tially decomposed on distillation. After several distillations a small quantity of a body was isolated, which contained arsenious, but no arsenic acid, and which proved to be an impure arsenious ether. It is evident from these results that, at the temperature required for the action of arsenic acid upon the silicate of ethyl, the greater part of the product is decomposed with formation of common ether and ethylene, while a small quantity of the arsenic acid is reduced and arsenite of ethyl is formed, and that the reaction does not furnish any arseniate of ethyl.

The arseniate of ethyl can be easily prepared by the action of the iodid of ethyl on the arseniate of silver

зC2HI+Ag ̧AsO4=3AgI+(С2H5),A§О4.

When the two bodies, mixed with pure anhydrous ether are heated together at about 90° in a sealed tube, the reaction is completed in a few hours, and the point at which this takes place is marked by the change of color of the silver salt from red to light yellow. It is important that the arseniate of silver should be in excess and that the temperature should not exceed 100°, as the iodid of ethyl decomposes a portion of the arseniate of ethyl, and the decomposition takes place more readily, the larger the quantity of iodid and the higher the temperature.

The liquid together with the iodid of silver is taken from the tube and washed with pure ether until it is entirely freed from arseniate of ethyl. This operation can be most conveniently performed on a funnel, provided with a glass plate ground to fit it. A hole should be drilled in the plate, and a funnel tube ground into it, in order that the liquid may be poured upon the filter without removing the glass plate.

The solution in ether is distilled and finally heated in a water-bath, while a current of dry air is passed through it to carry off the last trace of ether. The arseniate of ethyl thus obtained can be most easily purified by distillation in a partial vacuum, as it is decomposed in part by distillation in the air. In operations of this kind it is preferable to distil under a diminished pressure rather than to push the exhaustion of the air as far as possible since the boiling point remains more constant, when the pressure is high. This probably is due in great part to the fact, that a slight variation of pressure does not alter the relative pressure so much, when the exhaustion is incomplete, as when it is nearly complete. For instance, the pressure may well vary 2 millimeters during the course of a distillation, and a variation from 5 to 7 millimeters affects the boiling point much more than a variation from 200 to 202 millimeters.

In the case of the arseniate of ethyl it was found that it distilled under a pressure of 60 millimeters at about 85° lower than in the air, and that this difference of temperature was sufficient

to prevent decomposition. The distilling apparatus was provided with an air reservoir and with a mercury guage, and the pressure was kept nearly constant at 60 millimeters during the course of the distillation.

Arseniate of ethyl distils at 148°-150° under a pressure of

60 millimeters.

About of the theoretical quantity are obtained by the above method of preparation.

The arsenic ethers are immediately decomposed by smallest traces of water and it is essential that the common ether used in their preparation should be absolutely anhydrous. It is also important for the operation in the sealed tube, that it should contain no alcohol, since the iodid of ethyl acts upon alcohol with formation of ordinary ether and water. Ether can be most easily freed from small quantities of water and alcohol by digesting it several times with shavings of sodium, which can be cut with a knife from a large piece, allowing it to stand each time 24 hours with the sodium, and then distilling. Ether so prepared can be heated with sodium to 90° in a sealed tube without the smallest evolution of hydrogen.

The following analyses were made of arseniate of ethyl distilling at 148°-150° under a pressure of 60 millimeters.

2

I. Substance = 0.2980 grms.; CO, = 0·3470 grms.; H20 = 0.1740 grms.

II. Substance = 0.9260 grms. ; arseniate of magnesium and ammonium = 0.7705 grms.

The determination of arsenic was made by decomposing a weighed quantity of the arseniate of ethyl by water, evaporating with nitric acid, and determining the arsenic acid as the arseniate of magnesium and ammonium on a weighed filter. Calculated for (C2H.), AsO, 31.86

I.

C =31·79

H= 6.49

As ...

II.

32.85

6.64

33.18

The density of liquid arseniate of ethyl at 0° compared with that of water at 4°=1.3264. Its density at 8.8°-1.3161. The density of vapor of arseniate of ethyl can not be taken on account of its decomposition by heat. This decomposition, however, is not so great, but that its boiling point in the air can be determined with sufficient accuracy. When a portion of the arseniate of ethyl, which has been purified by distillation under a diminished pressure, is distilled in the air, the greater part of it passes at 235°-238°, but toward the last part of the distillation decomposition ensues, and a white frothy deposit of arsenic acid is left in the retort.

Arseniate of ethyl attracts moisture from the air and is immediately decomposed with formation of arsenic acid and al

cohol. It dissolves immediately in water, undergoing the same decomposition. Particular attention was paid to the question of the existence of ethyl-arseniates, and experiments were made under the most favorable conditions for observing their formation, but thus far with negative results. Felix D'Arcet, (Ann. Chem. und Pharm., xix, p. 202), gives the analysis of the barium salt of the di-ethyl arsenic acid Ba(C,H,), (AsO1),; but Hugo Schiff (Ann. Chem. und Pharm., cxi, p. 370,) failed to obtain this body on dissolving arsenic acid in alcohol, evaporating until the solution acquired the consistency of a syrup, dissolving in water and neutralizing with baric carbonate. This result

proves at least that no ethyl arsenic acid can exist in aqueous solution, and my own experiments confirm those of Mr. Schiff. It appeared possible that when the arseniate of ethyl is decomposed by water, the decomposition might pass through two stages, and that ethyl arsenic acids might at least exist for a time in the aqueous solution, even though they were ultimately completely destroyed. In order to test this idea, a weighed quantity of arseniate of ethyl was dissolved in water, litmus solution was added and it was neutralized immediately with a standard solution of ammonia. If the decomposition with water had been a gradual one with formation of the acids mentioned, the neutralized solution should have developed an acid reaction after the lapse of a considerable time. This was not the case. The same amount of ammonia was required for neutralization, either immediately, or after the solution had stood 24 hours, and moreover, the reaction was exactly similar to that of a corresponding quantity of pure arsenic acid dissolved in water. It should be noticed that no sharp change of color can be obtained by neutralizing a solution of arsenic acid containing litmus with ammonia.

