reference in the chromatic observation of stars. Considering, however, the many difficulties that beset this inquiry, it is impossible not to feel the force of Sir John Herschel's assertion, that "nothing short of a separate and independent estimation of the total amount of the red, the yellow, and the blue rays in the spectrum of each star would suffice for the resolution of the problem of astrometry in the strictness of its numerical acceptation; and this the actual state of optical science leaves us destitute of the means even of attempting with the slightest prospect of success." (P. 301.) Perhaps an approximation by instrumental means to the spectra of the brighter stars ought not to be despaired of. An instance is adduced (p. 299), in which Sir David Brewster accounts for the orange colour of the double star? Herculis by an analysis of its light.

The Story of y Virginis" is one of great interest, this being perhaps the most remarkable instance in which the components of a binary star have been shown, by the combination of theoretical calculation with observation, to be acted upon by their mutual attractions Herschel, Encke, Mädler, Smyth, Henderson, Hind and Adams, are all astronomical names that have been enlisted in the theoretical investigation of the orbit of y Virginis. But no astronomer has so diligently observed this object as Capt. Smyth. His observations extend over the twenty years commencing with 1831. In the month of January 1836 he pronounced it to be round, and in April and May of the same year saw it elongated. Sir John Herschel, in a letter from the Cape of Good Hope under the date of Feb. 27, 1886, says, "y Virginis, at this time, is to all appearance a single star." The observations that have been employed by the theoretical calculators, reach as far back as 1718. In that year Pound assigned the relative position of the two stars by allineation with a known star seen with the eye directed to the sky, while the other eye was looking through the telescope. In the years 1719 and 1722 Bradley made like observations. This mode of observing, as Sir John Herschel has shown, requires a correction for a kind of optical equation between the judgements of the two eyes. Other observations were made by Mayer, in 1756; Herschel I., în 1781 and 1803; Herschel II. and South, in 1822; Struve and South, in 1825; Herschel II. and Struve, in 1828 and 1829; Herschel II., in 1830; and Dawes, in 1830 and 1831, which brings us to the date of Capt. Smyth's observations. Subsequent to these there are observations of Dawes, Lord Wrottesley, Mr. J. Fletcher of Cockermouth, and Mr. J.F. Miller of Whitehaven.

Sir John Herschel attacked the theoretical problem in an admirable and well-known communication to the Royal Astronomical Society, inserted in vol. v. of their Memoirs. He uses measures of distance, on account of their uncertainty, only for the determination of the major axis, making the values of all the other elements depend on measures of angular position. The method is in other respects essentially graphical," the aid of the eye and the hand being brought in to guide the judgement in a case where judgement only, and not calculation, can be of any avail." The first essay gave

a periodic time of 513 years. It is, however, to be remarked that after the date (1832) of that communication, the stars went through a critical part of their relative orbit, and subsequent observations were more suited to an exact determination of the periodic time. Sir John Herschel afterwards stated the period to be short of 150 years. Mädler found 145 years, Henderson, 143. Finally, in the volume of the Cape observations, Sir John Herschel entered upon a réinvestigation of the orbit, and concludes the research with the following summary:" Comparing the orbits which seem entitled to most reliance, it appears certain that the eccentricity lies between 0.855 and 0.880, the inclination between 23° and 27°, the perihelion epoch between 1836.20, and 1836-45, and the period between 140 and 190 years." It may here be remarked that the apparent eclipse of one star by the other which was observed in 1831, was not owing to the passing of the plane of the orbit through the position of the spectator, for all the calculations concur in giving a small inclination of that plane to the surface of the celestial vault; but to an actual approach of one star to the other, for the calculations as uniformly assign a large eccentricity to the relative orbit. Such an approach must have enormously changed the thermotic relations of the two bodies to each other.

It will be an appropriate conclusion to this account to put in juxtaposition Sir John Herschel's last elements, the elements obtained by Mr. Hind exclusively from Capt. Smyth's observations, and those of Mr. Adams, which take for basis Sir John Herschel's orbit, and are formed on the principle of distribution of errors by the method of least squares.

The astronomical portion of the work concludes with a dissertation on comets, accompanied by a representation of Encke's comet, as it was seen by Professor C. Piazzi Smyth with the Hartwell Telescope, at its reappearance on the 22nd of September 1848. This comet, like Biela's and others, seems to be entirely gaseous, and of such tenuity of substance that the smallest stars are visible through it without sensible diminution of their brightness.

X. Intelligence and Miscellaneous Articles.

ON THE COMPOSITION OF HUMAN FAT. BY DR. HEINTZ.

THE

HE fatty acids procured in the form of a soft mass by the decomposition of soap prepared with human fat, were pressed as much as possible, and the residue dissolved in a third part of its weight of boiling alcohol; the mass procured by exposing this to as low a temperature as possible was again pressed, and this process repeated until no trace of oleic acid was to be found in the remaining solid acids. This mixture of solid acids was analysed by repeated precipitation with acetate of lead, and four different acids procured from it. The first of these acids, which is most readily precipitated in combination with oxide of lead, exists only in very small quantity; from about 2 lbs. of human fat only about 0-2 grm. were procured in an apparently pure state. It crystallized from the alcoholic solution in small, transparent lamina of a pearly lustre; on fusion it solidified into peculiar scale-like crystals. Its meltingpoint is at 156°, and was not raised by repeated crystallization from alcohol. Its analysis led to the formula Cs6 H36 Q4.

Heintz considers it probable that this acid is identical with the stearophanic acid discovered by Dr. Francis* in the berries of Cocculus indicus.

