sp. gr. 1.5, for their decomposition, and this determination has been noticed by Dr. Wollaston, as agreeing very closely with his views of the composition of liquid nitric acid. In order to try how much nitrate of lime would be obtained from the decomposition of a given weight of the carbonate, I put 150 grains of double refracting spar into a quantity of nitric acid, insufficient to decompose the whole of it; the platina crucible containing the solution of nitrate of lime, and the undecomposed carbonate, was heated till all the water was dissipated; on weighing, I obtained 243.2 grains. After dissolving the nitrate of lime in water, I found 3.4 of carbonate unacted upon; if then we subtract 3.4 from 150, the quantity of carbonate of lime originally used, and also from 243.2 the weight of the nitrate and carbonate of lime, it will appear that 146.6 of carbonate, were converted into 239.8 of nitrate of lime.

The experiments which I have now mentioned, show that 63 of carbonate of lime are decomposable by 90.23 of nitric acid 1.5, and that 103.05 of nitrate of lime result from their action, it will be seen by the scale, that 63 of carbonate of lime contain 35.46 of lime, which deducted from 103.05 the nitrate of lime give 67.59, as the dry nitric acid contained in 90.23 of liquid acid of 1,5, or it consists of 74.91 acid + 25.09 water, a determination in which it will be seen, that the acid differs only about part from the quantity stated by Dr. Wollaston.

With respect then to the composition of liquid, as well as of dry nitric acid, I conclude in direct opposition to Dr. Ure, that the subject is neither obscure nor mysterious; on the contrary, it appears to me, that the eminent philosophers, whose results he quotes to condemn, or whose conclusions he confirms or copies, have effected all the certainty which can be derived, from the "best directed efforts of modern science."

ART. XIX. Proceedings of the Royal Society of
London.

Thursday, Jan. 8th, and 15th. THESE meetings of the Society were occupied by the reading of a paper presented by Dr. Brewster, relating to the laws of double refraction in regularly crystalized bodies.

Jan. 22. A paper was communicated by Sir Everard Home, containing additional facts respecting certain fossil remains, formerly described by the author in the Philosophical Transactions. The analogy between the animal alluded to and cartilaginous fishes, is destroyed by the examination of the bones of the sternum, which much resemble those of the Ornithorynchus Paradoxus. Sir Everard proved that the fossil animal lived in water by the form of its vertebra; while from the shape of its chest it was shown to have breathed air. In concluding his observations upon these subjects, Sir Everard remarked upon the interest of discovering in this country fossil bones which bear an analogy to those of an animal of New Holland of so peculiar a character as the Ornithorynchus.

Jan. 29. An extremely curious and important paper was read to the Society by Captain Kater, giving an account of his experiments for determining the length of the pendulum vibrating seconds in the latitude of London. We have already hinted that the President and Council adjudged the Copley Medal to Captain Kater for this important inquiry; after showing the objections to all methods hitherto practised for accurately ascertaining the length of the seconds pendulum, Captain Kater detailed with great perspicuity the mode of proceeding which he had successfully adopted, and which was founded on the reciprocity of the centres of suspension and oscillation. Captain Kater then describes the various corrections for temperature, pressure, and height above the sea, and having shown the advantages of his different methods, concludes, that the length of the pendulum vibrating seconds in vacuo at the level of the sea, measured at the temperature of 62° Fahr. and the latitude of

the place of observation deduced from the data contained in the Trigonometrical Survey, being 51° 31' 8" 4 North, is, By Sir George Shuckburgh's Standard,

By General Roy's Scale,

By Bird's Parliamentary Standard,

39,13860 inches.

39,13717 do.

39,13843. do.

Feb. 5th. Capt. Kater communicated a paper on the length of the French metre, estimated in parts of the English standard. For the purpose of ascertaining this important point, two metres were sent from Paris-the one is a bar of platinum of the exact length, and called the metre à bouts—the other is a somewhat longer bar of the same metal upon which the length of the metre is shown by two very fine lines-it is called a metre à traits. The mean result of several very delicate experiments gave the length of the French metre = 39,37071 inches of Sir George Shuckburgh's scale-or 39,37062 inches of Bird's Parliamentary standard.

