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path, of that city. The elaborate paper read by this gentleman was remarkable for the display of information, acute perception, and decisive experiment. As Mr. Herapath was acquainted with the process of Mr. Marsh, he describes it to be "one of the most elegant that can be conceived; at the same time that it is one of the most sensitive." When we consider the time, the place, the speaker, and the audience he was addressing, it is scarcely possible to imagine a higher or more gratifying eulogium. Many of Mr. Herapath's own remarks were too valuable not to be preserved. Among others he observed that:

Arsenical poisons are obtained with so much facility, and their operation is so deadly, that they are the principal means resorted to by secret poisoners. It becomes, therefore, essential to the safety of the community, that every new fact relating to their administration, operation, or detection, should be made known. Few, if any well-authenticated cases have been published in which death was occasioned by realgar, or red arsenic, but the Burdock case was one of this kind. It will, perhaps, be remembered that the victim, Mrs. Smith, had been buried fourteen months; that upon exhumation orpiment was found in the stomach, and the body was partly converted into adipocere*. In prosecuting his experiments in this case, he conceived the idea of identifying the poison found with that sold to the witness Evans, by Hobbs, the druggist, by means of an impurity he discovered in the poison of the stomach. With this view he purchased some out of the same box, and requested that it might be of the same kind as that sold the prisoner's agent. It then transpired that the box contained three different substances mixed together: white, yellow, and red arsenic; the two former in small lumps, the latter in powder; and that it was the powder of realgar only which had been administered, although it was undoubtedly found as yellow orpiment in the exhumed body. In tracing the possibility of change, he found that two agents,-sulphuretted hydrogen and ammonia, would either of them, convert realgar into orpiment. Now, as it was well known, that both of these gases were evolved during putrid de· composition, there could be no difficulty in accounting for the change of colour. But to place the matter beyond all doubt, he made a direct experiment by poisoning an animal with realgar, and found that after putrefaction it became changed, as in the case of Mrs. Smith. It would, perhaps, be recollected, that the conviction of the prisoner was mainly owing to the evidence of a little girl, who deposed that she saw Mrs. Burdock put a powder into some gruel, and afterwards administer it to Mrs. Smith. At the time considerable doubt was entertained of the truth of her evidence, from its being invariably precise, even to a word; and also from the difficulty of believing that any person would be found so fool-hardy as to mix and administer poison before a child, and that child a stranger. But what he had stated, proved to demonstration that her evidence was correct, for she said the gruel given was of a nasty red colour;" a colour she could not have had an idea of, unless she had seen it, as nothing had transpired of red arsenic; and had she invented a tale to account for the appearance of the body, or had she spoken from Adipocere animal matter converted spontaneously into a substance considerably resembling spermaceti.

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what she had heard from others, she would have deposed to its being of a yellow colour.

From what had occurred, therefore, it was clear, that the realgar of the shops would cause death. That half an ounce, given at twice (by the prisoner's confession), was sufficient for that purpose. That realgar became orpiment during putrefaction. That realgar, like arsenious acid, had a tendency to control putrefaction, and convert bodies into adipocere. During the experiments upon this case, he found that the microscopic system of testing, which was first introduced by Dr. Wollaston, and which he (Mr. H.) constantly followed, could be made to improve the very beautiful reducing process proposed by Dr. Christison; and also furnished an excellent method of proving to the jury the presence of arsenic. He would suppose that the whole of the organic matter had been decomposed, as he did it, in boiling nitro-muriatic acid; that potash had been added in excess to prevent the injurious effects of mineral acid upon sulphuretted hydrogen; and that then a slight excess of acetic acid had been poured in, and the sulphuret of arsenic precipitated; if this were reduced to the metallic state in Berzelius's tube, and then oxidized, as recommended by Christison, it was in the state in which, in subsequent experiments, his modification of Dr. Wollaston's practice was beneficial. Instead of putting the few drops of solution of arsenious acid, thus obtained, into test-tubes to apply the re-agents, he used a china tablet, and having applied a drop of the solution, and then a little ammoniacal sulphate of copper, the green of Scheele became evident, from the contrast of colour with the white plate; but even that might be improved by guiding the coloured drop by means of a glass rod down upon a piece of white blotting-paper, previously placed on a flat chalk-stone, which, by absorbing the solution, removed any excess of the blue re-agent, which was always liable to overpower the colour of Scheele's green, while it left the latter on the paper; when dried it could be introduced, as he usually did it, into a sealed tube, which could be marked with a diamond in the hand-writing of the experimenter, ready for identification before a jury. He felt satisfied that 1-10,000th of a grain of arsenious acid might be rendered evident by this means. The other two re-agents, ammoniacal nitrate of silver and sulphuretted hydrogen, could be applied upon the plate in the same way, and when dried could be similarly enclosed. In all cases where a highly oxygenating process was followed,for instance, where the mixture was boiled in nitro-muriatic acid, or where deflagration with nitre was practised,-the arsenical compound was converted into arsenic acid, and in passing sulphuretted hydrogen (after the usual precautions), the first portion of the gas was decomposed by giving hydrogen to the oxygen of the arsenic acid; consequently sulphur fell mixed with sulphuret of arsenic, but so extremely light that it took some hours to deposit; after which the mixed deposit could be collected together, and, upon reducing it to metallic arsenic, the sulphur would be separated: for, from being more volatile, it was found above the crust of metal, and in the oxidizing operation it formed sulphurous acid, and disappeared while the arsenious acid condensed.

