 15 times its volume of oxygen is poured upon zinc.
One of the most important questions was to know how much oxygen oxygenized nitric acid contained. In order to ascertain the quantity, I began by analyzing the deutoxide of barium. I heated a certain quantity of barytes with an excess of oxygen in a small curved tube standing over mercury. This base, to pass to the state of a peroxide, absorbed almost as much oxygen as it contained; but having ascertained that barytes extracted from the nitrate always contains a little peroxide, I conclude that in the peroxide, the quantity is double that which exists in the protoxide ; but in the neutral nitrates, the quantity of oxygen of the acid is to the quantity of oxygen of the oxide as five to
Consequently in oxygenized nitric acid, the azote will be to the oxygen in volume as one to three, I reason here on the supposition that the acid is pure; that is to say, is not a mixture of nitric and oxygenized nitric acid.
Phosphoric, arsenic, and probably boracic acid, are capable, like nitric acid, of uniting with oxygen : they retain it much . more strongly. This is the case also with the oxygenized arseniates and phosphates ; so that I am in hopes of being able to obtain these salts in a solid state.
I have not yet been able to procure oxygenized sulphuric acid. All the attempts which I have hitherto made have been indecisive.
My experiments on acetic acid have been much more conclusive. This acid dissolves the deutoxide of barium with almost as great facility as nitric acid does. No effervescence takes place, and we obtain by the process described above, an acid, which, being saturated with potash and heated, allows a great quantity of oxygen gas to escape. There is disengaged at the same time a notable quantity of carbonic acid gas. This shows that the oxygen, when assisted by heat, unites in part with the carbon, and doubtless likewise with the hydrogen of the acid.
Guided by the preceding experiments, I examined likewise the action of liquid muriatic acid on the deutoxide of barium. I expected that the result would be water, chlorine, and muriate of barytes; but the result was quite different. I obtained oxygenized muriatic acid, which I separated by means of sulphuric acid. This fact appeared to me so extraordinary, that I multiplied experiments in order to demonstrate it. One of the most decisive of these is the following :- I took a fragment of barytes, which, in order to pass to the state of deutoxide, had absorbed 12:41 centilitres of oxygen gas; I mixed it with water, and then dissolved it in diluted muriatic acid. After this, I precipitated all the barytes by means of sulphuric acid. The filtered liquid was neither precipitable by sulphuric acid, nor by nitrate of barytes. In this state I saturated it with potash, and heated it gradually till it boiled. I obtained very nearly the original volume of oxygen absorbed at first by the base. If I add that oxygenized muriatic acid leaves no residue when evaporated; that the barytes after its oxygenation requires for passing to the state of a neutral muriate the same quantity of acid as before the oxygenation; that the muriate formed exactly resembles common muriate, the existence of oxygenized muriatic acid will not, I conceive, admit of doubt.
I have obtained it only at the degree of concentration, in which it contains four times its volume of oxygen. It is a very acid,
This law holds only when the bases are pro oxides, Many bases may be mentioned, as peroxide of mercury, peroxide of cerium, in which the proportions are different, T.
colourless liquid, almost destitute of smell, and powerfully reddens tincture of turnsole. When raised to the boiling temperature, it is decomposed, and converted into oxygen and muriatic acid. When saturated with barytes, potash, or ammonia, it is decomposed still more readily, allowing a quantity of oxygen to escape. It dissolves zinc without effervescence. It does not act upon gold at the ordinary temperature, at least in the space of a few minutes. Its action on the oxide of silver is curious. These two bodies occasion as lively an effervescence as if an acid were poured upon a carbonate. The reason is, that water and a chlo. ride being formed by the reaction of the oxide and the muriatic acid on each other, the oxygen united with the acid is suddenly disengaged and assumes the gaseous form.*
The property which oxygenized muriatic acid has of being decomposed by oxide of silver, so that the oxygen becomes free, will probably put it in our power to form several other oxy: genized acids with facility. Thus with oxygenized muriatic acid and a solution of fluate of silver, we may expect to obtain oxygenized fluoric acid.
In oxygenized muriatic acid, the hydrogen and oxygen are in the proportions requisite for forming water.
Sach are the principal results which I have hitherto observed, They make us acquainted with a new class of bodies, which will, perhaps, be numerous in species. We must find them out, ascertain their properties, examine the different circumstances in which they are susceptible of being formed, we must see whether other bodies as well as acids be not capable of combining with oxygen. Thus a laborious series of experiments is chalked out, the parts of which I propose to present to the Academy in proportion as I ascertain them.
Since these observations were read, I have satisfied myself that by the process pointed out for obtaining oxygenized fluoric acid, not only this acid may be obtained, but likewise oxygenized sulphuric acid. Indeed it will be easy to obtain in that way all the acids susceptible of being oxygenized.
Oxygenized fuoric acid does not let go its oxygen at a boiling temperature; but oxygenized sulphurio acid lets it go easily. I have ascertained likewise that oxygenized nitric and
muriatic acids may be combined with new doses of oxygen. Probably the other acids are in the same case. To obtain these new com pounds, it is sufficient to treat the oxygenized acid with the deutoxide of barium, as above described; for example, to superoxygenize oxygenized muriatic acid, this acid is saturated with deutoxide of barium. The barytes is precipitated by sulphuric The discovery of this new compound seems to set the controversy respecting
Prof. Berzelius, and those other gentlemen who maintain the old doctrine, will pow be able to satisfy themselves that chlorine and oxygenized muriatic acid are two distinct substances.-T.
the nature of chlorine at rest.