possibly acquire a velocity from the lapping of the paddles or wheels, there being no tail race or declivity to create and keep up such a motion.

This point being established, it seems to be conclusively in favour of disposing of the wheels of a steam-boat in the form of a water-course, as represented in the plan No. 1, and longitudinal section marked No. 3, upon the accompanying plate; and with this in view, we do not hesitate to recommend to the attention of our readers the construction of the boat here alluded to, as well calculated to give much facility in the navigation and birthage of steam-boats, and to render them applicable to canal navigation, for entering harbours, and sailing in rivers, crowded with shipping, with the most perfect security; while such a degree of convenience and accommodation is afforded to passengers as must render the Stevenson Dalswinton Steam-Boat an object of very considerable importance on ferries, and on various distant passages throughout the kingdom; as, for example, upon Queensferry, Kinghorn, and Dundee, and from Leith to various ports on the coast of England, and ultimately to London. The same description of boat is well calculated for passing from Harwich to Rotterdam, from London to Ostend, from Dover to Calais, &c. &c. &c.; such boats are also well calculated to sail from Glasgow and Greenock through all the Lochs of Argyleshire, and the Crinan and Caledonian canals, to the eastern coast of Scotland; also to Belfast, Dublin, and Liverpool, and upon the great public ferries from Holyhead to Dublin, and Portpatrick to Donaghadee. Indeed on many of these passages the steam-boat has already been tried, even in its present imperfect state, with a good effect; and we despair not of seeing this noble invention so much matured that their voyages to the distant parts alluded will be made with such a degree of safety and dispatch as to render this one of the most valuable improvements connected with the insular situation of Great Britain.

Thus if our humble endeavours shall be found useful either in advancing the improvement of the steam-boat, or in tracing these inventions to their proper authors, our end and object will have been completely obtained.

Observations on the Chemical Constitution of Muriatic Acid Gas, and on some other Subjects of Chemical Theory. By John Murray, M.D. F.R.S.E. Fellow of the Royal College of Physicians of Edinburgh.

ADMITTING water to be procured from muriatic acid gas in those forms of experiment, direct or indir

hich the

agency of no other substance that can afford it, is introduced, the conclusion seems necessarily to follow, which forms the basis of one of the two systems under which the relations of oxymuriatic and muriatic acids have of late years been explained, that oxymuriatic acid is a compound of muriatic acid with oxygen; and that muriatic acid in its gaseous stater contains combined water. This doctrine, accordingly, may be maintained, and may even perhaps be just. It is not, therefore, from the consideration of any deficiency in its support that I depart from it in the following observations; but that I consider the view I have to propose as perhaps more probable, or at least as, on the whole, according better with the present state of chemical theory. In a science such as chemistry, the principles of which rest rather on probable evidence than on demonstration, it is of importance to present a subject in every point of view under which it may be surveyed; and this must serve as an apology for the speculations I have now to offer.

There are, I believe, only two arguments to which any weight is due in support of the opinion that chlorine is a simple substance, which, by combination with hydrogen, forms muriatic acid. One is drawn from the analogy resting on the general fact, sufficiently established, that acidity is, in different cases, the result of the agency of hydrogen; the other, from the analogy in the chemical relations of chlorine and iodine.bod

Sulphur forms with hydrogen a compound unequivocally acid. The compound radical of prussic acid cyanogen, discovered by the able researches of Gay-Lussac, likewise acquires acidity when its receives hydrogen. Acidity, therefore, is a property not exclusively connected with oxygen; it is also communicated by hydrogen; and when chlorine with hydrogen gas forms muriatic acid gas, the agency exerted may be considered as similar to that arising in other cases of the production of an acid from the action of hydrogen.

