surface of the water will, therefore, in calm and clear weather, and in temperatures above 45° Fahr., be warmer than that of the contiguous land; and, consequently, the air above the land will be cooler than that above the water. When the cold air, therefore, from the land mixes with that above the water, both of them containing their due proportion of aqueous vapour, a mist or fog must be the result.

On the Geology of Plymouth and its Vicinity. By
Mr. WHIDBEY.- [1821.]

THE mountain limestone of Plymouth lies directly upon clay-slate, and is remarkably scanty in organic remains; it includes certain caverns, perfectly insulated, some of which are incrusted with stalactite, and present nothing remarkable. In others, the author has discovered certain fossil bones in caves without any stalactical incrustation, having only a little dry clay at the bottom. "The cavity was entirely surrounded by compact limestone rock, about eight feet above high water mark, 55 feet below the surface of the rock, 174 yards from the original face of the quarries, and about 120 yards in that direction from the spot where the former bones were found in 1816." The bones are those of the rhinoceros, the bear, and an animal of the deer kind, and of another animal of the size of the bear.

The Croonian Lecture; or, Microscopical Observations on the Brain and Nerves. By Sir EVERARD HOME, Bart. THIS paper shows that the materials of which the brain and nerves are composed exist in the blood. Bauer examined the optic nerve, and found it to consist of many bundles of fine fibres, formed of very minute globules united by a soluble transparent jelly. "By the discovery of this transparent substance," says Sir Everard, "we become acquainted with the nature of the medullary structure of the nerves, and can form some idea of their action, which till now I confess myself to have been totally unacquainted with. The nerves as well as the retina are composed of this newly discovered transparent substance, which is very elastic and soluble in water, and globules of 300 and parts of an inch in diameter. Its transparency and solubility account for its having remained concealed; and were it not coagulable, in which state it becomes opaque, its existence might even now

be considered as equivocal." The brain is also, according to Bauer, a conglomerate of globules and soluble mucus, the former arranged into fibres and bundles, held together by the latter. It is pervaded by blood-vessels, but the arteries never anastomose, and the veins, which are very small, are supplied with valves, and perform the office of lymphatics, carrying the absorbed matter into the superior longitudinal sinus.

"That the cortical part of the brain is the seat of memory, is an opinion," says Sir Everard, "which I have long entertained, from finding that any continued undue pressure upon the upper anterior part of the brain entirely destroys memory, and a less degree materially diminishes it. Pressure upon the dura mater, where the skull has been trepanned, puts a temporary stop to all sense, which is restored the moment that pressure is removed; and the organ appears to receive no injury from repeated experiments of this kind having been made. In hydrocephalus, when the fluid is in large quantity, and there only remains the cortical part of the brain and the pons Varolii connecting it to the cerebellum, all the functions go on, and the memory can retain passages of poetry, so as to say them by heart; but a violent shake of the head produces instant insensibility. Pressure in a slight degree produced in one case complete derangement, with violent excess of passion, both of which went off upon removing, by the crown of the trepan, the depressed bone."

And adverting to the abundance and office of the transparent mucus, Sir Everard says, "There can be no doubt that the communication of sensation and volition more or less depend upon it." Indeed, it is evident that those functions cannot be ascribed to any individual component of the brain and nerves, but belong to them as entire structures. The remainder of this part of the lecture is taken in up attempting to show that the above-mentioned mucus exists ready formed in the blood, and that it is the medium "by which the colouring matter is attached to the surface of the red globules;" and that fat may exist in the blood. The next portion of this lecture is devoted to the provision for carrying off the fluids taken into the stomach, whenever the quantity or quality interferes with the process of digestion. "To do this by the route of the thoracic duct was not only too circuitous to correspond with the general simplicity of the operations of nature, but was mixing these heterogeneous liquids in too crude a state, with the general circulation of the blood. That there was some unusual mode of conveying fluids from the stomach to the urinary bladder, I have upon

a former occasion established, since they arrived there when both the pylorus and thoracic duct were tied up, and the spleen was removed out of the body; but till the fact of valvular vessels supplying the office of absorbents was ascertained, any opinion respecting the route of fluids from the stomach must continue to be entirely hypothetical."

Sir Everard then demonstrates the existence of such vessels, and describes their situation and appearance, by engravings of Bauer's drawings.

"To show the course of the absorbed fluids, as well as to give a clear idea of every thing connected with so important a discovery, a drawing of the spleen, the vas breve, and cardiac portion of the stomach, is annexed; and as the trunk of the splenic vein forms one of the trunks of the vena portæ, the liquids are directly carried to the liver, forming a part of the materials employed in producing the bile; the remainder only returning by the vena cava to the heart.

