It is readily oxidised by nitric acid and by acid oxidising solutions, less easily by neutral or alkaline solutions. Potassium permanganateis reduced by it to manganate. It is but little acted upon by sulphur dioxide solution in absence of acids, but is slowly reduced by it to the elemental state.

Liquid sulphur trioxide appears to be without any action upon tellurium monoxide, even when boiled upon it. The monoxide becomes, indeed, slightly reddened, but remains otherwise unchanged, and when heated, does not exhibit the least intumescence, as it would do if converted into sulphoxide. The slight reddening observed may with certainty be attributed to the action of a trace of sulphuric acid, partly in the sulphur trioxide, partly formed by hygroscopicmoisture in the tellurium monoxide. Sulphuric acid is immediately and strongly coloured red by the monoxide, which dissolves completely in it, but rapidly deposits a considerable quantity of crystalline telluroussulphate

2TeO3SO,H2 = Te(O,S); + SO,Te + 30H2.

Hydrochloric acid gas is absorbed by it, but without much apparent change until a gentle heat is applied, when it partly melts to a brownish-black liquid, and then sublimes as a dark-greenish powdery solid, which is decomposed by water into hydrochloric acid, tellurous acid, and tellurium, and is therefore the already known dichloride of tellurium.

No compound of tellurium monoxide has been obtained by us, and we are unable to assign to it either acid or basic properties. Analogy would make it basic, since the dioxide can act as a feeble base. The monoxide is, however, very probably of complex constitution, more complex than the dioxide can be.

The existence of this new substance only in the solid and amorphous state, and its inability to form compounds, unless we regard the sulphoxide as one, may, perhaps, suggest to others, as such facts did at first to us, doubts of its individuality. We will, therefore, state the results of an examination we made for comparison of the properties of a mixture of free tellurium with an equal weight of tellurium oxidised to dioxide. The tellurium used was in the reguline state rubbed to fine powder. Precipitated tellurium, not easily obtained so pure, was found to be scarcely more sensitive to reagents than the monoxide obtained as above.

This mixture is whitish-grey, and remains so after it has been heated, like the monoxide, to 230° in a vacuum. It is at once resolved by a solution of potassium hydroxide into its ingredients. In cold hydrochloric acid gas it becomes wet, in consequence of formation of the liquid tetrachloride from the dioxide. When heated,

the mixture of tetrachloride and free tellurium behaves, of course, like the monoxide, in yielding the dichloride.

The behaviour of the mixture in liquid sulphur trioxide is strikingly unlike that of the monoxide. It assumes a light-pink colour, and is changed into a mixture of unaltered tellurium dioxide and tellurium sulphoxide, and when the mixture is heated, causes it to swell up enormously. It is, perhaps, necessary to mention here that tellurium dioxide and sulphur trioxide do not combine together. Lastly, in sulphuric acid, the mixture becomes mechanically separated into its ingredients, the dioxide rendering it milky, while the free tellurium is deposited, and dissolves very slowly and slightly, forming a pink colour.

XLI.-On Tellurium Sulphoxide.

By EDWARD DIVERS and M. SHIMOSÉ.

But, soon afterwards, June, and that of the

IN connection with a reaction which we had observed between sulphuric acid and tellurium compounds, we made experiments, some time ago, upon the action of sulphur trioxide upon tellurium. These resulted in the discovery of the sulphoxide of tellurium, of which, at that date, no account had then reached us. we found in the number of the Berichte for Journal of this Society for August, abstracts of Rudolph Weber's paper announcing the prior discovery of this substance. On reading these accounts, however, we noticed that our results were not quite in accordance with his, and we therefore proceeded to complete our own experiments.

The Tellurium used.-We obtained tellurium free from the mud of the lead chambers of the Imperial Japanese Sulphuric Acid Works in Osaka. The greater part of the tellurium existed in the weak acid supernatant liquor of the mud. This mud had been exposed to the air for a long time, and the tellurium had become oxidised and dissolved during the exposure. From this liquor the tellurium, mixed with a little selenium, was precipitated by hydrogen sulphide. The washed precipitate was dissolved in nitrohydrochloric acid, and the solution precipitated by sulphur dioxide. The washed precipitate was dissolved in melting potassium cyanide, and the product, after cooling, treated with water. After leaving the mixture at rest, the clear solution was decanted from insoluble matters, and precipitated by a

current of air. The precipitate was washed and dried, and distilled in a hard glass tube in a current of carefully purified hydrogen.

The Sulphur Trioxide used.-This was prepared, and rectified, and combined with the tellurium in a piece of glass apparatus, consisting of a piece of combustion-tube drawn out as shown in the figure.