It sometimes happened that arsenic was contained in substances which prevented the ordinary processes from being followed; for instance,

in the case of Sophia Edney, who was convicted at the March assizes, at Taunton, of poisoning her husband. He had found about one-eighth of a grain in the duodenum (the contents of the stomach had been thrown - away by the surgeon who examined the body, under the belief that an ulcer found in the stomach was sufficient to account for death): the only other matters brought to him for examination were a few grains of bacon fat scraped from the bottom of a frying-pan. In the fat he could find no arsenic, and the potato being an amylaceous* substance it was in vain to try the usual re-agents, or to make a filtered solution. He therefore projected it into melted nitre; when it was deflagrated, diluted acetic acid was added until the carbonate of potash, proceeding from the deflagration, was supersaturated. Sulphuretted hydrogen turned it yellow, and upon deposition and subsequent treatment in the way he had alluded to before, he obtained enough to take to a jury specimens of the reduced metal of arsenious acid; Scheele's green, arsenite of silver, and orpiment, were made from it, although he felt satisfied that the reduced arsenic was not more than 1-100th of a grain. It had been said by the dying man that his wife had fried potatoes in this pan for him, and he had not been well since. The prisoner's witness proved that the pan had subsequently been wiped and used to fry bacon, which had been eaten with impunity by two persons, exclusive of the prisoner, who had herself" eaten a bit as big as a nut;" yet, enough had been left adhering to the pan to prove her guilt, which her confession ultimately acknowledged.

Although nitre afforded an excellent means of removing all organic matter, and thus leaving the operator free from all embarrassment, yet it could not be depended on for a quantitative analysis, as a certain proportion is volatilized during the process; this loss might be reduced by putting a little nitre in the solution before evaporating to dryness.

The recent plan of discovering arsenious acid, by converting it into arsenuretted hydrogen, and deposing the arsenical crust during its combustion, is the most elegant that could be conceived: at the same time that it is the most sensitive; but it would require a few modifications to make it the best for exhibition to a jury. First, it was essential that the zinc used to procure hydrogen should have been treated by the experimenter in the same way without arsenic; otherwise the counsel would embarrass the witness by asking if he was certain that arsenic was not contained in the zinc; and next, the metallic crust should be so received as to be kept from atmospheric air, otherwise it would lose its lustre by passing into the "fly-powder" of the Germans. He had found it best to proceed thus:-instead of a plate of glass to cool the flame and receive the crust, he used one of mica, with three drops of water in separate places on one of its surfaces; if the flame was allowed to play under one of those drops, the evaporation of the water kept the part cool, and the crust was thicker, while the risk of fracture was avoided; then by inverting the plate and holding the drops in succession some little height over the flame, they became solutions of arsenious acid, and could be tested with three re-agents as before stated; and if it was necessary to make a quantitative experiment, the products of the flame could be condensed in a large globe, the arsenious acid dissolved and precipitated by sulphuAmylaceous, highly pulverized, starch-like.

*

retted hydrogen. The part of the plate of mica, containing the crust, should then be cut off, and introduced into glass tubes hermetically sealed up, like the slips of blotting-paper, containing the coloured results of the re-agents.

We think it scarcely possible, certainly not necessary for any practical purpose, that the processes of examination which have been detailed can ever be improved upon. Detection, or the most perfectly satisfactory proof of the non-existence of the poison, in all cases of inquiry, is now certain. Furnished with this unerring test, it may be said that in a country in which the inquest of the coroner is established, there can be no secret poisoning. And it may added, that if the knowledge of this test be universally disseminated there will probably be no attempts to commit this crime.

