gluten would not be separated; and the starch would neither be so white, nor crackle under the fingers, when bruised *. Perhaps the acid may be useful in manufactures or chemical processes; but on these points M. Vauquelin is unable to decide, as he is not acquainted with the comparative value of vinegar, or of the refuse of the starch employed in feeding hogs.-M. Deyeux, in a note subjoined, communicates the analyses of the same waters, by MM. Le Sage and Parmentier. These are not, however, so complete or satisfactory as the analyses of Vauquelin; but he adds, that, according to the grain or water employed, the acid fluid contains some additional ingredients.

Mr. Woodhouse has published some observations on the objections of Dr. Priestley to the Antiphlogistic System, in the Medical Repository, an American collection. These, and some remarks in a separate publication, are abridged in the present volume; and, on the whole, we perceive that this chemist, though in favour of the doctrine of Lavoisier, finds some of Dr. Priestley's objections correct. In these experiments, however,-viz. in that where zinc was reduced by carbone, a new gas was discovered, which burns, when lighted, in common air; detonates, though feebly, with oxygenous gas, and requires a large quantity of it. It is lighter than carbonic acid gas, and heavier than carbonated hydrogen-the weight being nearly that of atmospheric air. When inflamed over oil or mercury, it affords no water; and it then leaves carbonic acid air in perfect purity. The same gas is obtained by treating oxyd of zinc with plumbago, and exposing carbonate of barytes with pulverised charcoal to the fire. Charcoal, in a porcelain tube, heated red, will produce the same air, if carbonic acid gas be repeatedly passed through it. This is therefore an oxydated gas of carbone.

To prevent any interruption, we shall ject as treated in the thirty-ninth volume.

pursue the same sub

M. Guyton read to the National Institute a memoir on the Combustion of the Oxydated Gas of Carbone without Heat. He found that the carbone was in a very different state from that in which it forms the carbonic acid and hydrogenated carbonic gas; and is not in a condition to act on a solution of metals the most easily reducible. It may, he found, be in part burnt by the oxygen of the oxygenated muriatic acid, and then acquires all the properties of the carbonic acid; but this combustion operates only gradually, as if the affinity were chiefly determined by the mass of oxygen in action; and, in reality, it is only reduced to carbonic acid by operating repeatedly on the same gas. MM. Desormes and Clement have,

Might not an acetous acid be added?-Ray,

however, elucidated the subject more completely, in a memoir on the Reduction of the White Oxyd of Zinc by Charcoal, and on the Oxydated Gas of Carbone which results from it.' Their experiments are varied and minute; but we cannot follow them closely. They have clearly proved the existence of an aërial oxyd of carbone, whose proportions of carbone vary from 46 to 52 parts in 100, according to the quantity of charcoal employed, and the temperature at which the mixture is made. It is singular that this gas cannot be produced directly by uniting the given quantities of carbone and oxygen, and that it is only formed by adding carbone to carbonic acid. They in vain attempted to form it by suffering oxygen to pass slowly over red-hot charcoal: the result was only carbonic acid, unless it remained long in contact with the carbone. A striking experiment was that in which the hydrogen decomposes the carbonated gas by taking away its oxygen. The abundance of the former principle is perhaps necessary to the decomposition, and is analogous to that of the carbonic acid with phosphorus, where the greatest affinity is determined by the largest mass. Its action on vegetable and animal substances they determine to examine at some length. This part of their labours is not, however, yet published. To return to the thirty-eighth

volume

M. Thenard's process for purifying the Oil of Colsa will not admit of abridgement.

M. Lunel's memoir on the Distilled Waters of some Plants, called Inodorous,' merits particular attention, in a pharmaceutical, rather than a medical, view. He contends that the distilled water of plants, without smell, is by no means on a footing with simple water in its purest state; and thinks that, as in mineral waters, the minute division of the impregnation may add to its medicinal powers. These are to be obtained by adapting the degree of heat, and the quantity of water, to the different plants, according to their nature; but he gives no directions for this purpose, according to the different qualities of plants.

