In an experiment on the decomposition of water by the basis of soda, the mercury in the barometer standing at 30.4 inches, and in the thermometer at 52° Fahrenheit, the volume of hydrogen gas evolved by the action of .054 grains of basis equalled that of 326 grains of quicksilver. Now this at the mean temperature and pressure would require for its conversion into water, 0172 of oxygen, and ∙054 + 0172 0712: 054 100: 76 nearly; and according to these indications, 100 parts of soda consist of nearly 76 basis, and 24 oxygen.

In another experiment made with very great care, 052 of the basis of soda were used; the mercury in the barometer was at 29.9 inches, and that in the thermometer at 58° Fahrenheit. The volume of hydrogen evolved was equal to that of 302 grains of mercury; which would demand for its saturation by combustion, at the mean temperature and pressure, 01549 grains of oxygen; and 100 parts of soda, according to this proportion, would consist nearly of 77 basis, and 23 oxygen.

The experiments which have been just detailed, are those in which the largest quantities of materials were employed; I have compared their results, however, with the results of several others, in which the decomposition of water was performed with great care, but in which the proportion of the bases was still more minute: the largest quantity of oxygen indicated by these experiments was, for potash 17, and for soda 26 parts in 100, and the smallest 13, and 19; and comparing all the estimations, it will probably be a good approximation to the truth, to consider potash as composed of about six parts basis and one of oxygen; and soda, as consisting of seven basis and two oxygen.

VII. Some general Observations on the Relations of the Bases of Potash and Soda to other Bodies.

Should the bases of potash and soda be called metals? The greater number of philosophical persons to whom this question has been put, have answered in the affirmative. They agree with metals in opacity, lustre, malleability, con

ducting

ducting powers as to heat and electricity, and in their qualities of chemical combination.

Their low specific gravity does not appear a sufficient reason for making them a new class; for amongst the metals themselves there are remarkable differences in this respect, platina being nearly four times as heavy as tellurium *; and in the philosophical division of the classes of bodies, the analogy between the greater number of properties must always be the foundation of arrangement.

On this idea, in naming the bases of potash and soda, it will be proper to adopt the termination which, by common consent, has been applied to other newly discovered metals, and which, though originally Latin, is now naturalized in our language.

Potasium and sodium are the names by which I have ventured to call the two new substances: and whatever changes of theory, with regard to the composition of bodies, may hereafter take place, these terms can scarcely express an error; for they may be considered as implying simply the metals produced from potash and soda. I have consulted with many of the most eminent scientific persons in this country, upon the methods of derivation, and the one I have adopted has been the one most generally approved. It is perhaps more significant than elegant. But it was not possible to found names upon specific properties not common to both; and though a name for the basis of soda might have been borrowed from the Greek, yet an analogous one could not have been applied to that of potash, for the antients do not seem to have distinguished between the two alkalis.

The more caution is necessary in avoiding any theoretical expression in the terms, because the new electro-chemical phænomena that are daily becoming disclosed, seem di

Tellurium is not much more than six times as heavy as the basis of soda. There is great reason to believe that bodies of a similar chemical nature to the bases of potash and soda will be found of intermediate specific gravities between them and the lightest of the common metals. Of this subject I shall treat again in the text in some of the following pages.

stinctly

stinctly to show that the mature time for a complete generalization of chemical facts is yet far distant; and though, in the explanations of the various results of experiments that have been detailed, the antiphlogistic solution of the phanomena has been uniformly adopted, yet the motive for employing it has been rather a sense of its beauty and precision, than a conviction of its permanency and truth.

The discovery of the agencies of the gases destroyed the hypothesis of Stahl. The knowledge of the powers and effects of the ethereal substances may at a future time possibly act a similar part with regard to the more refined and ingenious hypothesis of Lavoisier; but in the present state of our knowledge, it appears the best approximation that has been made to a perfect logic of chemistry.

Whatever future changes may take place in theory, there seems however every reason to believe that the metallic bases of the alkalis, and the common metals, will stand in the same arrangement of substances; and as yet we have no good reasons for assuming the compound nature of this class of bodies *.

