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puré plumbago, and different kinds of charcoal, were successively exposed to the action of the lens, and from the results the following conclusions were deduced : viz. that the diamond affords no other substance by its combustion than pure carbonic acid gas; that, in the combustion of the different kinds of charcoal, water is produced, and from the diminution of the volume of the gas, there is every reason to believe, that the water is formed by the combustion of hydrogen existing in the charcoal.' He farther observes ;
· The general tenor of the results of these experiments is opposed to the opinion, that common carbonaceous substances differ from the diamond by containing oxygene ; for in this case they ought to increase and not diminish the volume of oxygene : nor, on the other hand, is it favourable to the supposition that the diamond contains oxygene, for the difference in the quantity of carbonic acid produced in the different experiments, is no more than may be reasonably ascribed to the generation of water, in the combustion of the common carbonaceous substances.
• That charcoal is more inflammable than the diamond may be explained from the looseness of its texture, and from the hydrogene it contains ; but the diamond appears to burn in oxygene with as much facility as plumbago, so that at least one distinction supposed to exist between the diamond and common carbonaceous substances is done away by these researches.'
. The only chemical difference perceptible between diamond and the purest charcoal, is that the last contains a minute portion of hydrogene ; but can a quantity of an element, less in some cases than goooo part of the weight of the substance, occasion so great a difference in physical and chemical characters? This is possible, yet it is contrary to analogy, and I am more inclined to adopt the opinion of Mr. Tennant, that the difference depends upon crystallization. Transparent solid bodies are in general non-conductors of electricity, and it is probable that the same corpuscular arrangements, which give to matter the power of transmitting and polarizing light, are likewise connected with its relations to electricity; and water, the hydrates of the alkalies, and a number of other bodies which are conductors of electricity when fluid, become non-conductors in their crystallized form.
Some Account of the fossil Remains of an Animal more nearly allied to Fishes than any of the other Classes of Animals. By Sir Ev. Home, Bart. - It is here observed that the study of comparative anatomy is not confined merely to the animals which at present inhabit the earth, but to such as may have formerly existed, although now extinet; and that, while it is the province of the geologist to explain the changes which have taken place in the globe, the anatomist must examine the fossil remains, and determine to what class of animal they belonged. The specimen of which this paper gives an account was found
between Lyme and Charmouth in Dorsetshire, and was brought to light by the breaking down of a part of the cliff that forms the shore. The cliff is composed of that species of argillaceous lime-stone which is called blue lias. We have next a minute description of the bones, accompanied by plates. Some parts of the skeleton induced the author to imagine that it belonged to an animal of the crocodile species : but other circumstances seemed to prove that it was a fish, although of a very uncommon kind. The general conclusion is that, like some of the animals found in New South Wales, this skeleton presents many deviations from ordinary structure, as if • for the purpose of making intermediate connecting links, to unite in the closest manner the classes of which the great chain of animated beings is composed.'
On an easier Mode of procuring Potassium than that which is now adopted. By Smithson Tennant, Esq. F.R.S. - This is an improvement and simplification of the process of MM. GayLussac and Thenard, who formed potassium by bringing into contact iron and potash both intensely heated : but, as Mr. Tennant remarks, it requires a furnace of a particular construction,- the two gun-barrels which are employed must be ground together, so as to be air-tight, - and, after all, the process is not constantly successful. It is not very easy to describe the most simple apparatus without plates: but we may remark that the improved method consists essentially in a barrel, inserted into the furnace in which the potash and iron are placed together; and a narrower piece of barrel is inserted in the upper part of the large one, into which the potassium rises by distillation, and is obtained in a state of purity. Mr. Tennant mentions, with his usual correctness, all the precautions which are necessary in the performance of the experiment.
On the Influence of the Nerves upon the Action of the Arteries. By Sir Ev. Home, Bart. It is the object of this paper to shew that the nerves which accompany the arteries regulate their actions, and that it is through their agency that the blood is transmitted in various proportions to the different parts of the body. The ingenious author supports this opinion by observations on the effect of injuries of the extremities, and by direct experiments. The following appears to be the most decisive:
• The carotid artery of a dog was laid bare, the intercostal nerve and par vagum, which form one bundle, were separated from it by a flattened probe for one-tenth of an inch in length, the head and neck were then placed in an easy position, and the pulsations attended to by all present, for two minutes, that the eye might be accustomed to them in their natural state : the nerve passing over the probe was then slightly touched with the kali purum. In a minute and a half the pulsations of the exposed artery became more distinct ; in two minutes the beats were stronger, and in three more violent ; in four minutes the violence was lessened, and in five minutes the action was restored to its natural state.'
Some experiments were then performed, by which it appeared that the topical application of cold had a direct effect on the action of the arteries, which was presumed to operate through the medium of the nerves.
On the Means of producing a double Distillation by the same Heat. By Smithson Tennant, Esq.— The heat, which is given out from condensed steam, has been employed in various ways for heating other bodies, and by these means water may be raised to the boiling point; but it cannot be converted into vapor, so as to pass over by distillation, because, as soon as the steam has imparted to water its own temperature, no farther transfer of heat takes place, and the steam passes through the water uncondensed. It is known that all fluids. may be converted into vapor at a lower than an ordinary temperature, by taking off the pressure of the atmosphere ; and on this principle Mr. Tennant has contrived a simple apparatus, in which the steam first formed passes through water contained in a vessel made air-tight, connected with a receiver, from the surface of which the weight of the air is removed. By, this apparatus, the product of distillation is nearly doubled, with the same quantity of fuel, and without any expensive or complicated machinery.