M. O. Reineche's Observations on the Means of discovering the Presence of Lead in Wine' afford an useful example of this kind of analysis. The wine in question did not contain an atom of the metal.

M. Crell's miscellaneous Letter affords nothing very interesting, except an account of a mineral found in Cornwallcalled, by a ludicrous mistake, Cornwallis. It occurred in steatite, and was in powder or in irregular masses; of a yellow colour externally, internally of a shining white; thin and brittle be. tween the fingers. It is a mixture of several metals; but zinc is in the largest proportion. It contains also a large proportion of sulphuric acid, as well as of water of crystallisation.

The Memoir on the Culture of the Sweet Beet in France' offers nothing very interesting. We find that M. Adam of Rouen has made a considerable improvement in the process of distillation. He draws at once the most rectified spirit, at five sixths of the expense, without its having any bad taste or smell, though extracted immediately from the lees.

The first article in the thirty-ninth volume is entitled Observations on the Action of Sulphat of Iron on Nitrous Gas.' This refers to a former memoir in the Egyptian Transactions, noticed in this journal-the conclusions of which were disputed by M. Humboldt, assisted by M. Vauquelin. Berthollet is willing to appeal to the latter, as his judge. We cannot engage in this controversy, which hinges on the point, Whether the azote that remains after the absorption of nitrous gas, be a part of that gas, or the effect of the action of the sulphat of iron ? We must add, however, that the traces of the muriatic acid discovered by this author, and mentioned in the same memoir, proceeded from the filings of steel employed, and were owing to an accidental impregnation.

A Memoir on the Magnesian Earth, known by the Name of Earth of Salinelle, or Sommières.' The author's profession is the manufacture of alum; and his object is of course to discover clays peculiarly rich in alumine, and nearest to his manufactory. The earth in question is magnesian, and has the same relation to magnesia which clays have to alumine. It may be styled a true magnesian earth, though, as in clays, the flint is the predominating ingredient. The proportion of magnesia is 0.22; and the earth is employed by our author in making the sulphat of magnesia (Epsom salt).

An abstract of M. Guyton's Treatise on the Means of purifying Air, preventing Contagions, and checking their Progress,' by M. Deyeux, follows. The author used the fumes of muriatic acid; but he gives also an account of the employment of the other mineral acids. He then examines the subject chemically, and takes, as his example, the air from putrefied beef. We may observe, however, that this is by no means a fair example; as putrefying vegetables and a marshy soil are the more common causes of putrid diseases; and, where they arise from the animal kingdom, it is from the confined effluvia of a human body, not in itself putrid. M. Guyton found, in the putrid effluvia just mentioned, that carbonic acid gas was in a larger proportion than atmospheric air; but the effects were not owing to this gas, as, after its separation, there was a simi lar odor. No separate ammonia was discoverable. In the eudiometer, this putrid air was not found to contain less oxygen than common air. With respect, however, to the nature of these emanations, even his chemical knowledge could obtain no satisfactory information; and his attention was next directed to the

means of separating or decomposing them. Cold water, lime, resinous and aromatic bodies, fires, the explosion of gunpowder, and the vinegar of the four thieves,' had no effect in destroying the fœtor of these effluvia. Vinegar was successful, but only after copiously and repeatedly washing them with it. The acetic acid had a very rapid and powerful effect; but the expense prevents its general use. The sulphuric acid is not sufficiently volatile; and the nitrous acid, though powerful in correcting the fœtor, is inconvenient, as, when raised in vapour, it always contains nitrous gas, which is injurious to the health of those who breathe it. The muriatic acid, particularly the oxygenated muriatic acid, was equally convenient and powerful, and, in our author's opinion, merits the preference. This leads our author to speak of oxygenated remedies, as preventives or cures of infection. He would extend them to hydrophobia, itch, and the plague; as he thinks they have already been shown by Mr. Cruickshank to destroy the infection of the small-pox, and the syphilitic poison by others. M. Guyton, however, is no physician.

