diameter is easily spread over a surface of a quarter of an inch, and this property does not diminish when it is cooled to 32° Fahrenheit. It conducts electricity and heat in a similar manner to the basis of potash; and small globules of it inflame by the voltaic electrical spark, and burn with bright explosions. Its specific gravity is less than that of water. It swims in oil of sassafras of 1.096, water being 1, and sinks in naphtha of specific gravity .861. This circumstance enabled me to ascertain the point with precision. I mixed together oil of sassafras and naphtha, which combine very perfectly, observing the proportions till I had composed a fluid, in which it remained at rest above or below; and this fluid consisted of nearly twelve parts naphtha and five of oil of sassafras, which gives a specific gravity to that of water, nearly as nine to ten, or, more accurately, as 9348 to 1. The basis of soda has a much higher point of fusion than the basis of potash; its parts begin to lose their cohesion at about 120° Fahrenheit, and it is a perfect fluid at about 180°, so that it readily fuses under boiling naphtha. I have not yet been able to ascertain at what degree of heat it is volatile; but it remains fixed in a state of ignition at the point of fusion of plate glass. The chemical phenomena produced by the basis of soda are analogous to those produced by the basis of potash; but with such characteristic differences as might be well expected. * Globules may be easily made to adhere and form, one mass by strong pressure: so that the property of welding, which belongs to iron and platina at a white beat only, is possessed by this substance at common temperatures. When -When the basis of soda is exposed to the atmosphere, it immediately tarnishes, and by degrees becomes. covered with a white crust, which deliquesces much more slowly than the substance which forms on the basis of potash. It proves, on minute examination, to be pure soda.. The basis of soda combines with oxygen slowly, and without luminous appearance at all common tempera tures; and when heated this combination becomes more rapid; but no light is emitted till it has acquired a temperature nearly that of ignition. The flame that it produces in oxygen gas is white, and it sends forth bright sparks, occasioning a very beau tiful effect; in common air, it burns with light of the colour of that produced during the combustion of charcoal, but much brighter. The basis of soda when heated in hydrogen seemed to have no action upon it. When introduced into oxymuriatic acid gas, it burnt vividly with numerous scintillations of a bright red colour. Saline matter was formed in this combustion, which, as might have been expected, proved to be muriate of soda. Its operation upon water offers most satisfactory evidence of its nature. When thrown upon this fluid, it produces a violent effervescence, with a loud hissing noise; it combines with the oxygen of the water to form soda, which is dissolved, and its hydrogen is disengaged. In this operation there is no luminous appearance; and it seems probable that even in the nascent state bydogen is incapable of combining with it *. * The more volatile metals only seem capable of uniting with hydrogen; à circumstance presenting an analogy. VOL. XIII. SECOND SERIES. A a When When the basis of soda is thrown into hot water, the decomposition is more violent, and in this case a few scintillations are generally observed at the surface of the fluid; but this is owing to small particles of the basis, which are thrown out of the water sufficiently heated to burn in passing through the atmosphere. When, however, a globule is brought in contact with a small particle of water, or with moistened paper, the heat produced (there being no medium to carry it off rapidly) is usually sufficient for the accension of the basis. - The basis of soda acts upon alcohol and ether precisely in a similar manner with the basis of potash. The water that they contain is decomposed; soda is rapidly formed, and hydrogen disengaged. The basis of soda, when thrown upon the strong acids, acts upon them with great energy. When nitrous acid is employed, a vivid inflammation is produced; with muriatic and sulphuric acid there is much heat generated, but no light. When plunged, by proper means, beneath the surface of the acids, it is rapidly oxygenated; soda is produced, and the other educts are similar to those generated by the action of the basis of potash. With respect to the fixed and volatile oils and naphtha in their different states, there is a perfect coincidence between the effects of the two new substances, except in the difference of the appearances of the saponaceous compounds formed; those produced by the oxydation and combination of the basis of soda being of a darker colour, and apparently less soluble. The basis of soda, in its degrees of oxydation, has precisely similar habits with the basis of potash. When - When it is fused with dry soda, in certain quantities, there is a division of oxygen between the alkali and the base; and a deep brown fluid is produced, which be cómes a dark grey solid on cooling, and which attracts oxygen from the air, or which decomposes water, and becomes soda. The same body is often formed in the analytical pro cesses of decomposition; and it is generated when the basis of soda is fused in tubes of the purest plate-glass. There is scarcely any difference in the visible pheno mena of the agencies of the basis of soda, and that of potash on sulphur, phosphorus, and the metals. It combines with sulphur in close vessels filled with the vapour of naphtha with great vividness, with light, heat, and often with explosion from the vaporization of a portion of sulphur, and the disengagement of sulphuretted hydrogen gas. The sulphuretted basis of soda is of a deep grey colour. The phosphuret has the appearance of lead, and forms phosphate of soda by exposure to air, or by combustion, The basis of soda in the quantity of one-fortieth, renders mercury a fixed solid of the colour of silver, and the combination is attended with a considerable degree of heat. It makes an alloy with tin, without changing its colour, and it acts upon lead and gold when heated. I have not examined its habitudes with any other metals, but in its state of alloy it is soon converted into soda by exposure to air, or by the action of water, which it decomposes with the evolution of hydrogen. The amalgam of mercury and the basis of soda, seems to form triple compounds with other metals. I bave A a 2 tried tried iron and platina, which I am inclined to believe remain in combination with the mercury, when it is deprived of the new substance by exposure to air. The amalgam of the basis of soda and mercury likewise combines with sulphur, and forms a triple compound of a dark grey colour. VI. On the Proportions of the peculiar Bases and Oxygen in Potash and Soda. The facility of combustion of the bases of the alkalies, and the readiness with which they decomposed water,. offered means fully adequate for determining the proportions of their ponderable constituent parts. I shall mention the general methods of the experiments, and the results obtained by the different series, which approach as near to each other as can be expected in operations performed on such small quantities of materials. For the process in oxygen gas, I employed glass tubes containing small trays made of thin leaves of silver or other noble metals, on which the substance to be burnt, after being accurately weighed or compared with a globule of mercury, equal in size*, was placed: the tube was small at one end, curved, and brought to a fine point, but suffered to remain open; and the other end was fitted to a tube communicating with a gazometer, from which the oxygen gas was introduced, for neither water nor mercury could be used for filling the apparatus. The oxygen gas was carried through the *When the globules were very small, the comparison with mer cury, which may be quickly made by means of a micrometer, was generally employed as the means of ascertaining the weight for in this case the globule could be immediately introduced into the tube, and the weight of mercury ascertained at leisure, tube |