mit of precision. But it is not the experiments on arterial blood, though these are the only ones alluded to by Mr. Brodie; it is the experiments on the specific heat of the aerial bodies connected with respiration that constitute by far the most difficult part of the investigation. If Dr. Crawford's statements respecting the specific heats of oxygen gas, atmospherical air, and carbonic acid gas, be admitted, we do not see how it is possible to reject the conclusions to which he has come. Let us take his statements for granted, and see what will follow. According to him the specific heats of these gases are as follows: Now let us take any one of Mr. Brodie's experiments, as, for example, the second. The rabbit converted th of the bulk of the air into carbonic acid gas; or, which is the same thing, th of the oxygen was changed into carbonic acid. Of course, its specific heat was sunk from 4.749 to 10454. To get a base of calculation, let us suppose the absolute quantity of heat in bodies at the temperature of 65° to be 1500 degrees. In that case, no less than 1170 degrees of heat will be disengaged merely by the change of the oxygen into carbonic acid gas. This quantity has to be divided over 18 parts of an air consisting of a mixture of 79 azotic gas 15.5 oxygen gas 100.0 Now the specific heat of this mixture will be obtained by multiplying these numbers respectively into the specific heat of each of these gases, adding the products together, and dividing the sum by 100. This operation gives us the specific heat of the residual mixture, after respiration, 1420. The 1170 degrees of heat divided into 18 parts gives 65 degrees for each part; but as the specific heat of the residual gas is 1·42, these 65 are only capable of producing an increase of temperature equivalent to 45 7 degrees. The air, when drawn in, was 65°; it ought, therefore, when thrown out, to be of the temperature of 110°-7; but as its temperature is only about 100°, there are 107 degrees of heat to be accounted for, and which can only be accounted for by supposing it to be absorbed by the body. If we were to suppose, with Mr. Dalton, that the absolute heat of bodies amounts to 6000 degrees, in that case no less than 4679 degrees would be disengaged from the oxygen by its change into carbonic acid. This ought to heat the residual air up to the temperature of 247.7 degrees; so that no less than 147.7 degrees must have entered the body. I do not, for my own part, lay any stress upon these estimates, because I consider the whole doctrine relative to the absolute heat of bodies as destitute of foundation, and because I conceive Dr. Crawford's experiments to determine the specific heat of the gases as too delicate to admit of precision. They are stated merely to show that Dr. Crawford's theory does not depend alone upon his estimate of the specific heat of arterial and venous blood. It is the result of a very numerous train of experiments, investigated with much labour and ingenuity, and all admirably coinciding in one point. The difference between the specific heat of arterial and venous blood, serves only to account for the circumstance that the temperature in the lungs is not higher than in other parts of the body, and to explain in what manner the heat absorbed in the lungs is gradually developed during the circulation. Independent of Dr. Crawford's experiments, there are other circumstances which throw considerable plausibility upon the opinion that heat is evolved by respiration. Every body knows that those animals that do not perspire are cold blooded, and that in ourselves the temperature increases when we respire more rapidly than usual, and likewise when the circulation becomes accelerated. The change of oxygen gas into carbonic acid gas is accompanied with an evolution of heat in all other cases with which we are acquainted. This holds in combustion in a remarkable degree. It holds no less remarkably during the fermentation of malt liquors. Why should it not hold equally in respiration? These circumstances are not sufficient to set aside Mr. Brodie's experiments, which seem to have been made with great care, and which are very satisfactory; but they ought to induce us to consider the subject on all sides before we embrace the conclusion to which these experiments seem to lead. Living bodies do not seem to be subject to the same laws as dead matter. Mr. Brodie has shown that animal heat depends upon the action of the brain. Dr. Currie, in a very interesting paper published in the Philosophical Transactions more than 20 years ago, but to which physiologists have hitherto paid no attention, has shown, by experiments little less conclusive than those of Mr. Brodie, that the evolution of heat is connected with the action of the stomach. I shall take the first opportunity that occurs to reprint Dr. Currie's paper in a future number of the Annals of Philosophy, in order to contribute as far as in my power to draw the attention of physiologists to a very curious subject still imperfectly understood. XXI. On the different Structures and Situations of the Solvent Glands in the Digestive Organs of Birds, according to the Nature of their Food, and particular Modes of Life. By Everard Home, Esq. F.R.S.] This is a very interesting paper, and throws considerable light upon a branch of comparative, anatomy not hitherto much attended to. Sir Everard Home divides the digestive organs of birds into four parts. The first is the dilatation of the oesophagus, which forms a reservoir for the food, and which is called the crop. The second is the part into which the ducts of the solvent glands open, and which he calls the cardial cavity. The third is the cavity embraced by the digastric muscle, or gizzard. The fourth is the space between the opening of the gizzard and beginning of the duodenum, which he calls the pyloric cavity; though in some instances, he says, it hardly deserves that name. He describes the structure of these organs in the golden eagle (falco chrysaetos), the sea eagle (falco ossefragus), the hawk (falco nisus), the soland goose (pelecanus bassanus), the heron (ardea cinerea), the cormorant (pelecanus carbo), the sea gull (larus canus), the woodpecker (picus minor), the little ant (alca alle), the pigeon (columba domestica), the swan (anas cygnus), the goose (anas anser), the common fowl (phasianus gallus), the turkey (meleagris gallipavo), the parrot (psittacus aestivus), the casowary (casuarius emeu), the American ostrich (rhea Americana), the African ostrich (struthio camelus). XXIÍ. On some Combinations of Phosphorus and Sulphur, and on some other Subjects of Chemical Inquiry. By Sir Humphrey Davy, Kt. LL. D. Sec. R. S.] This paper contains the following valuable additions to our knowledge of the combinations of phosphorus and sulphur. 