ATDINI'S IMPROVEMENTS IN GALVANISM. small piece of wire to the dens sapientiæ, drawing it gradually over its surface; he then applies it to the next tooth, repeating the operation, and proceeds in like manner with the rest till he comes to the diseased tooth, which discovers itself by a violent pain, producing an involuntary commotion in the body. It is always remarked, that when this tooth is extracted, it exhibits a carious part not before visible. This method, therefore, is of great importance, as it frequently happens in such cases that the dentist, not being able to distinguish the diseased tooth from the rest, is obliged to draw some that are sound before he can discover it." Several experiments on the action of the galvanic pile on the blood, bile, urine, and other animal secretions follow. They deserve to be recorded, but nothing conclusive can be deduced from them, nor is it at all certain whether the change is any more than purely chemical. Two interesting dissertations follow, which were read by the author of the Institute of Bologna in the years 1793 and 1794. They are partly historical of the discoveries relating to galvanism, partly experimental, and partly controversial. The latter chiefly turns upon the opposite systems adopted by Galvani and Volta, the former supposing the galvanic action to originate in the living animal as a consequence of its organization, the latter ascribing the contractions only to external electricity, proceeding from the armatures, and not to any electric virtue in the animal. Three other appendixes are added to this volume. The first contains a summary of the experiments performed on the body of a malefactor hanged at Newgate, whilst Professor Aldini was in London. They have already been published separately, but they well deserve a place in this collection. The second appendix contains a report of similar experiments made by Vassali, Cardi, Giulio, and Rossi, on three criminals decapitated at Turin. The only circumstance enlarged on, is the much-questioned sensibility of the involuntary organs to galvanic action in warm-blooded animals. This sensibility is denied by Volta, and, as we have before mentioned, could not be detected by Aldini in the heart; however, the above experimenters fully ascertained it. They observe, "We tried the influence of galvanism on the heart in three different ways. "Ist, In arming the spinal marrow by means of a cylinder of lead introduced into the canal of the cervical vertebræ, and thus conveying The second experiment was by arming the par vagum and the great sympathe tic nerve. The third was by the pile itself, composed of fifty plates of silver and an hundred plates of zinc. Here, By making the negative extremity of the pile to communicate, by means of respective conductors, with the spinal marrow, or merely with the muscles of the back or breast, laid bare, and the positive extremity immediately with the heart, instantaneous and violent contractions were obtained; and the contractions were produced also when the heart was made to communicate with the negative extremity of the pile, and the spinal marrow with the positive extremity, the "We shall observe, in regard to contractions of the heart, that of all its parts apex is the most susceptible of motion, and the most sensible to the galvanic influence: we must observe also, that the contractions produced by communication with the pile were not only strong, but that they continued a long time even after the communication was destroyed." The last appendix relates an experi ment on the transmission of galvanism through a considerable extent of water in Calais harbour. The contents of this volume are somewhat desultory, but the experiments are so numerous, so wonderful, and so well contrived, and it contains so many curious conjectures and remarks on the theory of galvanism, that it must be considered as a most important acquisition to physiology. Perhaps it is the corner-stone of some noble monument of human wisdom, in as grand and useful a research as can employ the intellect, and exercise the ingenuity of man. We may add, that the plates are well executed, and the translator and editor has performed his office in a most respectable manner, that shews him to be acquainted with the subject as well as the language of the work which he here presents to the English reader. ART. III. History of the Progress and present State of Animal Chemistry. By W. JOHNSON, M.B. In three Volumes. THE utility of a work like the present cannot be better shewn than in the author's words. "Modern chemistry has already thrown great light on several parts of the animal system; it has, within these last few years, commenced an investigation of several of the functions of the body, and explained the manner in which they are carried on with some degree of success. The processes of respiration, of digestion, of animalization, and the action of oxygen upon vital organization, no longer remain in that state of total darkness in which they were so lately developed, whilst the proficiency already attained in this department of the science has established the animal analysis upon so firm and broad a basis as to promise in future the hap piest results. Other functions remain to be investigated, such as sanguification, ossification, nutrition, and the secretion of the different fluids; to which may be added the action of those powers that produce diseases, and that of medicines on the animal body; but it is by pursuing the same method of an analytical