At the same meeting a paper was read by Thomas Andrew Knight, Esq. on the office of the heart-wood of trees. Mr. Knight's object in this paper was to show that the heart-wood of trees is a winter reservoir for the organizable matter required for their germination in the spring, and that the presence or absence of this reservoir is connected with the annual, biennial, and perennial duration of plants. The annual having no such reservoir, is entirely exhausted in forming its flowers and seeds. A biennial fills its reservoir one season, and exhausts it the next, and in the tree, part of the sap descends to form roots, and part ascends to produce buds, and it also forms a new annual layer of bark. Mr. Knight's paper also contained some statical experiments on the quantity of water contained in the alburnum of different trees at different seasons of the year.

Feb. 12. A paper by Dr. Marshall Hall was read on the combined agencies of oxygen and water in producing the oxidizement of iron. Dr. Hall has shown in this paper, that iron is incapable of decomposing water at common temperatures, and that it becomes rusty or oxidized when exposed to common water, as is generally stated; but from the decomposition of the

air in water he also shows that nitrogen alone is evolved and no hydrogen and that when water is deprived of atmospheric air, or oxygen, iron retains a clear and bright surface though exposed for many months to its action.

At the same meeting Sir H. Davy read some remarks on the fallacy of the experiments, in which water is said to have been formed by the decomposition of chlorine.

These experiments go to prove that the oxygen required to form the water obtained in the experiment alluded to, is derived, not as has erroneously been asserted, from the chlorine, but from other sources, which had eluded the vigilance of the experimentalists.

Feb. 19th. A letter from George Rennie, Esq. to Dr. Young, was read, containing an account of some experiments on the strength of materials. Mr. Rennie shows in this communication, that the strength of cast iron is extremely various according to the circumstances under which it has been cast. Thus vertical castings are stronger than horizontal, &c. Observations are annexed on the relative strength of woods, stones, and other building materials.

Feb. 26th. A paper was presented by Thomas Knight Esq. containing a solution of an analytical problem; and another by J. F. W. Herschell, Esq., "on circulating functions, and on the integrations of a class of equations of finite differences into which they enter as coefficients "

Mar. 5. A paper was read to the Society on the Parallax of certain fixed stars by the Rev. John Brinkley, D. D. F. R. S. ; and at the same meeting, Sir Everard Home cummunicated some additions to his Croonian Lecture. (See page 362, Vol. 4, of this Journal.) Captain Kater having put the author in possession of more accurate measurements of the globules of the blood than those formerly given, Sir Everard now stated these to the Society-and is induced to consider the diameter of a globule of the blood as of an inch instead of zoo.

=

This paper also contains many additional experiments and observations relative to the formation of tubuli by the extrication of air during the coagulation of blood.-The author also

announces that similar appearances are obtained during the exsiccation of pus, and applies this circumstance to the expla nation of the formation of granulations in sores.

Mar. 12. A letter from B. Bevan, Esq. to the President, was read, relative to the discovery of some fossils in Leicestershire and Northamptonshire; and also a letter from Dr. Fischer of Moscow, containing observations on the anatomy of spiderswith some illustrative drawings.

At this meeting, the Society proceeded to ballot for foreign members, and the following Gentlemen were announced by the President as duly elected into the Society.

Mr. Nathaniel Bowditch, of Salem, of the State of Massa

chusetts.

Messrs. G. F. C. M. de Prony,

Francis Arago,

S. D. Poisson,

J. P. Haüy,

of Paris.

The Society then adjourned for the Easter Vacation.

ART. XX. Proceedings of the Royal Society of Edinburgh.

1818. January 5. THE continuation of Dr. Murray's Paper

on muriatic acid gas was read. The conclusion drawn from the experiments before, and now detailed, is that chlorine is not a simple body, but the idea of its being a compound of muriatic gas and oxygen is not adopted. Dr. Murray then offered a theory in explanation not only of the nature of muriatic acid, but of acids and alkalies in general. Both oxygen and hydrogen were supposed to have the power of conferring acidity and alkalinity on the bodies with which they combine, and that when both combine at once with a body, the properties which they impress are proportionately increased. Chlorine therefore is conceived to be a compound of an unknown base with oxygen; muriatic acid a combination of chlorine with hydrogen,