The tellurium, finely powdered, and dried in a water-oven was introduced, in weighed quantity, into the seventh receptable, through the drawn-out end of the tube. The tellurium did not adhere to the sides of the tube. Dried air having been passed through the apparatus for a considerable time, both before and after the introduction of the tellurium, the drawn-out end was sealed. Through the other end a considerable charge of sulphuric acid and phosphorus pentoxide was then introduced into the first receptacle, and the funnel-like end sealed off in the lamp. Ice having been applied to the second receptacle, the mixture in the first was gently heated until enough sulphur trioxide had distilled into the second. The first receptacle was then sealed off. The sulphur trioxide was next successively distilled into the third, fourth, fifth, and sixth receptacles. Only in the second was there any sensible residue after very gentle heating. The other receptacles having been sealed off, one after the other, there remained only two in connection, one holding the sulphur trioxide, the other the tellurium. The sulphur trioxide thus prepared was a mobile liquid, crystallising in transparent prisms, and having for some time, at least, a melting point of about 15° C.

Preparation of the Tellurium Sulphoxide.-Sometimes we distilled the sulphur trioxide over into the tellurium, but we found it preferable to pour the oxide on to the metal, because in this way we could ensure contact of all the particles of the latter with the former. The two substances remain in contact for a short time without reaction, and for a longer time if the mixture is cold enough. The reaction takes place with distinct evolution of heat, and becomes visible by conversion of the loose grey tellurium into the more bulky, deep red, coherent sulphoxide. The supernatant trioxide in excess remains quite colourless, as observed by Weber. The reaction appears to be complete in a few moments after it has set in. The new solid having

been digested in the liquid oxide for some time at a temperature of 30—40°, the latter was drained off into the other receptacle and this was sealed off. The other sealed end was connected with a Sprengel pump, and its point broken off within the caoutchouc tube. The sulphur trioxide adhering to the tellurium compound was then removed, as completely as possible, by letting the mercury fall for an hour, while the tube holding the sulphoxide was immersed in water at about 35°. A long tube packed with borax and drawn out at each end, and interposed between the pump and the preparation-tube, served very effectively to arrest any sulphur trioxide. Potassium hydroxide, used at first instead of borax, was acted upon so violently as to melt and sometimes choke the tube. The preparation-tube was finally detached momentarily from the pump, so as to admit air, and its open end was then sealed.

Properties and Composition of Sulphoxide.-The sulphoxide, thus prepared, is an amorphous solid, which softens without melting at about 30°. It is of a beautiful red colour, and transparent in very thin layers. So far, it is just as Weber has described it. It is finely vesiculated, in consequence of the vaporisation within its substance of the excess of sulphur trioxide at first mixed with it. This vesicular state lightens the shade of the redness of the substance, and the walls of the vesicles are so thin as to make the surface of the mass iridescent.

Weber (loc. cit.) describes it as being very unstable, decomposing even in sealed tubes at ordinary temperatures, and yielding sulphur dioxide. But, according to our experience, it appears to be quite stable at ordinary temperatures in the closed tube when pure, neither changing colour nor evolving sulphur dioxide.† During its preparation and purification, also, no sulphur dioxide was produced, when the sulphur trioxide was quite anhydrous. The sulphoxide does, indeed, sometimes slowly decompose when left in the crude state, its red colour assuming a brown shade, and then, too, sulphur dioxide is We have not succeeded in determining the conditions of the occurrence of this change. Possibly it depends upon the sulphur trioxide used not being quite anhydrous. At one time we thought that it might be due to this action of light, but experiment has not confirmed our supposition.

And tellurium also, according to the abstract in this Journal, but if so it must yield either tellurium dioxide or sulphur trioxide as well.

A specimen of it, prepared on or about January 18th, will be laid before the meeting at which this paper is read, and it will be interesting to see whether it has remained unchanged during an interval of some months and a journey half round the world. [The specimens received from the authors, judging from their description, are unaltered.-HENRY E. ARMSTRONG.]

We have several times analysed the red sulphoxide, but only in one case have we found it to contain exactly the quantity of sulphur trioxide indicated by the formula SO,Te, all the analyses giving an excess of SO3. This one case, however, assuming the absence of error in our analysis, must be regarded as establishing its composition. The excess of sulphur trioxide in the other cases was most probably due to a retention of some of this substance within cavities in the viscid Weber assigns to the sulphoxide the composition as we indicated by the above formula, having obtained in one case the calculated quantity of tellurium, in another a very little less than this. He purified his preparations from sulphur trioxide by pressing the warm viscid masses with a glass rod. This method of purification proved impracticable in our hands.

mass.

The details of our analyses are as follows:-The weight of tellurium used was taken before converting it into the sulphoxide; one point of the sealed tube containing the purified sulphoxide having been scratched with a file, the tube was weighed, its point cracked off, and the open end immersed in a dilute solution of bromine and hydrochloric acid. Very gradually this solution was allowed to act on the sulphoxide, so as to avoid loss by violent action. The tube, having been washed out and dried was weighed; the difference between the two weighings gave the weight of the sulphoxide, and the difference between this and the weight of the tellurium, gave the weight of the sulphur trioxide; but to make certain of the absence of water or any other foreign matter, the telluric acid in solution was reduced to tellurous acid by boiling with hydrochloric acid, and the sulphuric acid precipitated by barium chloride and weighed. These were the results: