Mr. W. Crookes discovered the new metal thallium by means of its spectrum, which differs from every other in having one bright green line upon a dark ground. He obtained its various salts, and the metal itself, which he describes as being heavy, dense, and very like lead, but of greater specific gravity. Its fresh surface has a bright metallic lustre, not so blue as that of lead, but it tarnishes more easily. It is so soft that it can be indented by the nail, yet it can be drawn into wire, and in chemical properties it resembles mercury, lead, and bismuth. Altogether it is more like a metal than a metalloid, perhaps something between the two. Thallium is completely volatilized at a temperature below red heat, whether single or in composition. If the quantity be small, the green line appears in a sudden flash, lasting but the fraction of a second. If a larger quantity of the metal be gradually put into the flame, it lasts a little longer, appearing as a single green line of extraordinary purity and intensity, sharply defined on a black ground. With respect to volatility, thallium is analogous to the non-metallic element selenium, which is so volatile that its beautiful blue light only lasts a few seconds. The green light of thallium comes out more rapidly, and with less of the substance, than the blue light of selenium, a quantitative distinction which accords with Dr. Miller’s observation that the rapidity with which a result is obtained, and the minuteness of the quantity required for the examination, gives this method a superiority over every other for the qualitative analysis of the alkalies and alkaline earths. Thallium has been detected in mineral waters, wine, treacle, tobacco, and chicory. Drs. Reich and Richter discovered a fourth new metal in the zinc-blende at Freiberg in Saxony, which has been called indium, from two beautiful indigo-blue lines in its spectrum, which have a greater refrangibility than the blue lines in strontium. The chemical relations of indium resemble those of zinc, with which it is associated in nature. The metal can be reduced before the blowpipe into a bead, which marks paper and has the colour of tin.