In Paris, arsenic forms the basis of several blistering cerates. Such applications cannot be safe.
[404]. This substance may be considered as consisting of charcoal, in a state of extremely minute division, and the sub-carbonate of potass. It is prepared by deflagrating, in a crucible, two parts of Super-tartrate of Potass with one part of Nitrate of Potass.
[405]. In order to close the end of the tube, where a blow-pipe is not to be procured, the end is to be placed in a common fire, until it is completely softened, and a pair of small tongs being at the same time made red hot, the tube is to be withdrawn from the fire, and then heated and pinched by the tongs, and at the same time bent up at an acute angle, so as to be brought parallel to the body of the tube. The tube is then to be heated a second time, and being again firmly pinched by the hot tongs, the end will be found to be completely impervious. Where a glass is not at hand Mr. R. Phillips says a common draught phial may be made to answer the purpose, especially a ten drachm phial, for it is long in proportion to its diameter. In using it, however, care must be taken that the suspected powder and black flux do not reach the bottom, for, on account of its thickness, it will readily break on the application of heat. The phial must therefore be heated laterally by means of a spirit lamp.
[406]. Dr. Bostock has informed us that the best proportions for this coating are one part of common pipe clay, to three parts of fine sand; which are to be well kneaded together, and reduced to such a state of tenacity that the lute will readily adhere to the tube, and its different parts unite, without forming a visible seam, (Edinb. Med. & Surg. Journ. April, 1809.)
[407]. Should the operator be unable to procure a spirit lamp, a very convenient substitute may be provided in the following manner. Let a piece of tin plate, about an inch long, be coiled up into a cylinder of about ⅜ths of an inch in diameter, and, if the edges be well hammered, it is not necessary to use solder. Perforate a cork, previously fitted to a phial, and put a cotton wick through the short tin tube, and the tube through the cork. The lamp is now complete, and will afford a strong flame, taking care of course not to prevent the rise of the spirit by fitting the cork too closely.
[408]. In the celebrated case of Kesler, who was tried in the state of New-York some few years ago, for having poisoned his wife with arsenic, this very question was agitated, and gave rise to much learned controversy. The physicians originally called to examine the body of the deceased, found, on dissection, the stomach and intestines highly inflamed, and on the inner surface of the stomach, particles of a vitreous appearance. These particles were subjected to various chemical tests, all of which very strikingly concurred in confirming the suspicion that they were arsenic. Upon this, in connexion with the other testimony adduced in the case, the prisoner was found guilty and condemned to death. The minutes of the trial were transmitted by the presiding judge (Yates) to Governor Clinton, who submitted the professional part of them to Dr. M‘Nevin of New-York, for his opinion in relation to it. Thus called upon, Dr. M. seems to have considered that his only duty was to find fault. Objections were accordingly raised against every test hitherto employed by the best chemists for the detection of arsenic. They were all pronounced to be uncertain, and “the only thing to be relied on,” according to him, was “the exhibition of the metal itself in its metallic lustre and state.” In consequence of this difference of opinion, the execution of Kesler was suspended by the Governor, and the whole case referred by him to the Legislature. That distinguished body appointed a committee to investigate the business, and the result was that the original verdict of the jury was confirmed by the Legislature, and the criminal was executed. It must furnish a source of the purest gratification to the medical witnesses concerned in this case, to find their opinions so unequivocally and so justly confirmed by an authority so high as Dr. Paris. For a detailed account of this trial we refer to Beck’s Medical Jurisprudence, vol. 2, p. 239.—Ed.
[409]. If any trifling opacity occur in a simple solution of arsenic, when assayed by the nitrate of silver, it may be considered as the effects of some casual impurities; this is further demonstrated by bringing over the surface of the arsenical liquid, a piece of blotting paper, or a stopper, moistened with a solution of ammonia, when there will instantly form a copious yellow precipitate of arsenite of silver. If this experiment be performed on a surface of glass, laid over white paper, the result is very striking and beautiful.
[410]. Annals of Philosophy, vol. x, p. 60.
[411]. London Medical and Physical Journal, January, 1818.
[412]. In Wine and Porter, the solvent is probably Tartaric acid, for the Arsenite of Silver is soluble in this as well as in the acetic and nitric acids. In Tea the solvent would appear to be Tannin. The Arsenite of Silver is likewise dissolved by the Tartaric acid, and also, but not so readily, by the Citric and Acetic acids.