such an increase in the atomic weights. Having compared a great variety of spectra with that of beryllium, I am justified in making the following remarks:

The spectrum of beryllium exhibits no marked analogy with the calcium, the magnesium, or the aluminium spectra, all of which are members of well-defined homologous series. There is nothing similar to the boron, the silicon, or carbon spectra, nor to those of scandium, yttrium, or cerium. The spectrum of lithium is the one most allied to that of beryllium in the number, relative position, and intensity of the lines. The character of the lines of greatest intensity in the beryllium spectrum is more like that of the pairs of lines in the spectrum of calcium with wave-lengths 3933-3967·5 and 3705.5-3736.5. In fact the similarity to the line 3705.5 is so great that the two when juxtaposed on one plate may be mistaken if their positions be not taken into account. Lines of similar elements have very distinctive features. Individual lines of the calcium, strontium, and barium group are quite different from those of the magnesium, zinc, cadmium series, and they could not be mistaken. The lines of cerium and didymium again are quite dissimilar in character; instead of being broad they are exceedingly fine.

I am therefore led to the conclusion that beryllium is the first member of a dyad series of elements, of which in all probability calcium, strontium, and barium are homologues.

XL.-On a New Oxide of Tellurium.

By EDWARD DIVERS, M.D., Principal, and M. SHIMOSÉ, Student of the Imperial Japanese College of Engineering.

By heating in a vacuum the compound of sulphur trioxide and tellurium until it decomposes, we have obtained sulphur dioxide and a new oxide of tellurium. This oxide is in the solid state, and if sufficiently heated, suffers decomposition into tellurium dioxide and elemental tellurium, the latter volatilising before the former. Decomposition of the sulphoxide begins-according to our observations, which differ from R. Weber's-at about 180° C., but is not quite complete even at about 230°, above which temperature we have feared to pass, lest we might cause some of the new oxide to decompose.

The operation was carried on in a tube-retort, paraffin-bath, and connected with a Sprengel pump.

immersed in a

In this vessel

the required sulphoxide had itself been prepared and purified, ready for the experiment, and out of contact with the air.

The solid sulphoxide softens by the heat to a pasty mass before decomposition sets in, and when this happens, intumesces very much in giving off the resulting sulphur dioxide. At the same time its own lustrous brown colour gives place to the black colour, also lustrous, of the new oxide. The oxide now exhibits a marked resemblance to charred cork.

It is not yet quite pure. Even prolonged heating in a vacuum failed to yield it altogether free from a sulphur-compound, which can hardly be other than unchanged sulphoxide of tellurium. We have, there

fore, with the view of purifying it, rubbed the vesicular mass to powder, and washed it with water holding in solution a small quantity of sodium carbonate. This treatment effectually removes oxide (or oxides) of sulphur, together with any tellurous acid that may have resulted from the decomposition of the sulphoxide, this acid being readily soluble in sodium carbonate. Washing with hot water to remove soda, and with alcohol to remove water, and then rapid drying in the water-oven, complete the preparation of the new compound.

As thus prepared, however, it may still contain free tellurium resulting from the action of water on the sulphoxide, insignificant indeed in quantity if the heating in the vacuum has been strong and protracted, or perhaps entirely absent. For, as we shall describe. further on, the new oxide appears to be one of the products of the decomposition of the sulphoxide by water, and is undoubtedly the first tellurium-product of the reaction, the free tellurium being only a secondary product. The sulphoxide being here present in very small quantity only, and spread through a mass of the new oxide, is probably in the condition most favourable to the permanence of the products of its primary decomposition. Be this, however, as it may, experience and practice have enabled us so to improve our working as at last to prepare the oxide unmixed with any quantity of free tellurium sufficient to betray its presence on analysis, whereas at an earlier stage of our work, we obtained evidence of the presence of small quantities of tellurium diminishing in successive preparations.

The new oxide seems also to be obtained in small quantity by the action of water on the sulphoxide. This action, as Weber has pointed out, results in the production of tellurium, tellurous oxide, and sulphurous acid. But besides these substances, there are also formed sulphuric acid and, apparently, the oxide of tellurium here described. For we find the black matter precipitated by this action, not only to * Abstracts in this Journal, 42, 804, and in the Berichte, 15, 1336, of the paper in J. pr. Chem., 24, 218.

differ somewhat in aspect from tellurium reduced by sulphurous acid, in being brownish rather than bluish-black, but also to yield some tellurium dichloride when acted upon by dry hydrochloric acid. The greater part of the precipitate is undoubtedly free tellurium, and this part remains unaffected by the hydrochloric acid. If the oxide here present were the dioxide, it too would, in contact with the free tellurium, give the dichloride with hydrochloric acid, the tetrachloride being an intermediate product. But the fact of the previous washing with sodium carbonate should preclude the supposition of its presence.

The well-known purple-red solution of tellurium in sulphuric acid, when poured gradually into a very large volume of water, also yields the new oxide, apparently together with the other products obtained from the sulphoxide. But tellurium dichloride, decomposed by water, gives no monoxide even where the water used contains alkali, the sole products being hydrochloric acid, tellurous acid, and free tellurium.

The new oxide of tellurium is quite stable in dry air at common temperatures. It is black in colour with a slight brown shade, and shows, when pressed with a hard body, a graphitic lustre quite distinct from that of powdered tellurium itself, which, when the tellurium is pressed, is light-grey and much brighter.

Its composition may be expressed by the name and formula Tellurium monoxide, TeO, but its constitution is probably more complex than such a name and formula indicate. Its composition has been ascertained by oxidising it with bromine in hydrochloric acid water, precipitating the tellurium with sulphurous acid, washing the precipitate on a tared filter, and weighing. Using 0.3179 gram of one preparation, and 0.3378 gram of another, we obtained quantities of tellurium corresponding to 900 and 888 per cent. respectively. Taking Te as 128 and calculating for TeO, the tellurium comes out 88.9 per cent.

Heated strongly in a vacuum, tellurium monoxide decomposes, as already stated, into tellurium dioxide and tellurium. Heated in the air, it slowly oxidises to dioxide. In the moist state, it slowly cakes together, apparently by formation of dioxide; but whether by oxidation, or by a decomposition with water in which tellurium is liberated, or in both these ways, we have not yet determined.

Potassium hydroxide in cold solution acts but slightly upon it; but when boiled with it gradually decomposes it, leaving elemental tellurium undissolved. It is much more unstable in presence of acids. Even cold dilute solutions of hydrochloric or sulphuric acid act markedly upon it, while hot fuming hydrochloric acid at once decomposes it into tellurium and its dioxide, the latter, of course, dissolving.