1. Phosphorus combines with two proportions of chlorine. The first of these is a limpid liquid; the second a white sublimate. To the first of these Sir H. Davy has given the name of phosphorane. It may be formed by passing the vapour of phosphorus through corrosive sublimate. It is composed of 100 phosphorus united to 333 of chlorine. It dissolves phosphorus. The sublimate, called phosphorana, is composed of 100 phosphorus united to 333 × 2 of chlorine, or €66. When phosphorane is mixed with water, aud slowly evaporated, crystals in the form of four-sided prisms make their appearance. These consist of phosphorous acid combined with water. Phosphorana, treated with water in the same way, forms a thick viscid substance, which consists of phosphoric acid united with water. 2. When these crystals of hydrophosphorous acid, as Sir Humphrey Davy calls them, are heated, they are converted into phosphoric acid, and a peculiar gas escapes, to which he has given the name of hydrophosphoric gas. Hydrophosphoric gas is not spontaneously combustible; but it explodes when mixed with air, and heated to a temperature rather below 212°. Its specific gravity is 0.87, that of air being 1:00: 100 cubic inches of it, under the ordinary pressure and temperature, weigh 26.53 grains. Its smell is disagreeable; but not so much so as that of phosphureted hydrogen gas: three measures of it require rather more than five measures of oxygen gas for complete combustion. When potassium is heated in it, its bulk is doubled, phosphuret of potassium is formed, and the residual gas is hydrogen. When sulphur is heated in it, the bulk is also doubled, sulphureted hydrogen gas formed, and a compound of sulphur and phosphorus remains. Hence the gas is a compound of 4.5 hydrogen and 22:03 phosphorus, or of 100 hydrogen and 489-56 phosphorus. 3. When phosphorus is converted into phosphoric acid, by combustion in oxygen gas, every grain of phosphorus consumes 4 cubic inches of oxygen. Hence phosphoric acid is composed of 100 phosphorus united to 150-5 oxygen. Phosphorous acid contains just half the oxygen present in phosphoric acid, or it is a compound of 100 phosphorus and 75.25 oxygen. 4. When phosphorus is slowly burnt in the air, the liquid produced is a mixture of phosphoric and phosphorous acids. When phosphorus is burnt in rare air at a moderate heat the solid acid produces phosphorous acid. 5. The specific gravity of sulphurous acid gas is 2∙193, that of air being 1000, and 100 cubic inches of it under the usual temperature and pressure weigh 66-89 grains. It is composed of equal weights of oxygen and sulphur. When oxygen gas is converted into sulphurous acid gas the bulk is not altered. 6. The specific gravity of sulphureted hydrogen gas is 1.177, that of air being 1000: 100 cubic inches of it, under the common temperature and pressure, weigh 35.89 grains. It is composed of 100 parts, by weight, of hydrogen and 1509 of sulphur. 7. Sulphuric acid, free from water, does not appear possible to be formed. Dry sulphurous acid gas and nitrous acid gases have no action on each other. 8. The liquid compound of sulphur and chlorine, which I discovered about eight years ago, is composed of 30 sulphur and 67 chlorine. 9. Water has the property of combining in definite proportions with a great number of bodies, and it has a considerable effect on their properties. In this manner it combines with the earths, alkalies, and most of the metallic oxides, ARTICLE IX. SCIENTIFIC INTELLIGENCE; AND NOTICES OF SUBJECTS I. Vegetables found in some species of Minerals. Professor Blumenbach, of Gottingen, in a letter to Von Moll, says, that though he had hitherto disbelieved the occurrence of vegetable bodies in the dendritic variety of chalcedony named mocha stone, he must now admit that it does sometimes contain true vegetables, apparently of the nature of conferva. He observed these in specimens from Iceland and Catherinenburg. The same celebrated zoologist received from Dr. Lichtenstein, the traveller, a very remarkable agate, which was worn as a precious amulet by a Japanese prince. On examining it, he discovered in its interior the fructification of an unknown plant, somewhat resembling the sparganium erectum. II. Turquois. Dr. Langsdorf, who accompanied Captain Krusenstern in his voyage round the world, presented to Blumenbach an uncut turquois, from Nischabar, in Eastern Persia. From the specimen it appears certain that this substance is not a petrifaction, but a particular mineral species which occurs in nests in beds of clay. According to the analysis of Dr. John it appears to be nearly allied to mollite (siderite). III. Chromium in Chlorite. Mr. Bergweser Uttinger, of Sontkofen, has discovered from 1 to 1 per cent. of chromium in a green coloured mineral heretofore considered as chlorite, and which gives a green colour to some kinds of sandstone. This mineral occurs in masses, from the size of an inch to that of a pea, in grey shell limestone and grey sandy marl. It occurs also disseminated in compact and lenticular clay iron stone. It thus appears that chromium is far from being circumscribed in its distribution. IV. Italian Rocks. Mr. Giuseppe Gautieri, principal inspector of forests in the kingdom of Italy, has lately examined the interesting valleys of Fiemme, Fassa, and Livinalunga, and finds the rocks to belong to the floetz trap formation, and to resemble in every respect the trap hills near Verona, Vicenza, and Padua, which have been described by many mineralogists as volcanic. V. Gieseke, the mineral Dealer. This Gentleman was mentioned in a paper on Greenland |