whatever be the nature of this change induced on fibrin by the alkalies, the former is by no means converted, as M. Fourcroy has alleged, into a fatty substance with which the alkali produces a saponaceous compound, nor has it even the least analogy to any species of soap. As far as I can perceive, this effect of alkalies is confined to the epidermoid textures, and parts which by long and continued boiling are converted into a similar sub stance. Of the Colouring Matter and its Chemical Froperties. In order to separate, as much as possible, the colouring matter from the albumen and the salts of serum, I cut the crassamentum into very thin slices, which I placed upon blotting paper, till it had taken up all that it could absorb: after which they were dried. A portion of the crassamentum treated in that manner, was, triturated with water as long as it appeared capable of acting as a solvent. This water acquired from the matter it had dissolved a brown colour of so deep a shade that it did not exhibit the least transparency when contained in a glass tube of a quarter of an inch in diameter. The fluid had a faint odour of blood, and a mawkish, saline, and highly nauseous taste. I coagulated the solution by means of heat in a pneumatic apparatus. The mass frothed considerably, but no elastic fluid was disengaged. While yet hot, it was placed on a filter: the liquor had a red colour which it lost by cooling, and at the same time deposited a small quantity of the colouring matter. I shall revert to this liquor in the sequel. The dark brown coagulated matter, after being carefully washed, and subjected to a powerful press, was dried at a temperature of 70° (158° Fahrenheit). It was but little contracted by the exsiccation, but had become black, hard, difficultly pulverisable, and shewed a vitreous fracture. Before the desiccation is complete, it is of a dark brown colour, has little cohesion, and forms a granulated mass: circumstances by which it may be distinguished from both fibrin and albumen. 1. The colouring matter is acted upon by boiling water in nearly the same way as fibrin, becoming somewhat contracted by coction; and the solution contains soda, and an animal matter perfectly analogous to that which is obtained from fibrin, but rather less in quantity: for it would appear that a portion of this substance begins to be formed from the commencement of the process of coagulation. It retains its black colour, but loses the property of softening, and dissolving in acetic acid. 2. Alcohol and ether convert the colouring matter in part, into a fatty adipocirous mass, having a very disagreeable odour. 3. In acetic acid, the colouring matter immediately becomes soft, forming a black and tremulous jelly, which dissolves in tepid water with the disengagement of a small quantity of azotic gas. The solution is reddish brown, and only semi-transparent. A small part of the colouring matter remains undissolved, and forms with the acid a compound of very sparing solubility. A solution of the colouring matter mixed with acetic acid does not coagulate; but when made to boil turns black and deposits a very small quantity of its insoluble compound, without however coagulating. The solution of the colouring matter in acetic acid is precipitated both by alkalies and by alkaline prussiates. Ammonia produces a dark brown precipitate, which, when well washed and weighed, is found to be the colouring matter unaltered, and again soluble in acetic acid. The solution after precipitation by ammonia is yellow, and deposits by evaporation a quantity of white matter, which is readily distinguished to be albumen, of which it is impossible entirely to deprive the crassamentum. Prussiate of ammonia precipitates from the acetic solution a mass of a blackish brown colour, resembling the precipitate by pure ammonia. Both these precipitates, employed as pigments, give the same shade of a dirty brown. The prussic acid, therefore, appears to exert no action on the colouring matter of the blood; which should take place if the latter owed its colour to a ferruginous salt. The solution of colouring matter in acetic acid is precipitated by the mineral acids, and the precipitates have precisely the same characters, excepting the colour, which is brown, as those procured by the same methods from fibrin. 4. Concentrated muriatic acid does not dissolve the colouring matter, even when aided by digestion: a small quantity of azotic gas is disengaged, and the acid assumes a yellow tint alkalies, however, produce in it hardly any precipitate. The undissolved portion is a compound with excess of acid, which becomes soluble in proportion as the superabundant acid is carried off. The neutral solution of colouring matter is brown, and has the same properties as that formed by acetic acid. The colouring matter boiled for a long time with muriatic acid, suffers a commencement of decomposition: some iron is taken up by the acid, and the undissolved portion is no longer soluble even by repeated washing, although in this state it retains a portion of acid, of which the water cannot deprive it. 5. The nitric acid produces the same effects in the colouring matter as on fibrin; the only distinction being in the colour, which in the former is invariably black. 6. Caustic ammonia dissolves, the colouring matter assuming a very deep brown colour. A precipitate is thrown down by acids, but not by the alkaline prussiates. The precipitate formed by acetic acid is again soluble, but only by an excess of acid. 7. In solution of caustic fixed alkali the colouring matter is softened, forming a brownish jelly, which is dissolved by a sufficient quantity of water. During the evaporation it coagulates in proportion as the alkali absorbs carbonic acid. The alkaline solution is precipitated by alcohol, which, however, acquires a red tinge by dissolving a small quantity of the compound formed of the colouring matter with the excess of alkali. The alkaline solution of colouring matter seen by day-light has a green colour, but appears red by candle-light. It was upon this appearance of green that Foureroy conceived the idea that bile might be formed by boiling blood with a small quantity of water; but this green fluid, as we shall afterwards see, agrees with bile in no property excepting colour. 