reasoning that their operations are to be explained, and their nature thoroughly understood. Every preparation is already made for this grand work, and there is reason to believe, that the route which has hitherto been explored will conduct the philosopher to a more precise and exact knowledge of the phenomena of the animal economy, and to the formation of a more perfect theory of the laws that govern the vital and mental world. "For such an undertaking a material advantage, however, seemed to be wanting: a compilation in which the enterprising experimentalist could be made acquainted with the facts and observations of those who had preceded him. It is true, several learned foreign chemists have attempted to supply this denciency, and Gren, Hildebrandt, Jacquin, and De la Grange, have published compilations on the subject; but their plans appear to have been too limited, and their descriptions too concise: many of the phenomena recorded in the analysis of animal substances have been excluded, some of the most interesting particulars have been forgotten. In the work now presented to the public a different plan has been pursued, a more enlarged For scale has been attempted, and an endeavour has been made to give the whole a more connected and systematic arrangement. these purposes, the author is principally indebted for his information to the Elementa Physiologia of Haller, the Encyclopédie Méthodique of Morveau and Fourcroy, and to Leonhardi's German Translation of Mac quer's Chemical Dictionary, with the excellent additions. At the same time, copious extracts have been occasionally selected from more recent publications, particularly those collections of different learned societies, to whose diligence and industry chemistry presents her choicest store. From the former, the early historical part has been chiefly taken; from the latter, the state of analysis of the present day. With such assistance, it is to be hoped, the deficiencies of former compilers may have been in some measure supplied, and the knowledge they have col lected increased, by having had access to a more extensive mass of materials, and to later discoveries." A compilation of this kind requires considerable talents. The author should be extensively read in physiology and in chemistry, and in some degree in natural history; he should have abundant patience and diligence in research, judgment in the arrangement, and impar tiality in selection. Amidst the immense profusion of chemical detail which lies scattered in books of various languages, it is the most valuable present that can be made to the young physiologist to perform for him that task of selection which is so irksome to original genius, and which is rewarded with no higher reputation than that of pains-taking industry. It is therefore with great satisfaction that we find this important office performed in these volumes, in a way highly creditable to the author, who has presented by far the completest view of animal chemistry that exists, and one which is calculated to be a standard book of reference for every medical and che mical library. The nature of the work renders any particular specimen unnecessary; we shall therefore only mention that the plan is very simple and unembarrassed. The two first volumes are occupied with the chemical analysis of all the solids and fluids of animal bodies, including a history of every important series of experiments that have been made in modern times, and are scattered through journals, elementary works, miscellanies, &c. in different languages. Of these, the German authorities have been examined with considerable minuteness, and indeed the general execution of the work some what reminds us of German industry and of German exhaustiveness in selection. The third volume examines the chemical changes that take place in the living body, of which the subjects of animal heat and respiration stand conspicuous, and are treated with peculiar care. As the author only aims at accuracy in compilation, and clearness in description, it would be unfair to expect a dif ferent excellence; his task is well performed, and we doubt not that public approbation will bear testimony to its utility. ART. IV. A System of Theoretical and Practical Chemistry. In Two Volumes, with Plates. By FREDERICK ACCUM, Teacher of Practical Chemistry, Pharmacy, and Mineralogy, and Chemical Operator in the Royal Institution of Great Britain. Svo, Pp. 800. CHEMISTRY is now become a subject of such vast extent, that a familiar acquaintance with every branch of this science is hardly to be expected from any individual, nor have we yet seen a single system which has any real claim to be considered as perfect. In some the pneumatic part is chiefly insisted on, in others the metallic substances are the favourite objects, others again are principally valuable for the chemistry of vegetable and animal bodies. The forte of some authors consists in a clear and perspicuous account of the prevailing theories and opinions, while others endeavour to render themselves useful to the operating chemist. The work before us is a very convenient manual for a lecturer, and will be found of equal use by the student who wishes to repeat in his own laboratory some of the most striking and beautiful experiments of modern chemistry. The first volume, which is principally occupied by caloric and the gasses, is the most useful, and contains a multitude of well selected experiments which are not generally known. The second volume, which comprehends the