Element Antimony, Sb, Metalloid. Is allied on the one hand to bismuth, and on the other, to arsenic and phosphorus. It therefore forms a transition element between the metals and the non-metals, but is still essentially on the side of the metals. Its combining weight is Sb. Probably, therefore, we are dealing with a mixture of different kinds of vapour, perhaps Sb. Is known from high antiquity. Oriental countries were familiar with Antimony.

Element Arsenic, As, Metalloid. In accordance with its smaller combining weight, arsenic. Deviates still more than antimony from the type of the metals, and exhibits greater similarity to the non-metal phosphorus; at the same time the tendency to form acid compounds increases. In fact the resemblance of arsenic to phosphorus is so great that it might also have been treated along with that element among the non-metals. If the vapour of arsenic. At the same time, other kinds of amorphous arsenic are formed.

Element Bromine, Br, Halogene. The vapour of bromine is very heavy. If a small bulb filled with bromine be broken, or if, by means of a pipette, a drop of bromine be placed at the bottom of a large, empty bottle, it is seen that the brown-yellow vapour produced remains at the bottom and sways heavily when the bottle is moved. Only after standing undisturbed for a considerable time does the bromine.

Element Chlorine, Cl, Hallogen.

Element Iodine, I, Halogene. Is allied to chlorine and bromine, and forms a third similar element. Of the three, it has the highest combining weight, amounting to 126. 86, and its properties show deviations from those of bromine chiefly in the same direction as those of bromine deviate from chlorine. Vapour is very considerable, being about nine times as great as that of air. The molar weight is 254 and the vapour has, therefore, the formula I.

Element Phosphorus, P, Non Metal. The name phosphorescence, used in physics for the after luminescence shown by certain substances after a previous exposure to light, is a relic of that usage. At the present day, the name phosphorus. The nerve and brain substances, more especially, are comparatively rich in phosphorus, which is there .

Element Tellurium, Te, Metalloid. While iodine is very similar to bromine, if not in external appearance, at least in the nature of the corresponding compounds, the differences between selenium and tellurium are more pronounced, so that it has repeatedly been regarded as doubtful whether these two elements ought to be regarded as members of the same family. The combining weight of tellurium, Te. Combines with the metals to form tellurides; these correspond to the sulphides.