DETECTION OF ANTIMONY.
Strictly speaking the salts of antimony are more therapeutic than poisonous in their action. In fact they usually act as emetics and, under certain circumstances, may be taken in large doses without incurring serious results. There are instances, however, in which their action is truly toxical, and it becomes necessary to effect their detection in the organs of a body. It should be remarked that these salts, if absorbed, remain by a kind of predilection in the liver and spleen. A special examination of these organs should therefore be instituted, particularly if the fluids of the alimentary canal are not at hand, which is frequently the case when some time has elapsed before the investigation is undertaken.
The remarks made in the preceding article concerning the distinctive properties of arsenic and antimony need not be repeated here. The search for antimony is likewise executed by aid of Marsh's apparatus. We will confine ourselves to a description of a modification to this apparatus proposed by MM. Flandin and Danger, and employed in the separation of antimony and arsenic, when a mixture of these metals is under examination. Another process, by means of which we arrive at the same result with greater certainty and by the use of a less expensive apparatus, will then be mentioned. We will, however, first indicate the preferable method of destruction of the organic substances.
Were the decomposition performed by means of sulphuric acid, sulphate of antimony, a slightly soluble salt and one not well adapted to the subsequent treatment with nascent hydrogen, would be formed. In order to obtain the metal in a soluble state, the formation of a double tartrate of antimony and soda is desirable. This may be accomplished in the following manner:
1. A cold mixture of nitrate of soda, sulphuric acid, and the suspected materials is prepared in the proportion of 25 grammes of the nitrate to 39 grammes of the acid, and 100 grammes of the substance under examination. This mixture is heated and evaporated to dryness, and the decomposition of the organic matter completed in the usual manner. The carbonaceous residue obtained is pulverized, and then boiled with a solution of tartaric acid. By this treatment the antimonate of soda present is converted into a double tartrate of antimony and soda, which is easily soluble in water. The solution is filtered and then introduced into Marsh's apparatus.
2. Another method consists in heating the substances under examination with one half of their weight of hydrochloric acid for six hours on a sand-bath, avoiding boiling. The temperature is then increased until the liquid is in a state of ebullition, and 15 to 20 grammes of chlorate of potassa, for every 100 grammes of the suspected matter taken, added in successive portions, so that a quarter of an hour is required for the operation. The liquid is next filtered, and the resinous matter remaining on the filter well washed with distilled water; the washings being added to the principal solution. A strip of polished tin is then immersed in the liquid: in presence of a large amount of antimony the tin becomes covered with a black incrustation: if but a minute quantity of the metal is contained, only a few blackish spots are perceptible. After the tin has remained immersed for 24 hours, it is withdrawn and placed in a flask together with an amount of hydrochloric acid sufficient for its solution in the cold. If, after several hours, blackish particles are still observed floating in the liquid, they can be dissolved in a few drops of aqua regia. The solution may then be directly introduced into Marsh's apparatus.
APPARATUS PROPOSED BY FLANDIN AND DANGER.
Fig. 7.
This apparatus consists of a wide necked jar A (Fig. 7) for the generation of the gas, the mouth of which is closed with a cork having two openings. The safety tube S, which is funnel-shaped at its upper extremity and has its lower end drawn out to a point, passes through one of these apertures; the other opening contains the small delivery tube B, open at both ends, and terminating in a point at its upper extremity: it is also provided with lateral openings, in order to prevent the solution being carried up to the flame. The second part of the apparatus is the condenser C, 0.03 metre in diameter, and 0.25 metre in length. This terminates at its lower extremity with a cone, and connects at the side with the tube T, slanting slightly downwards. In the interior of the condenser, the cooler E is contained, the lower end of which is nearly in contact with the sides of the opening O. The combustion tube D, 0.01 metre in diameter, is connected by means of a cork with the tube T; it is bent at right angles, and encloses the tube B, in such a manner as to allow the evolved gas to burn in its interior. The dish F is placed beneath the opening O. If the gas which burns in the combustion tube contains arsenetted hydrogen, water and arsenious acid are produced. A portion of this acid is retained in the tube D, the remainder is carried over, with the aqueous vapor, into C, where it condenses, and finally falls into the dish F. Both portions are subsequently examined by means of reactions necessary to establish the presence of the acid. If the ignited gas contains antimonetted hydrogen, water and an intermediate oxide of antimony are formed. The latter compound is entirely retained in the tube D separated from the greater part of the arsenious acid, if this body be present, and can be brought into solution by means of a mixture of hydrochloric and tartaric acids. A fluid is then obtained which can be introduced into Marsh's apparatus, or otherwise examined for antimony.
NAQUET'S APPARATUS.
Fig. 8.
Although the separation of arsenic from antimony is the chief object in making use of the apparatus proposed by Flandin and Danger, it is evident that this result is not fully accomplished, since a small portion of arsenious acid remains in the tube D (Fig. 7), together with the intermediate oxide of antimony. The following method secures the complete separation of these metals: An amalgam of sodium and mercury is introduced into the flask A, (Fig. 8), which is provided with two openings. The tube B, terminating in a funnel at its upper extremity, passes through one of these orifices. The other aperture contains a cork enclosing the small tube C, which is bent at a right angle and communicates, by means of a cork, with the larger tube D filled with cotton or asbestus. A set of Liebig's bulbs, E, containing a solution of nitrate of silver, is attached to the other extremity of this tube. The apparatus being mounted, the solution under examination is slightly acidulated and introduced by means of the tube B into the flask A: the disengagement of gas begins immediately. If arsenic and antimony are contained in the solution, arsenetted hydrogen and antimonetted hydrogen are evolved. Both gases are decomposed in passing through the solution of nitrate of silver contained in the Liebig bulbs: the arsenetted hydrogen causes a precipitation of metallic silver, all the arsenic remaining in solution as arsenious acid; the antimonetted hydrogen is decomposed into insoluble antimonate of silver. After the operation has continued for several hours, the apparatus is taken apart, the nitrate of silver solution thrown on a filter, and the precipitate thoroughly washed. An excess of hydrochloric acid is then added to the filtrate, and the precipitate formed separated from the solution by filtration, and well washed. The wash-water is added to the solution, and the whole then examined for arsenic by means of Marsh's test.
