membranous capsule, each of which produces from 3 to 8 young, which, on escaping from the egg, are of various sizes, and very

active.

But the most singular part of the history of these animals is, that they not only perpetuate their species as above described, but also by a natural division of their body into two portions, the head part reproducing a tail, and the tail a head in about fourteen days. These appearances are represented in annexed drawings, and several experiments are detailed in further illustration of their reproduction, showing that a perfect animal is producible.

Some Experiments and Researches on the Saline Contents of Seawater, undertaken with a view to correct and improve its Chemical Analysis. By Alexander Marcet, M.D. F.R.S. Honorary Professor of Chemistry at Geneva. Read June 27, 1822. [Phil. Trans. 1822, p. 448.]

At the commencement of this paper Dr. Marcet, after adverting to the conclusions at which he arrived in some former researches communicated to this Society, notices the extraordinary assertions of Rouelle and of Proust respecting the existence of mercury in sea water. By a very careful examination, however, of bay salt, he was unable to detect the smallest trace of that metal; nor did he find it in a sample of Sel de Gabelle obtained from Calais for the purpose of examination.

Dr. Marcet next examined sea water, with a view of ascertaining whether any nitrates are present in it: with this view he added sulphuric acid and gold leaf to the concentrated bittern, and boiled the mixture, but the metal was not in the least acted on; when, however, the smallest quantity of nitre was added, the gold was instantly dissolved. Hence the absence of nitric salts in sea water may be inferred.

In examining some of the same bittern for earthy and metallic salts, the author found that neither alkalies nor their carbonates throw down anything but magnesia, and that no muriate of lime appears in any case to be present. Selenite and carbonate of lime were, however, found in the matters deposited during the first evaporation of the transparent and pure sea water.

When sea water is evaporated to dryness, and the residue submitted to distillation at a red heat, Dr. Marcet found that a portion of sal-ammoniac sublimed. Lastly, he observes, that no sulphate of soda is discoverable in sea water, but that it affords, on evaporation along with other salts, certain rhombic crystals, which are triple sulphate of potash and magnesia.

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On the Ultimate Analysis of Vegetable and Animal Substances. By Andrew Ure, M.D. F.R.S. Read June 27, 1822. [Phil. Trans. 1822, p. 457.]

Dr. Ure commences this paper by adverting to the fallacies to which the modes of analysing organic substances hitherto practised are subject; and in detailing the peculiar methods adopted in his own researches, he shows the means of obviating them, and of diminishing the various sources of inaccuracy to which these complicated processes of analytical chemistry are necessarily more or less liable. Where oxide of copper is used, its hygrometric quality has generally been overlooked, or not duly allowed for; and the animal and vegetable substances have not in general been exposed to any process of desiccation sufficiently exact or uniform; the author therefore always used the oxide of copper in some known or ascertained degree of humidity; and he dried the organic bodies in the air-pump vacuum, aided by the absorbent powers of a surface of sulphuric acid in the apparatus, and with precautions which he fully describes. He then details the best means of applying heat for the decomposition of organic substances, and describes a drawing representing the construction of his furnace, and other implements. Lastly, he points out the method of examining the results and products, and gives in detail the analysis of sulphuric ether, as illustrating the mode of computing the relations of the constituents, while the results of the other analyses are, for the sake of brevity, thrown into a tabular form. Dr. Ure concludes his paper with some general remarks on the analytical details. In respect to sugar, he observes, that on comparing pure crystalline sugar with diabetic sugar, the latter exhibits a notable excess of oxygen; and he considers weak sugars (as the refiners call them), in general, to exhibit the same peculiarity.

In applying the atomic theory to his experimental results, the author enlarges on the different views which may be taken of the ultimate constitution of a variety of organic products, and enters at considerable length into details relating to the vegetable acids, with a view of determining with exactness their prime equivalents, and the relative proportions of combined water which they contain in their crystalline states.

The Croonian Lecture. Microscopical Observations on the Suspension of the Muscular Motions of the Vibrio tritici. By Francis Bauer, Esq. F.R.S. F.L.S. and H.S. Read December 5, 1822. [Phil. Trans. 1823, p. 1.]

The Vibrio tritici is a small worm which infects wheat, being the immediate cause of that destructive disease called Ear Cockle, or Purples. Upon examining the grains thus diseased, the author found. them to be the unimpregnated germens, containing masses of a white and apparently gluey mucus, which might be removed in the shape of a firm ball, and which, when immersed in water, and viewed

through the microscope, displayed hundreds of minute worms in lively motion. When these worms had become perfectly dry, and apparently entirely lifeless, they again recovered upon being moistened with a drop of water, and were as lively as before.

To determine the origin of these animals, Mr. Bauer undertook a series of experiments, which convinced him that the spawn or eggs were conveyed into the cavities of the germens by the circulating sap. In these experiments he inserted some of the worms into sound grains of wheat, suffered them to germinate, and found the worms in different stages of their growth in the stalk, and ultimately in the germens.

The largest of these worms was one fourth of an inch long, and one eightieth of an inch in diameter; their head is armed with a moveable proboscis, and the tail ends in a claw-like point; at a small distance from which, on the inferior side, is an orifice, from which they discharge their eggs in strings of five or six, adhering to each other. Each egg is about th of an inch long, and th, or oth in diameter; and if attentively examined, they are transparent enough to allow of the young worm being seen within, which, in about an hour and a half after the egg is laid, extricates itself. These worms exhibit no external distinctions of sex, and the author considers them to be hermaphrodites.

The first specimens of these worms which Mr. Bauer examined, were from grains twelve months old, and consequently perfectly dry. He. however, also succeeded in recovering them by immersion in water, from wheat which had been kept five years and eight months; but the longer the specimens were kept, the longer were the worms obliged to be immersed in water, to enable them to recover their muscular motions. The longest period of its suspension which he had observed, was six years and one month; after that time they seemed perfectly dead.