This is confirmed by the relations of iodine. It too forms an acid by combination with hydrogen; and the chemical agencies of iodine are in several other respects similar to those of chlorine. When the one, therefore, is considered as a simple body (and there is no absolute proof that iodine is a compound), the other is, with probability, placed in the same class and certain analogies existing between sulphur and iodine serve to connect and confirm these views. Each of them forms an acid with hydrogen; each of them also forms an acid with oxygen; but chlorine exhibits precisely the same points of resemblance with hydrogen, it forms muriatic acid oxygen, it

with

regard to forms chloric acid. Its chemical relations, with

regard to acidity, being thus similar, seem to require the same explanation to account for them.

These facts lead undoubtedly to views of chemical theory different from those which had before been established; and on

which the old doctrine with regard to the nature of muriatic and oxymuriatic acid rests. It may be well, therefore, to inquire, how far they may modify the conclusions to be drawn, admitting even that oxymuriatic acid contains oxygen, and that muriatic acid gas affords water.

When water is obtained from muriatic acid gas, it does not necessarily follow that it has pre-existed in the state of water. It is equally possible, à priori, that its elements may be present in simultaneous combination with the acid, or its radical; that -the acid is a ternary compound of a radical with oxygen and hydrogen; and that it is decomposed in those processes by which water is procured, the hydrogen, with the requisite proportion of oxygen, combining to form water; and its radical, with any excess of oxygen, remaining in union with the substance by which the change has been effected.

If this view were adopted with regard to muriatic acid, the same view might, on the same grounds, be applied to the other acids, which appear to contain water in intimate combination, and in a definite proportion. And such an acid, the radical and precise constitution of which are known, may be best adapted to illustrate the hypothesis.

Sulphuric acid affords water when it is submitted to the action of an alkaline base; and the quantity of this water appears to be definite, amounting to 185 in 100 of the strongest acid which can be procured in an insulated state; 100 parts of this acid, therefore, are considered as composed of 81.5 of real acid (consisting of 32-6 of sulphur and 48-9 of oxygen) with 18-5 of water. But if, instead of this view of its constitution, it be considered as a ternary compound of sulphur, oxygen, and hydrogen, its composition will be 32.6 of sulphur, 65.2 of oxygen, and 2-2 of hydrogen. In those processes by which -water is obtained from it; in the action, for example, of an alkaline base, and subsequent exposure to heat, the composition is subverted by the affinities exerted; the hydrogen unites with the requisite proportion of oxygen, forming water, and the remaining oxygen with the sulphur unite with the base. In the action of a metal on the acid, there is the same result; only by the attraction of the metal to oxygen, the whole of that element is retained, and the hydrogen is disengaged.

Muriatic acid gas then, according to this doctrine, is the real acid, a ternary compound of a radical (at present unknown) with oxygen and hydrogen, exactly as sulphuric acid in its highest state of concentration is the real acid, a ternary compound of sulphur, oxygen, and hydrogen. When it is submitted to an alkaline base, the action exerted causes its decomposition; its hydrogen, and part of its oxygen, combine to form water; and its radical, with its remaining oxygen, unite with the base, forming a neutral compound, analogous to what other acids of similar constitution form. When a similar result is obtained from the

action of a metal, its whole oxygen must be considered as retained, and its hydrogen is liberated.

Nitric acid in its highest state of concentration is not a definite compound of real acid with about a fourth of its weight of water, but a ternary compound of nitrogen, oxygen, and hydrogen. Phosphoric acid is a triple compound of phosphorus, oxygen, and hydrogen; and phosphorous acid is the proper binary compound of phosphorus and oxygen. The oxalic, tartaric, and other vegetable acids, are admitted to be ternary compounds of carbon, oxygen, and hydrogen; and are, therefore, in strict conformity to the doctrine now illustrated.