Another attempt was made to obtain the ethyl arsenic acid in an alcoholic solution. Pure arseniate of ethyl was mixed with alcohol, and only enough aqueous alcohol was added to furnish water for the decomposition expressed by the reaction:

4

(C2H,), AsO,+H2O = H(C2H ̧), AsО ̧+C2H ̧O; and the mixture was distilled in vacuo. It behaved exactly like a solution of arsenic acid in arseniate of ethyl: the latter distilling and leaving the anhydrous arsenic acid as a residue. It was thought probable that in this experiment the first product of the action of water would enter into the following reaction with some of the undecomposed arseniate of ethyl:

2 7

H(C,H,), AsO,+(С,H ̧), AsО ̧=(C,H,), As,O,+C2H ̧O; but no condensed ether like the one whose formula is given was obtained, and the only result of the decomposition with aqueous alcohol under these circumstances is the setting free of arsenic acid and alcohol.

Arseniate of ethyl is immediately decomposed by ammonia with the formation of a crystalline body, which it is very difficult to obtain pure on account of the extreme avidity with which it absorbs moisture. The results of several analyses lead to the conclusion, that the body which is first formed has the composition: (C,H,), NH, ASO,, and that it absorbs water to form a di-ethyl arseniate of ammonium, (C,H,),NH,AsО, but the study of this product is not yet completed.

ARSENIATE OF METHYL.

The arseniate of methyl can be prepared from the iodid of methyl and arseniate of silver in the same way that the arseniate of ethyl is prepared. The crude product is purified by distillation under a pressure of sixty millimeters. At this pressure it distils without decomposition at 128°-130°.

I. Substance 0.4500 grms.; CO2=0·3285 grms.; H2O=0·1980 grms.

II. Substance=0.8070 grms.; As2O, 0·4966 grms.

The determination of arsenic was made by decomposing the ether with water, evaporating with nitric acid, and heating the arsenic acid thus formed with oxyd of lead.

The density of liquid of arseniate of methyl at 14°.5, compared with water at 4°, 1.5591.

When pure arseniate of methyl is distilled in the air, the greater part passes at 213°-215°, but there is a partial decomposition with separation of arsenic acid.

It resembles the arseniate of ethyl in all its properties. It is a colorless liquid, miscible in all proportions with water, and it is decomposed immediately into arsenic acid and alcohol by the action of water or moisture for the air.

ARSENIATE OF AMYL.

This body is produced by action of iodid of amyl on the arseniate of silver, but it cannot be obtained in a state of purity, because it decomposes, even when distilled in vacuo.

The crude product of the reaction, after having been heated to 170°, was mixed with pure ether, when a considerable quantity of arsenious acid was precipitated; after filtering, the solution was heated in an oil-bath, and finally a current of dry air was passed through it, while the bath was kept at 200°. An analysis of the product so obtained gave C=39.31 per cent and H=7.64 per cent, instead of C=51·14 per cent and H=937 per cent.

A somewhat better result was obtained by distilling the crude product in vacuo. The greater part is decomposed at about 200°, but a small quantity of ether distils unchanged. Some of this distillate was heated to 195° in current of dry air, in order to free it as far as possible from products of decomposition. The analysis of this product gave C-44.82 per cent and H=841 per cent instead of C-51.14 per cent and H=9.37 per cent.

The products analyzed appear to have been arseniate of amyl mixed with arsenic acid.

ARSENITE OF ETHYL.

The ethers of arsenious acid can be prepared more readily than these of arsenic acid, and several reactions may be employed to obtain them.

By

Arsenite of ethyl is produced in the following reactions: By the action of arsenious acid on the silicate of ethyl. the action of iodid of ethyl on the arsenite of silver. By the action of the chlorid or bromid of arsenic on the alcoholate of sodium. The iodid of arsenic and the alcoholate of sodium give no arsenite of ethyl.

When arsenious acid is heated with alcohol to about 200° in a sealed tube, a considerable quantity of the acid dissolves, and crystallizes out on cooling as beautifully formed octahedrons. A small quantity of arsenic is reduced and a corresponding quantity of aldehyd is formed. No arsenious ether is formed.

Arsenious acid was heated with a mixture of common ether and acetate of ethyl for 20 hours at 200°, but no reaction took place.

It seemed highly probable that arsenite of ethyl might be obtained by heating together, common ether and chlorid of arsenic according to the reaction

AsCl2+3(C2H)2O=(C2H5),ASO2+3С2H¿C1,

but this proved not to be the case, for after the two substances had been heated together 20 hours at 200°, it was found that no chlorid of ethyl and no arsenite of ethyl had been formed.

It has been already noticed that by a process of reduction arsenite of ethyl is produced, when arsenic acid is heated with silicic ether. When arsenious acid is heated to about 200° in a sealed tube with silicic ether, the only reaction which takes place is the replacement of the silicic acid by the arsenious acid, a gelatinous deposit of a silicic ether, containing a very large quantity of silicic acid, is formed in the tube; no alcohol, ether or gaseous body is produced, and the arsenious ether can easily be obtained pure by distillation.

Iodid of ethyl acts less readily upon the arsenite of silver than upon the arseniate of silver, and the amount of product