The experiments in which it is said that alkalis, metallic oxides, and earths may be formed from air and water alone, in processes of vegetation, have been always made in an inconclusive manner t; for distilled water, as I have endeavoured

A phlogistic chemical theory might certainly be defended, on the idea that the metals are compounds of certain unknown bases with the same matter as that existing in hydrogen; and the metallic oxides, alkalis and acids compounds of the same bases with water ;-but in this theory more unknown principles would be assumed than in the generally received theory. It would be less elegant and less distinct. In my first experiments on the distillation of the basis of potash finding hydrogen generally produced, I was led to compare the phlogistic hypothesis with the new facts, and I found it fully ade quate to the explanation. More delicate researches however afterwards proved that in the cases when inflammable gases appeared, water, or some body in which hydrogen is admitted to exist, was present.

The explanation of Van Helmont of his fact of the production of earth in the growth of the willow, was completely overturned by the researches of Woodward. Phil. Trans. vol. xxi. p. 193.

The conclusions which M. Braconnot has very lately drawn from his in. genious experiments, Annales de Chimie, Fevrier 1807, p. 187, are rendered of little avail in consequence of the circumstances stated in the text. In the only

case

voured to show*, may contain both saline and metallic impregnations; and the free atmosphere almost constantly holds in mechanical suspension solid substances of various kinds.

In the common processes of Nature, all the products of living beings may be easily conceived to be elicited from known combinations of matter. The compounds of iron, of the alkalis, and earths, with mineral acids, generally abound in soils. From the decomposition of basaltic, porphyritic †, and granitic rocks, there is a constant supply of earthy alkaline and ferruginous materials to the surface of the earth. In the sap of all plants that have been examined, certain neutrosaline compounds, containing potash, or soda, or iron, have been found. From plants they may be supplied to animals. And the chemical tendency of organization seems to be rather to combine substances into more complicated and diversified arrangements, than to reduce them into simple elements.

case of vegetation in which the free atmosphere was excluded, the seeds grew in white sand, which is stated to have been purified by washing in muriatic acid; but such a process was insufficient to deprive it of substances which might afford carbon, or various inflammable matters. Carbonaceous matter exists in several stones which afford a whitish or grayish powder; and when in a stone the quantity of carbonate of lime is very small in proportion to the other earthy ingredients, it is scarcely acted on by acids.

* Bakerian Lecture, 1806, page 8.

† In the year 1804, for a particular purpose of geological inquiry, I made an analysis of the porcelain clay of St. Stevens, in Cornwall, which results from the decomposition of the feldspar of fine-grained granite. I could not detect in it the smallest quantity of alkali. In making some experiments on specimens of the undecompounded rock taken from beneath the surface, there were evident indications of the presence of a fixed alkali, which seemed to be potash. So that it is very probable that the decomposition depends on the operation of water and the carbonic acid of the atmosphere on the alkali forming a constituent part of the crystalline matter of the feldspar, which may disintegrate from being deprived of it.

[To be continued.]

XVIII. An

XVIII. An Account of the Application of the Gas from Coal to œconomical Purposes. By Mr. WILLIAM MURDOCH. Communicated by the Right Hon. Sir JOSEPH BANKS, Bart. K. B. P.R.S.*

THE facts and results intended to be communicated in this paper, are founded upon observations made, during the present winter, at the cotton-manufactory of Messrs. Philips and Lee at Manchester, where the light obtained by the combustion of the gas from coal is used upon a very large scale; the apparatus for its production and application having been prepared by me at the works of Messrs. Boulton, Watt, and Co., at Soho.

The whole of the rooms of this cotton-mill, which is, I believe, the most extensive in the united kingdom, as well as its counting-houses and store-rooms, and the adjacent dwelling-house of Mr. Lee, are lighted with the gas from coal. The total quantity of light used during the hours of burning, has been ascertained, by a comparison of shadows, to be about equal to the light which 2500 mould candles of six in the pound would give; each of the candles, with which the comparison was made, consuming at the rate of 4-10ths of an ounce (175 grains) of tallow per hour.

The quantity of light is necessarily liable to some variation, from the difficulty of adjusting all the flames, so as to be perfectly equal at all times; but the admirable precision and exactness with which the business of this mill is conducted, afforded as excellent an opportunity of making the comparative trials I had in view, as is perhaps likely to be ever obtained in general practice. And the experiments being made upon so large a scale, and for a considerable period of time, may, I think, be assumed as a sufficiently accurate standard for determining the advantages to be expected from the use of the gas lights under favourable cir

cumstances.

It is not my intention, in the present paper, to enter into

From Philosophical Transactions for 1808, Part I.
H

Vol. 32. No. 126. Nov. 1808.

a par