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not interfere with the result, and other metals, besides antimony and tin, cannot very well occur.(Compare H. Rose, Pharm. Centralblatt, 1853, p. 593, and Handbuch der analytischen Chemie).
$ 35. The reduction of sulphide of arsenic and arsenates, by means of cyanide of potassium, may very conveniently, and in a very simple manner, be executed in a glass-tube, as represented in Fig. 8.
The arsenical mass, after having been perfectiy dried, is placed in the bulb, and the pulverized and dessicated mixture of cyanide of potassium and carbonate. of soda added. The bulb must not be more than about half full. The narrow part of the tube is then carefully cleaned by means of some blotting-paper, wrapped round a knitting-needle. Heat is next applied to the bulb, just sufficient to drive out the last trace of water, which escapes and is removed with blotting-paper. When the narrow portion of the tube appears perfectly dry and clean, and has become sufficiently cool, the temperature of the bulb is raised to cause fusion of its contents; this temperature is kept up for some time. The reduced arsenic sublimes, and forins in the narrow part of the tube a mirror of great purity, provided the tube was carefully cleaned and dried. (Fig. 9).
I recommend to increase the heat, towards the end of the operation, by means of the blow-pipe, when a very excellent arsenic-mirror will be obtained. In case one should be disinclined to use sulphide of arsenic for this reduction, the residue contained in the porcelain dish ( 33), and which is free from nitric acid, may be saturated with lime-water, instead of carbonate of soda, when, on evaporation, a pulvernlent lime-salt is obtained, which mixes very easily with cyanide of potassium and carbonate of soda.
The reason why Fresenius and Babo did not recommend this simple method of reduction is very apparent. The volatilization of the arsenic takes place, in this case, in atmospheric air, and traces of the metal may, therefore, escape detection, in consequence of oxidation. Hence, the use of the above described apparatus, where the volatilization of the arsenic is effected in a current of carbonic acid gas. A better success might, perhaps, be secured by adding a small quantity of a body which affords carbonico acid, ex. gr. carbonate of lime.
§ 36. We now come to the third of the cases enumerated in $ 3.
Experiments, conducted by Orfila, Meurer, and other chemists, have shown that arsenic, when introduced into the stomach, is absorbed and carried by the blood into most other parts of the body, where its presence may be detected even if it can no longer be found in the stomach and the intestines. Meurer and Prinz a
gave to a horse half a drachm of white arsenic daily, in the shape of a bolus; four such doses were given, and thirty hours after the application of the last dose, the horse was killed.
No symptoms of poisoning had shown themselves,
and not a trace of arsenic was found in the stomach; but the poison was detected in the blood, in the urine, and in the liver of the animal.
It is, therefore, required, in cases of suspected poisoning, to analyze, if necessary, the urine, the blood, the liver, the bile; and other liquid and solid portions of the body, since it is quite possible that, after removal of the greater part of the poison by vomiting and purging, the rest may have passed from the primæ viæ by absorption into the liquid and solid portions of the body.
The urine may be acidulated with hydrochloric acid, either without further preparation, or after having been concentrated by evaporation, and then treated with sulphureted hydrogen, as described $ 10. Or it may be evaporated to dryness, and the residue be treated with hydrochloric acid and chlorate of potassa, as described 8.9.
The blood and the organs, as liver, kidneys, etc., (the latter after having been cut into small pieces), are also treated with hydrochloric acid and chlorate of potassa, to effect as complete as possible a destruction of the organic matters, and the resulting liquid is subjected to the same processes as those given for the examination of the contents, food, etc., in the second case.
$ 37. The chemico-legal examination is, in the highest degree, laborious and disgusting, when the body to be examined has been interred for months or years, and has passed into a state of putrefaction. In such a case, it is frequently no longer possible to distinguish or separate individual organs, and the analyst is then necessitated to examine the whole mass of putrefied organs, or the whole of the soft parts which dry up under some particular local circumstances, and even the bones. When this is the case, the body should not be laid in a bath of chlorine-water, or solution of chloride of lime, in order to destroy the offensive odor, since arsenic may thereby be extracted and lost. If chlorine-gas is employed to disinfect the body, it must be evolved by means of distilled sulphuric acid, free from arsenic. All soft parts, especially those which may have formed parts of the abdominal viscera, are carefully separated from the bones, and treated with hydrochloric acid and chlorate of potassa, as in the second case.—( Wöhler and Von Siebold).
$ 38. The following is another convenient process, given by Wöhler and Von Siebold, much to be prepreferred for the treatment of bodies which have been exhumed entire after some month's interment.
The entire soft parts are treated, in a large dish of genuine porcelain, with moderately strong nitric acid, which has been previously tested for arsenic; the dish is then heated upon a sand-bath, and its contents well-stirred, until the organic matters are so far destroyed and dissolved as to form a homogeneous pasty mixture. This is now neutralized with a solution of pure hydrate or carbonate of potassa, and about as much finely-powdered nitre (previously tested) added, as is equal in weight to the soft parts. The whole is now evaporated to dryness, with constant stirring, and the dry mass introduced by de
grees, in small portions, into a new clean Hessian crucible, heated to dull redness. In this manner,
the whole of the organic matter is burnt, and the
arsenic, if present, converted into arsenate of potassa. In this process, it is important, and not very easy, to add the proper quantity of nitre. If too little nitre is employed, part of the organic matter may remain unburnt, and arsenic may be volatilized from the carbonaceous mass; on the other hand, too much nitre would interfere with the subsequent treatment of the mass. It is better to make a preliminary test with a small portion of the mixture, by introducing it into a small red-hot crucible, and observing whether the mass is perfectly white after deflagration. If it is black and carbonaceous, more nitre must be added.
The mass, which now consists essentially of carbonate, nitrate, and nitrite of potassa, and may, also, contain arsenate of potassa, is dissolved in the smallest possible quantity of boiling water, and the solution, without filtering off from the suspended phosphate of lime and silica, gradually mixed, in a porcelain dish, with a slight excess of sulphuric acid. The pasty saline mass, thus produced, is carefully heated till all the nitric and nitrous acid is expelled, a point to which great attention must be paid. On cooling, the mass is stirred up with a little cold water, and the solution poured off from the large deposit of sulphate of potassa. The latter is washed several times with cold water, the washings mixed with the first solution, the liquid boiled with sulphurous acid, and sulphureted hydrogen gas passed through it for several days, while, from time to time, a gentle heat is applied. The subsequent operations are the same as
as) in the second case.
$ 39. For the sake of completeness, the following