Alternately moistened and dried in a watch-glass, these worms might be preserved alive for several weeks; and if kept continually moist, they remained alive for three months; but if dried at the end of that period, they do not again recover, but become quite straight, and remain unaltered in the water for more than fourteen months, when they gradually decay. Their extraordinary preservation, and these various circumstances, Mr. Bauer refers to the mucous-like water in which they are enveloped, and which appears to be of an oily na

ture.

The author concludes this paper with an abstract of the description of these worms given by other writers, and of their opinions respecting their origin.

On Metallic Titanium. By W. H. Wollaston, M.D. V.P.R.S. Read December 12, 1822. [Phil. Trans. 1823, p. 17.]

Small cubic crystals are occasionally met with in the slag of iron furnaces, which, from being imbedded in sulphuret of iron, have been

mistaken for pyrites. Upon subjecting them, however, to more rigid examination than they had previously received, Dr. Wollaston ascertained them to be titanium in its metallic state. He found them not only harder than pyrites, but so hard as to scratch glass, and even agate. They are neither acted upon by nitric, sulphuric, nor muriatic acids; nor are they dissolved by nitro-muriatic acid. They are infusible before the blowpipe, but become superficially oxidized, and borax restores the cleanliness of their surface, by dissolving the oxide. By nitre they are rapidly oxidized; and by combining its action with that of borax, they may be entirely dissolved. The fused mass is soluble in muriatic acid; and from this solution the alkalies precipitate a white oxide, insoluble in pure and carbonated alkalies. When evaporated, the excess of muriatic acid may be driven off, and a soluble muriate remains, in a state favourable for exhibiting the leading properties of titanium. Infusion of galls produces in this solution the characteristic red precipitate; prussiate of potash occasions one of similar colour, which differs from prussiate of copper by inclining to orange instead of purple, while prussiate of uranium is rather brown than red.

Although the crystals are imbedded in sulphuret of iron, Dr. Wollaston found in them neither iron nor sulphur. That they are in the metallic state, is proved by the perfection with which they conduct a feeble degree of electricity. They did not unite with tin, lead, silver, or copper. From their extreme infusibility, Dr. Wollaston thinks that they have not been formed by crystallization in cooling from a state of fusion, but have received their successive increments by reduction of the oxide dissolved in the slag around them,-a mode of formation to which we must have recourse for conceiving rightly the formation in nature of many other metallic crystals.

On the Difference of Structure between the Human Membrana Tympani and that of the Elephant. By Sir Everard Home, Bart. V.P.Ř.S. Read December 12, 1822. [Phil. Trans. 1823, p. 23.]

In an elephant three weeks old, the membrana tympani was of an oval form, 14 inch long, and 14 broad. The muscular fibres lie upon its inner surface, and terminate by an attachment to the point and two sides of the malleus, so that one portion of the fibres is short, and the other more than double their length. From this structure the elephant cannot adapt its ear to musical sounds in the same manner the human ear does; but in Sir Everard's opinion, it is enabled by the long fibres to hear sounds at a great distance. In regard to musical sounds, high notes scarcely excite its attention, but it listens to the lower ones with apparent satisfaction. In neat cattle, and in the deer, the membrana tympani is oval, and the structure approximates to that in the elephant. In the horse, the hare,

and the cat, the handle of the malleus lies in the middle line, so that the fibres on the two sides are equal, and the organ appears similarly constructed in the whole of the feline tribe.

Corrections applied to the Great Meridional Arc, extending from Lutitude 8° 9′ 38"-39 to Latitude 18° 3′ 23′′-64, to reduce it to the Parliamentary Standard. By Lieutenant Colonel W. Lambton, F.R.S. and Corresponding Member of the Royal Academy of Sciences at Paris. Read January 9, 1823. [Phil. Trans. 1823, p. 27.]

It appears from the investigations detailed in this paper, that with respect to a measurement on the meridian, the degree depending on Colonel Lambton's brass scale must be multiplied by the fraction 000018, and the product subtracted from the measure given by the scale to reduce it to the present parliamentary standard; and that the degree depending on Ramsden's bar must be multiplied by 00007, and the product added to the measure given by the scale to reduce it to the standard.

On the Changes which have taken place in the Declination of some of the principal fixed Stars. By John Pond, Esq. Astronomer Royal, F.R.S. Read April 18, 1822. [Phil. Trans. 1823, p. 34.]

The objects of this communication are chiefly two; the first is to restore a greater degree of confidence in the results of the late observations made with the mural circle at Greenwich, which now appear to have been subjected to a very small error only, arising from some temporary causes now very effectually removed; and the second to point out a want of uniformity in the proper motions of almost all the stars, which is of such a nature as to indicate a slow change of place towards the south in almost every instance, with the exception of y Ursæ majoris, 6 Ursæ minoris, and 6 Cephei only. The greatest deviation is found in three very bright stars, Capella, Procyon, and Sirius. The proper motion of each of these is southward; hence these proper motions are accelerated, while that of Arcturus, on the contrary, may be considered as uniform.

The author observes, that though the number of stars which have proper motions northwards is nearly equal to those of which the proper motion is southward, yet the joint magnitude of the motions southward exceeds that of the motions directed northwards nearly in the proportion of 4 to 1.

It was not till after February, 1821, that the mural circle became completely out of repair; its present perfection has been verified by means of observations made with an artificial horizon of mercury protected by wooden boxes, of different sizes and figures according to the different altitudes of the stars: at the same time, Mr. Pond observes, that for very delicate purposes it would be improper to place implicit confidence in the observations of declination made in the course of the year 1820.