But valuable as this certain detection of the fact when committed is, the prevention of the mischief must be admitted to be still more so. The few precautions which our retail druggists make use of in their sale of poisons, are, no doubt, useful as far as they go, but they are notorious for their inefficiency. The following suggestions of MM. Chevallier and Boys de Loury, which these gentlemen lately submitted to the French Minister of Justice, with the humane intention of rendering the crime of poisoning less frequent, will, therefore, certainly deserve the attention of the learned corporations in this country, whose duty it is to watch over the interests of this branch of public safety; and we are confident that many of the individuals who dispense these deadly articles* to their fellow-creatures will adopt some of the suggestions, without waiting for the compulsory statute of the Hall or College.

M. Chevallier and his colleague are of opinion that poisoning would be rendered less frequent if it were required, by authority, that all poisonous substances should have either taste or colour communicated to them, except in the few cases where it might absolutely destroy their use in the arts.

That the white arsenic intended for steeping of corn, should be mixed with aloes in powder, in the proportion of ten parts aloes to ninety arsenic. That the arsenious acid used for external applications, by veterinary surgeons and farriers, and by others in their treatment of the itch, should be prepared in the same manner.

That the arsenious acid intended to poison rats, mice, &c., should be mixed with Prussian blue or soluble indigo, in the proportion of ninety parts acid to ten colouring-matter.

That the metallic arsenic in powder, sold for the destruction of flies, should be mixed with a tenth of its weight of soluble blue.

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If these precautions were universally adopted, it is highly probable that these gentlemen are correct in thinking, that in numerous cases taste imparted to food in which poisonous substances had been mingled, would be sufficient to warn the intended victims, and save them from the danger to which they were exposed; and that in other cases, colour so given might have a similar salutary effect."

* We are sure they will be appreciated | not suffer them on his premises, and who by, at least, one in the trade-we mean the has inscribed on his house in large chacautious druggist of Barnstaple, who will racters, "No OXALIC ACID SOLD HERE."

QUESTIONS FOR SOLUTION RELATING TO METEOROLOGY, HYDROGRAPHY, AND THE ART OF NAVIGATION,

BY M. ARAGO.

[Continued from p. 333, vol. I.]

THE springs of Aix, in Provence, have suggested to me a plan of experiment, of which I think it proper to insert a notice, as very probably the physical conditions on which it is founded may be met with in other places.

The town of Aix, in Provence, possesses baths of thermal water, known under the name of the Baths of Sextius. They are surrounded by an edifice, the building of which was completed in 1705. The spring was formerly so copious, that in the last two months of that same year, it was amply sufficient for the service of upwards of 1000 bathers. It fully supplied nine jets of a fountain, and nine baths. From the year 1707 the water began to be less plentiful, and in a few months was so much diminished, that the establishment was wholly abandoned.

Other warm springs exist in the town,—at the Cours, in the Garden of the Jacobins, at the Monastery of St. Bartholomew, at La Triperie, Grioulet, the Hotel de la Selle d'Or, the Hotel des Princes, &c., and at the bottom of certain wells, such as that belonging to Sieur Boufillon (at the corner of the Rue des Marchands), and some tanners' pits. These different springs diminished like that of Sextius, and even more rapidly. Many of them, and, among others, those of the Jacobins, of St. Bartholo→ mew, La Triperie, and Grioulet, dried up entirely.

During the period that this diminution of many of the springs of Aix, and the entire destruction of some of them, was going on, individuals began to turn to their private advantage some very copious springs, which they discovered by digging to a small depth in properties situated a little distance from the town, in the territory of Barret. The idea that these new waters were precisely the former waters of the town soon occurred to the minds of many persons; but the impossibility of decisively proving that such was the fact, for a long time prevented the authorities from interfering. At last, in 1721, during the dreadful plague that prevailed in Provence, Dr. Chicoineau of Montpellier, having thought it expedient to order baths for the persons detained in quarantine, Vauvenargues, the commandant of Aix, came to the following resolution: "As the warm baths of the town of Aix appear to us necessary to wash and purify the convalescent patients in quarantine, and the said baths have not sufficient water for this purpose, on account of the quantity that has been withdrawn from the source by various proprietors near it, we order, for the good of the service, that steps be immediately taken to prevent this," &c. &c. In virtue of this order, the consuls caused the holes dug in the district of Barret to be filled up, and, in twenty-two days after this operation, the waters of the Baths of Sextius were augmented three-fourths, and many springs which had become entirely dry, that of Grioulet for example, again began to flow.

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