The precipitate formed in the nitrate of silver solution, which contains antimonate of silver, is well dried, mixed with a mixture of carbonate and nitrate of soda, and calcined in a porcelain crucible for about three-quarters of an hour. The crucible is then removed from the fire, and the cooled mass treated with hydrochloric acid until a drop of the filtered fluid ceases to give a residue when evaporated upon a watch-glass to dryness. A current of sulphurous acid is now conducted through the filtered solution until the odor of this gas remains persistent. The excess of acid is then removed by boiling, and the solution placed in Marsh's apparatus and tested for antimony.
DETECTION OF MERCURY.
If a mercurial salt exists in a considerable quantity in the substances extracted from the alimentary canal, or ejected either by stools or vomiting, it can be isolated by treating these materials with water, filtering the liquid, and evaporating the filtrate to dryness. The residual mass is taken up with alcohol, and the solution again filtered and evaporated. Upon dissolving the residue obtained by this operation in ether and filtering and evaporating the solution, a residue is obtained which when dissolved in water forms a fluid wherein the presence of mercury can be detected by means of the ordinary tests.
When, however, only a minute quantity of mercury is present, and this has been absorbed, its detection is more difficult. It will be necessary under these circumstances to make use of either Smithson's pile or Flandin and Danger's apparatus.
SMITHSON'S PILE.
Smithson's pile consists of a small plate of copper around which a piece of thin gold foil is wrapped. This is immersed in the solution to be tested for mercury, which has previously been slightly acidulated: if mercury be present, the plate acquires a white color which disappears upon exposure to the flame of a spirit-lamp. A similar reaction occurs in presence of tin, as this metal would likewise be deposited upon the plate, and, upon heating, would penetrate the metal and restore to it its natural color. The danger of mistake arising from this fact is obviated by introducing the copper plate into a tube closed at one end and bent at a right angle. The open extremity of the tube is drawn out to a fine point and immersed in water contained in a second tube also closed at one end. Upon heating the plate in the flame of an alcohol lamp, the white color disappears if produced by mercury, and at the same time this metal condenses in the narrow extremity of the tube. The metallic globules formed can be recognized either by the naked eye or with the aid of a lens, or by rubbing them with a piece of gold foil when the latter will acquire a white coating.
When Smithson's pile is employed, the organic substances are most advantageously decomposed by means of chlorine. It is advisable to operate with as small a quantity of fluid as possible, for, owing to the volatility of bichloride of mercury, a portion of this salt may be lost by the evaporation of aqueous, alcoholic, and even etherial solutions, and the detection of minute quantities rendered impossible.
APPARATUS PROPOSED BY FLANDIN AND DANGER.
Fig. 9.
This apparatus consists of a stand S, (Fig. 9) supporting a balloon A, which serves as the reservoir of the suspected solution, and a funnel B, into which the neck of the balloon is dipped. The funnel B is bent at a right angle and is drawn out at its lower end under which the dish C is placed for the reception of the escaping fluids. A fine wire of pure gold, forming the negative electrode of a Bunsen's battery, passes through the lower extremity of the funnel. The end of this wire nearly comes in contact with a second wire, inserted in the upper part of the funnel, and connected with the positive pole of the battery. If the balloon filled with the solution is inverted and immersed in the funnel B, its neck will be submerged at first; soon, however, it becomes uncovered, owing to the depression of the level of the fluid caused by the escape of the latter through the tapering extremity of the funnel: a bubble of air then passes in the balloon and expels a drop of the solution. This process is repeated at short intervals, causing a continuous flow of the fluid, the rapidity of which is easily regulated by elevating or lowering the balloon, thus raising or depressing the level of the liquid. The apparatus having been mounted in this manner and the battery set in action, the disengagement of gas commences. Should mercury be contained in the solution under examination, this metal will be deposited upon the negative wire. When the operation is completed this wire is detached from the apparatus, washed with ether, and dried. It is then introduced into a small tube provided with a bulb, and the mercury volatilized by means of the blow pipe flame: the metal condenses in the bulb of the tube in globules which are readily recognized. They can also be dissolved in nitric acid, and the presence of a mercurial salt in the solution confirmed by further tests.
The solution to be examined in the preceding apparatus, is prepared as follows:
The suspected organic matter is treated with cold sulphuric acid of 66° B. until liquefied, and hypochlorite of lime, and distilled water then added: if necessary, the evolution of chlorine can be accelerated by a further addition of sulphuric acid. As soon as the liquid becomes clear, it is filtered, concentrated and examined as described above. The solution contains the mercury in the state of bichloride, a salt soluble in water and well adapted to the above test.
The substitution of a large balloon, having a capacity of about 2 litres, in place of the small vessel of Flandin and Danger's apparatus, is to be recommended as doing away with the necessity of evaporation; an operation which invariably causes a loss of substance. The apparatus, modified in this manner, is the most delicate in use for the detection of mercury.