An Account of some Experiments on Animal Heat. By J. Davy, M.D. — The author of this paper observes that three circumstances, connected with this subject, particularly deserve attention ; viz. the relative capacities of venous and arterial blood for heat, their comparative temperatures, and the temperature of different parts of the animal body. In the experiments for ascertaining the relative capacities for heat of arterial and venous blood, he first remarked the time which each took in cooling, compared with water; and afterward the temperature which was produced by mixing given quantities of the two kinds of blood with water. The blood was examined both with and without the fibrine. A considerable number of experiments was afterward performed, on the comparative temperature of venous and arterial blood :
In each instance, a long incision was made through the integu. ments ; the jugular vein was laid bare, and the exact seat of the carotid artery found. The vein was then opened, and a small delicate thermometer introduced, and thrust about an inch up
the vessel beyond the wounded part; and as the bulb of the instrument
was small, the flow of blood was not stopped. When the mercury was stationary, its height was marked. The carotid artery next was divided, and the thermometer was immersed in the current of blood, and left there till it ceased to rise.'
The next set of experiments related to the comparative temperature of the blood in the two sides of the heart'; and afterward to the heat of different parts of the body. We shall transcribe some of the author's remarks and conclusions, which are not the less interesting as being at variance with many prevailing opinions.
. That there is no material difference between venous and arterial blood in respect to specific caloric, excepting what arises from difference of specific gravity ; that the temperature of arterial blood is higher than that of venous; and the temperature of the left side of the heart, than that of the right; and lastly, that the temperature of parts diminishes as the distance of the parts from the heart increases are the general results of the preceding experiments.
• Admitting the accuracy of these experiments, and I think that they will be found correct when repeated, what are their consequences in a theoretical point of view ?
• They are evidently in direct opposition to Dr. Crawfurd's hypothesis ; the essence of which is, that the capacity of arterial blood for heat is greater than that of venous, that there is no difference of temperature between the two ventricles of the heart, and in fact that the heat of all parts is nearly the same.
• They are more agreeable to, and indeed they even support the hypothesis of Dr. Black, that animal heat is produced in the lungs, and distributed over the whole system by means of the arterial blood.
• Neither are they inconsistent with that hypothesis which considers the production of animal heat as dependent on the energy of the nervous system, and arising from all the vital actions constantly occurring.'
• To conclude, as in each hypothesis examined, difficulties are found to exist from facts or the results of experiments of an unbend. ing nature, we must at present either suspend theory altogether and search for experimenta crucis, or adopt that hypothesis which is conformable to the greater number of facts. The first measure is certainly most philosophical ; but to the latter we are naturally most inclined, and if I were questioned which view is preferable, I should make no hesitation in selecting Dr. Black's, which to me appears both most simple and most satisfactory.'
This inference seems to be a fair deduction from the facts, and that in which we are disposed provisionally to coincide.
[To be concluded in our next Number.]
Ant. VII. History of the University and Colleges of Cambridge ;
including Notices relating to the Founders and Eminent Men.
will, we think, dispose most readers to regard with an evil eye the outworks which intercept their approach ; and to behold with displeasure the colossal figures with which, in the shape of Preface and Introduction, the artist obscures its front. Mr. Dyer complains of the narrow limits within which he is obliged to confine his undertaking; and yet we have to toil through seventy pages of prefatory matter, in which he is himself the leading topic, before we come to the first line of the work. Respectable and interesting as is the subject, we' have no doubt that most persons will be of opinion that it is unseasonably introduced, and too largely dilated. To a few preliminary pages, for the purpose of disclosing the sources whence the matter of these volumes has been derived, although the practice cannot boast the sanction of the first models, we give our unqualified approbation. Had Herodotus and Livy stated to us the foundations on which their immortal narratives rest, how gratifying would the examination of them have been at this day, and what light would have been reflected on antiquity? We should have felt a satisfaction in dwelling on their exquisite pages, for which the charms of composition but poorly compensate. --Although the present historian is not easily to be deceived as to the matters of which he treats, and is the last man who would wilfully impose on others, still are we glad to have the grounds submitted to us on which his superstructure is built; and, sharing as we do in the eagerness to peruse the work itself which we ascribe to other readers, we are far from complaining of these communications as improper : but, if the account which Mr. D. gives of his authorities is clear and satisfactory, we wish we could add that it is equally neat and concise. He divides them into two classes, namely, such as are in MS., and such as are in print:
- The first and most authentic documents respecting Cambridge lie in the archives of their respective colleges, and consist of charters of foundation, licences of mortmain, and bulls of popes ;
papers relating to livings, estates, and benefactors; to the customs and jurisdiction of the University, and fragments of college history, Many papers relating to different colleges are in the libraries so rich in MSS., Archbishop Parker's in Bene't's College, and Gonville's and Caius's. In the University there are but two or three, with the exception of Mr. Baker's.