metals, earths, acids, alkalies, compound salts, vegetable and animal substances, &c. is much too crowded to be of any great value. The general plan which Mr. Accum has adopted, with regard to those substances that he treats of the most at length, is to appropriate a chapter to each, which he divides into two sections; in the first he enumerates the characters, and the several modes of obtaining the substance in a pure state, and the second is appropriated to experimental proofs of the va rious properties with the rationale of the more complicated processes. As a specimen of the work we shall select part of the second section concerning phosphorated hydrogen gas. "EXPERIMENT I. "Phosphorated hydrogen gas takes fire on coming into contact with atmospheric air. "This may be evinced by charging a small retort with potash, phosphorus and water, heat and dipping the mouth of the retort into in the manner mentioned before, applying a bason of water. The bubbles of the air, which come from the retort and pass through the water, will burst with a slight explosion, and produce flashes of fire in the circumambient air. A circular dense white smoke rises horizontally like a ring, enlarging itself continually, and forming a sort of corona extremely beautiful if the air be perfectly tranquil. flashes of gas succeed each other but slowly. "The finest effect is produced when the "Rationale. We have noticed before, that phosporated hydrogen gas is nothing but hydrogen gas holding phosphorus in solution. When this gaseous fluid is presented to the atmospheric air or oxygen gas, the minutely divided phosphorus rapidly attracts oxygen the hydrogen gas in contact with atmospheric and kindles, setting fire at the same time to air, and hence phosphoric acid and water are formed. The circular crown of white smoke which rises after the explosion of the gas, originates from the coat of water which enveloped the bubble of the gas; this water, together with what is formed during the explosion, is suddenly converted into vapour, and thus constitutes the circular crown of it unites to the phosphoric acid produced, smoke which rises in a ring. "If a wider-mouthed phial be filled with phosphorated hydrogen gas, and left in that situation over mercury, the gas will take fire when suffered to escape into the air by inclining the phial. "Remark. This last is a hazardous experiment, the phial is often burst to pieces; it is therefore necessary to surround it with a cloth in order to avoid dangerous events. An elastic gum-bottle may be used for this purpose with safety. "EXPERIMENT II. "Accension of phosphorated hydrogen gas by means of oxygen gas. "Fill a receiver with oxygen gas and convey into it a few bubbles of phosphorated At the instant of the union hydrogen gas. of the gases a brilliant flash of fire takes place, accompanied with a report. "The rationale of this experiment is analogous to the former. Remark. Great caution is necessary in performing this experiment. The dilatation of the gases, which takes place during the explosion is so great, that the vessel is apt to be blown to pieces. Not more than a single small bubble of the phosphorated hydrogen gas should be conveyed into the oxygen gas at once, except the receiver be made of very thick glass. Phosphorated hydrogen gas burns with e green light in nascent oxygenated muriatic acid gas, under the surface of water. Put into an ale-glass, or Florence Aask, one part of phosphoret of lime, broken iz: pieces of the size of a pea (not in small fragments or in powder) and add to it half a pat of oxygenated muriate of potash. Fill the vessel with water, and bring carefully into contact with the materials at the bottom of sulphuric acid. This may be most convers the fluid, three or four parts of concentrated ently done, by letting the acid fall through a long-necked funnel, reaching to the bottom "Accension of phosphorated hydrogen gas, the sides of it. As soon as the decomposi of the vessel, or by causing it to pass down by means of oxigenated muriatic acid gas. If fresh-prepared phosphorated hydrogen tion of the water and that of the oxygenated gas and oxygenated muriatic acid gas are min-muriate takes place, flashes of fire dart from gled together over mercury, a considerable detonation takes place, accompanied with a lambent green flame and dense white vapours. << EXPERIMENT III. the surface of the fluid, and the phosphoret illuminates the bottom of the vessel with a beautiful green light." ART. V. Lectures on the Elements of Chemistry; delivered in the University of Edin burgh, by the late JOSEPH BLACK, M. D. &c. Now published from his Manuscript, by John Robison, LL. D. Projessor of Natural Philosophy in the University of Ediaburgh. 