The second acid, which, next to that above mentioned, is most readily precipitated by oxide of lead, is called anthropic acid by Dr. Heintz. From 2 lbs. of human fat only about 1 grm. of this acid was procured. When pure it crystallizes from the alcoholic solution in beautiful broad laminæ of a pearly lustre, melts at 133°, and solidifies on cooling into beautiful shining laminar crystals. The alcoholic solutions of its alkaline salts solidify on cooling into an opaline jelly; earthy and metallic salts produce insoluble precipitates in these solutions. Dr. Heintz considers the composition of this acid as not yet placed beyond doubt; his analyses gave for the free acid the formula C34 H32 O; for the silver salt, AgO, C3+H31O3 ; for the baryta salt dried at 212°, BaO, C34 H31 03+HO.

Dr. Heintz considers it possible that this acid may prove identical with the acid procured by Luckt from the oil of Madia sativa.

*Phil. Mag. Ser. 3. vol. xxi. p. 161.

† Annalen der Chemie und Pharmacie, xxxv. 210.

The third acid is margaric acid. Heintz procured it by numerous recrystallizations of the portion of fatty acids chiefly containing it; it crystallized from alcohol in fine scale-like crystals, which solidified on fusion in shining, interwoven needles; its melting-point was exactly 140°.

Free acid.

!

Baryta salt.

Lastly, the fourth acid is palmitic acid; it is the last precipitated by acetate of lead from the boiling solution of mixed acids, and appears to be contained in the greatest proportion in human fat. It melted exactly at 143°-6, and solidified on cooling into indistinctly crystallized, apparently laminar, shining masses, of a somewhat pearly lustre. When it has a small portion of margaric acid mixed with it, it crystallizes on gradual cooling after fusion in tufts of acicular crystals. From the alcoholic solution it crystallizes in small white scales.

C32 74-85 74-88 74.95 75.00 C32 52 58 H32 12.50 12.51 12:53 12:50 H3 8.52 04 12.65 12.61 12.52 12:50 04 9.20 8.82 03 7.72 7.42

52.91 C32
8.54 H31

59-22 59-37

9.62 9.59

100-00 10000 100-00 100-00 Ag 2970 2973 Bao 2344 2362

100.00 100.00

100-00 100.00

Dr. Heintz considers the olidic acid procured by Varrentrapp*, by the action of hydrate of potash in a state of fusion upon oleic acid, to be identical with palmitic acid.

Dr. Heintz has also investigated the composition of the fluid portion of human fat. The oleate of baryta, prepared according to Gottlieb's method, contained more baryta than accords with the formula given by that chemist; Heintz obtained from 22.2 to 22-5 per cent. of baryta, and a corresponding deficiency of carbon.

By repeated boilings of this oleate of baryta in so small a portion of alcohol that there was never more than a part of the salt dissolved at each operation, the residue contained at last as much as 22-7 per cent. Æther extracted from this impure oleate of baryta a salt which contained from 27 to 28 per cent. of baryta; the remaining pure oleate of baryta gave the formula proposed by Gottlieb.t Found. Calculated.

The fluid portion of human fat consists therefore essentially of oleine, with which however a small quantity of some other fluid fat is incorporated, which is distinguished from the former in that the acid which it contains furnishes on saponification a baryta salt which is more difficult of solution in alcohol than the oleate of baryta, but on the other hand is more readily soluble in æther, and which contains much more baryta.

When human fat is exposed in the winter during a long period to a temperature about the freezing-point, the fluid fat separated from the solid parts allowed to stand until the next winter, and then again submitted for a long time to a similar low temperature, a considerable portion of solid fat will again separate; and the remaining fluid portion will again present the same phænomenon in the ensuing winter. This does not depend on a conversion of oleine into margarine; but Dr. Heintz found that this solid fat, purified by pressure and crystallization from alcohol, readily dissolved in a weak boiling solution of carbonate of soda. Thus, if human fat be left for a long time in loosely-stopped vessels, a gradual decomposition of the glycerine will occur and the fatty acids of the fat be set free; these are more difficult of solution in the fluid portion than the undecomposed fat, and occasion this repeated separation.—Annalen der Chemie und Pharmacie, lxxx. 297.

NEW ARRANGEMENT OF THE VOLTAIC PILE.

BY M. FABRE DE LAGRANGE.

I have found a means of rendering the current of the voltaic pile perfectly constant and invariable, even for weeks or months, of whatever metals the electrodes may be formed, and whether they be set in action by two liquids, as in the combination of Bunsen, or by one, as in that of Volta. This continuity of electric action is obtained in the same way that we obtain the continuity of the calorific action of a stove, which is furnished below with a grating to let the ashes fall, whilst we continually add fuel at the top.

The method which I employ is simple, and fulfills all the conditions which can render it practicable in an industrial point of viewinstead of increasing the expense it diminishes it.

Let us first see the disposition of a single pair with one liquid. Take vessel with a hole in the centre of the bottom, such as a flower-pot, and round the hole let one end of a cylindrical diaphragm of cloth be attached by cement to the bottom of the pot. The axis of the hollow cloth cylinder when erect will coincide with the axis of the vessel, and its height is somewhat less than the walls of the latter. Within the diaphragm is placed a stick of very hard coke, such as is found in the gas-retorts, surrounded by small grains of the same coke, and round the diaphragm a cylinder of amalgamated zinc and some acidulated water, furnished drop by drop from a reservoir above.

Let us now unite the two poles by a conducting wire, and see what takes place in the interior of the apparatus. The acidulated water, which continues to drop into the vessel, will pass in part over the margin of the cloth diaphragm on to the grains of coke, which