A relation of the elements of bodies to acidity is thus discovered different from what has hitherto been proposed. When a series of compounds exists, which have certain common characteristic properties, and when these compounds all contain a common element, we conclude with justice that these properties are derived more peculiarly from the action of this element. On this ground Lavoisier inferred, by an ample induction, that oxygen is a principle of acidity. Berthollet brought into view the conclusion that it is not exclusively so, from the examples of prussic acid and sulphuretted hydrogen. In the latter, acidity appeared to be produced by the action of hydrogen. The discovery by Gay-Lussac of the compound radical cyanogen, and its conversion into prussic acid by the addition of hydrogen, confirmed this conclusion; and the discovery of the relations of iodine still further established it. And now, if the preceding views are just, the system must be still further modified. While each of these conclusions is just to a certain extent, each of them requires to be limited in some of the cases to which they are applied; and while acidity is sometimes exclusively connected with oxygen, sometimes with hydrogen, the principle must also be admitted that it is more frequently the result of their combined operation.

There appears even sufficient reason to infer that from the united action of these elements, a higher degree of acidity is acquired than from the action of either alone. Sulphur affords a striking example of this. With hydrogen it forms a weak acid. With oxygen, it also forms an acid, which, though of superior energy, still does not display much power. With hydrogen and oxygen, it seems to receive the acidifying influence of both, and its acidity is proportionally exalted.

Nitrogen with hydrogen forms a compound altogether destitute of acidity, and possessed even of qualities the reverse. With oxygen in two definite proportions, it forms oxides; and it is doubtful, if in any proportion, it can establish with oxygen an insulated acid. But with oxygen and hydrogen in union, it forms nitric acid, a compound more permanent, and of energetic action.

Carbon with hydrogen forms compounds which retain inflam

mability without any acid quality; with oxygen, it forms first an inflammable oxide, and with a larger proportion a weak acid; but combined with both hydrogen and oxygen, in different proportions, it forms in the vegetable acids compounds having a high acidity. These acids, therefore, are not to be regarded, according to the theory of Lavoisier, as composed of a compound base of carbon and hydrogen, acidified by oxygen, but of a simple base, carbon, acidified by the joint action of oxygen and hydrogen.

Muriatic acid itself presents the same result. Oxymuriatic acid must be considered, according to this doctrine, as a compound of an unknown radical (Murion, if the term may be allowed) with oxygen, analogous in this respect to sulphurous acid, except that in the latter there is an excess of base, in the former an excess of oxygen and oxymuriatic acid, with the addition of hydrogen, forms the ternary compound muriatic acid, as sulphurous acid with the same addition forms hydrosulphuric acid, with a deposition of the excess of sulphur. There is accordingly the strictest analogy between muriatic acid and those other acids, the sulphuric, nitric, &c. which contain both oxygen and hydrogen; while there is none, as Berzelius remarked, between it and, those, such as the prussic acid or sulphuretted hydrogen, which contain merely hydrogen. This principle solves the difficulty which has always presented itself in the relation of muriatic and oxymuriatic acids on Lavoisier's theory of acidity-that the latter, though it has received an addition of oxygen, is inferior in acid power to the former. It is so precisely, as the binary sulphurous acid is one of less energy of action than the ternary hydrosulphuric acid, or as the carbonic is less powerful than the oxalic acid. The proper analogy is that of the oxymuriatic with the sulphurous acid, and the muriatic with the sulphuric; and under this point of view there is no anomaly, but strict conformity. And thus also is accounted for, what is at variance with the hypothesis of Gay-Lussac, the total want of analogy between chlorine and sulphur, which he classes together, except in the single circumstance of acidity being communicated to both by hydrogen; while there exists a close analogy between sulphurous acid and oxymuriatic acid in their most essential properties their gaseous form, their specific gravity, their suffocating odour, their power of destroying vegetable colours, their solubility in water, their remaining combined with it in congelation, their acidity, their combining weights, and their being attracted to the positive pole of the voltaic series; and any deviation from this analogy evidently arises from the excess of oxygen in oxymuriatic acid.*

11

*It is curious with regard to the most important of these analogies, that of the equivalent or combining weights, that oxymuriatic acid stands next to sulphurous acid ; the former in Dr. Wollaston's scale being 44, while the latter will be found to be 40. The acidity of oxymuriatic acid is fully established by the most unequiVOL. XIII. N° IV.

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