MM. Fourcroy, Vauquelin, and Thenard, have been employed in Galvanic experiments. By augmenting the diameters of the discs, they found the commotions and the decomposition of water not augmented or accelerated; but the combustion of metallic wires was immediately affected, and in oxygen gas the combustion was rapid with a brilliant light. Combustion is therefore in the ratio of the diameter of the plates; the other phænomena, in that of their number,

A Gummy Substance has been discovered in the Root of the Hyacinthus non scriptus. It appears to be a pure gum, and may be extracted, in M, Leroux's opinion, with advantage. Since that time the author has converted it, we find, into an amylaceous matter, and in the fortieth volume gives a fuller account of this substance. The root is richest at the period previous to its caulescence; and the author explains at length the manner of collecting the fluid gum. He found the substance soluble in double its weight of cold water; but in a smaller quantity of warm water, to which it gives a lentor like gum, It is not easily powdered, and on burning coals exhales the odor of syrup. The coal is light, and the ashes contains a small proportion of lime. When distilled, it affords the pyromucic acid in large quantities. It is not dissolved by alcohol, is blackened by sulphuric acid, with the mixture which exhales a sensible odor of acetous acid. The nitrous acid converts it into oxalic; the muriatic and acetous acids scarcely change it.

It is singular that, in coagulating, it becomes white, and assumes an amylaceous nature; in general, indeed, a mucilaginous state precedes the amylaceous. The author found this gum, when the amylaceous change was less conspicuous,

useful in a variety of manufactures, particularly in calico-printing, hat-making, ink-making, &c.

As our article has extended beyond our expectations, we must defer the remainder of the volume to another opportunity.

ART. X.- Médecine Légale et Police Médicale de P. A. O. Mahon, Professeur de Médecine Légale, &c. Avec des Notes du C. Fautrel, ancien Officier de Santé des Armées. Paris. Forensic Medicine and Medical Jurisprudence. By P. A. O. Mahon, Professor of Forensic Medicine. With Notes by C. Fautrel, a Senior Officer of Health to the Armies. 3 Vols. 8vo. Imported by De Boffe.

THE different constitution of the criminal tribunals of England and the nations on the continent have made forensic medicine (médecine légale) a subject of much greater importance in other countries than our own. In England, the questions submitted to the medical men are few and general: unfortunately, their evidence has been proportionally inconsiderate and unsatisfactory; nor have many important points been submitted to their decision, where we can compliment them for their judgement or their discrimination. This branch of medical education has indeed been much neglected-though we apprehend it has lately made a part of Duncan's course; and the publications on this subject have been very few and unsatisfactory, including only, in general terms, the signs of pregnancy, effects of poisons, and the doubtful marks of a child having breathed from an examination of the lungs. If with these trifling works (trifling in every sense of the word) we compare the publications on the continent, the contrast will be considerable; though, as we have already remarked, the practice of the criminal courts greatly varies, and may occasion the difference. A few only of the more important publications, as they occur to us, we will mention; viz. Ludwig Institutiones Medicinæ Forensis; Meyer Institutiones Medico-Legales; Alberti Systema Jurisprudentiæ Medicæ; and Hebenstreit Anthropologia Forensis. There are many others of a later date, which, not to swell the catalogue, we shall omit; but we must mention an excellent collection of separate dissertations on this subject in six volumes, published from 1785 to 1790, by J. C. T. Schlegel at Leipsic. Many of these are inaugural dissertations, which, as we have had occasion to observe, are on the continent the works of the respective professors. We may, in addition to our remarks on the importance of this subject in other countries, add, from the title of the work before us, that it is taught by a distinct professor; and, had we transcribed all Dr. Mahon's titles, it would be seen