"This additional quantity of liquids passing along the splenic vein accounts for its being five times the size of the artery, as well as for the blood in that vein having a greater proportion of serura than the blood in any other, which has been long asserted, and which I found by actual experiments to be the case; but being unable to account for it, as I can now, I was willing to admit that the mode of measuring might be erroneous."

The spleen is then shown to consist of blood-vessels, between which there is no cellular membrane, the interstices being filled with serum, and with the colouring matter of the blood from the lateral orifice in the veins, when these vessels are distended; which serum is afterwards removed by the absorbents belonging to the organ, and carried into the thoracic duct by a very large absorbent trunk; so that from this mechanism "the spleen appears to be a reservoir for the superabundant serum, lymph globules, soluble mucus, and colouring matter, carried into the circulation immediately after the process of digestion is completed."

The Bakerian Lecture, on the Composition and Analysis of the inflammable gaseous Compounds resulting from the destructive Distillation of Coal and Oil; with some Remarks on their relative heating and illuminating Powers. WILLIAM THOMAS BRANDE, Esq. — [1821.]

By

THE gases used in the following experiments, except where it is otherwise expressly stated, were those employed

for the common purposes of illumination; the coal gas being that supplied from the Company's works in Westminster, and the oil gas furnished by the decomposition of common whale oil, in an apparatus erected for that purpose at Apothecaries' Hall.

My first object, in the examination of coal gas, was to ascertain its specific gravity; and the first that I examined was so low as .4430, and purified in the usual way, by condensation in cold vessels, and passing through lime water, it was as high as .4940.

Having filled the gasometer with pure olefiant gas, it was allowed to issue from a brass jet, having a single perforation of of an inch diameter, under a pressure of a half inch column of water; it was then inflamed, and regulated by means of a stop-cock, so as to produce a light equal to that of a wax candle burning with full brilliancy; the relative intensity of the light of these flames was ascertained by a comparison of shadows. Under these circumstances, the consumption of gas was found 640 cubical inches per hour, or 0.37 cubical feet. When the same burner was used with oil-gas, it consumed 800 cubical inches per hour, or = 0.47 cubical feet.

I now employed an Argand burner, with a cylindrical glass, constructed in the usual way, with 12 holes, each of the same dimensions as that of the single jet, and forming a circle 0.7 inch diameter. The pressure being 0.5 inch, the flame was so regulated as to burn with its full intensity without producing smoke, and its light being measured by a comparison of shadows, it was found equal to 10 wax candles. The consumption of gas amounted to 2600 cubical inches, or about a cubical foot and a half per hour.

The apertures of burners for coal gas require to be considerably larger than those for olefiant or oil gas. In the burner employed in the following experiments, each hole was

inch diameter, and the circle upon the circumference of which they were placed, was 0.9 inch diameter. The light of the flame was found equal to five wax candles only, and the consumption of gas per hour amounted to 6560 cubical inches.

With a mixture of six parts by measure of hydrogen with five of olefiant gas, the light of the flame was somewhat more intense; and the quantity of gas consumed by the same burner, so adjusted as not to smoke, was 6000 cubical inches.

It appears from the above data, that to produce the light of 10 wax candles for one hour, there will be required, ·

and that the quantity of oxygen consumed

by the olefiant gas will be = 7800 cubic inches:

by the oil gas

by the coal gas

To ascertain the relative heating powers of the flames of olefiant, oil, and coal gases, I employed the 12-hole Argand burners mentioned above, and placed over each, as near to the lamp glass as was consistent with a clear flame, a clean copper boiler, 2.5 inches deep and five inches in diameter, slightly concave at bottom, capable of holding rather more than a quart of water, with an immersed thermometer, and a small vent for steam. It contained two pounds of distilled water, which was raised to the boiling point in similar times, namely, 20′ by each of the flames; so that it would appear, that to raise a quart of water from 50° to 212°, at 30 inches barometrical pressure, requires

870 cubical inches of olefiant gas.

1300
2190

oil gas. coal gas.

From this experiment it may be inferred, that the air of a room equally lighted by oil and coal gas, will be much less heated by the former than the latter; but that the actual heating power of the flames is in the direct ratio of the quantity of olefiant gas.

Experiments on the Condensation of several Gases into Liquids. By Mr. FARADAY.-[1822.]

MR. FARADAY'S experiments were made on sulphurous acid, sulphuretted hydrogen, carbonic acid, euchlorine, nitrous oxide, cyanogen, ammonia, muriatic acid, and chlorine, Sulphurous Acid. Mercury and concentrated sulphuric acid were sealed up in a bent tube, and, being brought to one end, heat was carefully applied, whilst the other end was preserved cool by wet bibulous paper. Sulphurous acid gas was produced where the heat acted, and was condensed by the sulphuric acid above; but when the latter had become saturated, the sulphurous acid passed to the cold end of the tube, and was condensed into a liquid. When the whole tube was cold, if the sulphurous acid was returned on to the mixture