4to. Two Vols. THE name of Dr. Black will proba bly be remembered as long as the science of chemistry exists: his two great discoveries of latent heat and of the cause of that difference observable between the properties of the mild alkalies and alkaline earths, and of these substances, when in a caustic state, must be acknowledged, by all philosophers, as having communicated the impulse, and pointed out the way to the splendid investigations of modern chemistry. These claims on the remembrance of posterity could never have been set aside, even if the present publication had not taken place. Still it is in a high degree satisfactory to possess a record of them in the words of their author, more especially as we by this means become ac quainted with the manner, and may form some faint idea of the effect produced by the lectures of this celebrated teacher. Professor Robison, the former pupil, and intimate friend of Dr. Black, was entrusted, by his executors, with the arduous and delicate office of revising the loose manuscript notes, from which Dr. Black delivered his lectures, and reducing them to a state proper for publication. The documents of Dr. Black's fame could not have been committed to abler hands: the volumes before us c1hibit a very accurate representation, not only of the opinions, but, we doubt not, of the very words of the author; while the notes, which the editor has supplied, from the stores of his own knowledge, confer an additional value on the work A very interesting life of Dr. Black, by the editor, is prefixed, in which the progress of his discoveries is minutely and satisfactorily detailed, and a very equitable estimate formed of his philosophical merit. It was not to be ex pected that the friendly partiality of his biographer should touch otherwise than very lightly upon the characteristic failing of Dr. Black's later years: it ought not, however, to have been either denied or justified: if a mean economy was allowed to interfere with his duty as a professor; if the laboratory establishment was scandalously deficient in apparatus of absolute necessity, what a strange proof of Dr. Black's "correctness and propriety of conduct" is it, to say, that his house was spacious, his table plentiful and elegant, rather above than below his condition." The concluding scene of Dr. Black's life was most singularly calm and happy. "His only apprehension,' observes Professor Robison, was that of a long-continued sick bed; and this, perhaps, less from any selfish feeling than from the humane consideration of the trouble and distress occasioned to attending friends; and never was this modest and generous wish more completely gratified. On the 26th Nov. 1799, and in the seventy-first year of his age he expired, with out any convulsion, shock, or stupor, to announce or retard the approach of death. Being at table with his usual fare, some bread, prunes, and a measured quantity of milk, diluted with water, and having the cup in his hand when the last stroke of his pulse was to be given, he set it down on his knees, which were joined together, and kept it steady with his hand, in the manner of a person perfectly at ease; and in this attitude expired, without spilling a drop, and without a writhe in his countenance; as if an experiment had been required to shew to his friends the facility with which he departed. His servant opened the door to tell him that some one had left his name, but getting no answer, stepped about half way towards him, and seeing him sitting in that easy posture, supporting his bason of milk with one hand, he thought that he had dropped asleep, which he had sometimes seen happen after meals. He went back and shut the door; but before he got down stairs some anxiety, which he could not account for, made him return and look again at his master. Even then he was not satisfied, after coming pretty near him, and turned to go away; but again returned, and coming quite close to him he found him without life. "So ended a life which had passed in the most correct application of reason and good sense to all the objects of pursuit which pro vidence had prescribed to his lot; with many topics of agreeable recollection, and few things to ruffle his thoughts. He had long enjoyed the tender and affectionate regard of parents whom he loved, honoured, and revered; with the delightful consciousness of being a dutiful son, and being cherished as such;-one of a family remarkable for sweetness of disposition and manners, he had lived with his brothers and sisters in terms of mutual love and attachment. He had never lost a friend but by the stroke of mortality, and he felt himself worthy of that constancy of regard. He had followed a profession altogether to his taste, and had followed it in a manner, and with a success which procure ed the esteem and respect of all competent judges, and set his name among the most eminent, and he was conscious that his reputation was not unmerited; and with a success, in respect of emolument which secured the respect, even of the ignorant; and gave the command of every rational gratification, and enabled him to add greatly to the comforts of the numerous descendents of his worthy parents,-heirs not only of their name but likewise of their unambitious moderation, and amiable simplicity of character." him The contents of these volumes have somewhat of an air of confusion, arising in some degree, perhaps, from the imperfect state in which Dr. Black's manuscripts were found at his death, but principally from the partial adoption of new nomenclature and late discoveries, These appear to have been inserted in his lectures at various times, as each approved itself to his judgment, while the natural feebleness of old age, added to an originally delicate constitution, disabled him from remodelling the whole into a harmonious system. A large, we will not say a disproportionate share of the work, is devoted to the illustration of the author's own immortal discoveries, which are related with great minuteness and in a most engaging manner; and it is particularly satisfactory to behold on all occasions a most happy exemption from jealousy of his fellowlabourers in the inexhaustible mine of experimental knowledge, and the most scrupulous equity in assigning the fame of great discoveries to the rightful claimants. |