8. If a solution of the colouring matter in water be exposed to a heat of 50° (122° Fahrenheit) in a saucer, it blackens and dries completely without coagulating. In this state it is again entirely soluble in cold water. These experiments prove that the colouring matter has the same chemical properties, and consequently the same chemical composition as fibrin, but that these two bodies are distinguishable from one another principally by a difference in colour; by the fibrin coagulating spontaneously in all temperatures, while the colouring matter may be dried, without losing its solubility in water, and becomes insoluble only at a certain temperature: and lastly by the peculiar character of the latter when coagulated, such as its not being diminished in volume during the exsiccation, as happens with fibrin. (To be continued.) ARTICLE VII. On the Heat evolved during Inflammation of the Human Body. By Thomas Thomson, M.D. F.R.S. THAT the heat evolved by the human body is very considerable, and that in cases of inflammation this heat is very much increased, are facts with which every body is acquainted; but I am ignorant of any attempt hitherto made to estimate the increase of heat that is given off in cases of inflammation. On that account I think it worth while to record an observation which I had an opportunity of making upon myself, during the course of last winter. It is far from determining the whole heat given off during the inflammation; but as it is at least an approach towards accuracy, and as I was at as much pains as possible, considering the situation in which I was at the time, I conceive the statement will add another and a curious fact to animal physiology. During the month of January last, in consequence of walking about in rainy weather in thin shoes for a considerable part of the day, and afterwards sitting for several hours with wet feet, I caught a violent cold, which was attended with fever, and among other inflammatory symptoms a throbbing pain took place in the right groin, accompanied with swelling of the inguinal glands. To prevent this pain from proceeding to suppuration, I applied, for four days successively, and 36 times each day, two cotton cloths successively wrung out of cold water to the swelled part. The average temperature of the cold water employed was 40°. The cloths were removed when they felt hot; and from several trials this appeared to indicate a temperature of about 90°; so that each cloth, and the water which it contained, was heated at an average 50°. The first cloth dry weighed.... 530 grains The first when wet weighed 1459 or 929 water + 530 cloth The second... 1434 or 976 + 458 I made several experiments to determine the specific heat of cotton, but found it attended with unexpected difficulty. When cotton wool is employed it is so elastic and bulky that you are obliged to use a much smaller weight of it than of the hot water with which you mix it. This occasions great inaccuracy. When cotton cloth is employed, a considerable time elapses before you can mix it properly with the water, and this occasions uncertainty. I state, therefore, the results which I obtained with considerable hesitation. The specific heat of cotton, by my trials, is 0.53, that of water being 1. I shall therefore consider it as half as great as that of water. We may, therefore, substitute for the two cotton cloths a quantity of water equal to half the weight of each, We may say, therefore, that 2399 grains of water were heated 50 degrees 18 times a day for four days together, making a total of 30 pounds troy heated 50° in the course of four days by the inflamed part. This is nearly the same quantity of heat that would have been requisite to heat 8 lbs. of water from the temperature of 40° to that of 212°. This amounts nearly to seven wine pints. So that in the course of four days this small inflamed spot gave out a quantity of heat sufficient to have heated seven wine pints of water from 40° to 212°; yet the temperature was not sensibly less than that of the rest of the body at the end of the experiment. The inflammation, however, was gone, and did not again return. Nor was this quantity of heat, considerable as it was, the whole that was evolved. Some was lost by the evaporation of the moisture from the wet cloth, which must have taken place to a certain extent, and some must have made its escape during the night, when the wet clothes were applied very irregularly, and at long intervals. ARTICLE VIII. Mineralogical Observations made in the Highlands of Scotland. By James Grierson, M.D. On the 14th of August, 1812, Mr. Jardine, civil engineer, and myself, left Edinburgh on a round by Loch Catherine and Loch Tay, principally with the view of observing the geognostic appearances of the country. On reaching the bridge of Doune, eight miles from Stirling, we found the old red sandstone, forming nearly horizontal strata in the bottom of the river. Soon after this we observed on the road from Doune to Callander many rolled pieces of very distinct grey wacke, which led me to suspect the approach of a grey wacke country. From Callander we set out to visit the famed and interesting scenery of the pass of Leney, by which the traveller on this route enters the Grampian range. About two miles beyond Callander we found the rock through which the road is cut to be very distinct grey wacke, and traced it till we found it about half a mile farther on towards the north-west, very near the mica slate; but could not see the junction of these two rocks, or whether the clay slate intervened betwixt them. On this road, about a mile and a half from Callander (to the N. W. of it), we observed a greenstone vein, 12 or 15 feet broad, intersecting the conglomerate in a direction nearly N. E, and S. W. it crosses the high road. A little below this, towards Callander, transition slate appears in pretty highly inclined strata, and the conglomerate resting upon it, and, we thought, alternately with it. Neither of us could observe any instance of the conglomerate coming in contact with the clay slate; and we were both perfectly satisfied that in this district the transition rocks, grey wacke, and grey wacke slate, come in between the floetz and the primitive country. It was my intention to have examined particularly the species of minerals constituting the nodules of the conglomerate about |