dissolved in an excess of hydrochloric acid, and the solution diluted with a considerable amount of water, then this same powder of algaroth is precipitated. The composition varies with the relative amount of water; namely, between the limits SbOCl and Sb_{4}O_{5}Cl_{2}. The latter compound is, as it were, a basic salt of the former, because its composition = 2(SbOCl)Sb_{2}O_{3}. With bromine and iodine, antimony forms compounds similar to those with chlorine. Antimonious bromide, SbBr_{3}, crystallises in colourless prisms, melts at 94°, and boils at 270°; antimonious iodide, SbI_{3}, forms red crystals of sp. gr. 5·0; antimony trifluoride, SbF_{3} separates from a solution of antimonious oxide in hydrofluoric acid, and SbF_{5} is formed by a similar treatment of antimonic acid. The latter gives easily-soluble double salts with the fluorides of the metals of the alkalis. De Haën (1887) obtained very stable double soluble salts, SbF_{3},KCl (100 parts of water dissolve 57 parts of salt), SbF_{3},K_{2}SO_{4}, &c., which he proposed to make use of in the arts as very easily crystallisable and soluble salts of antimony. Engel, by passing hydrochloric acid gas into a saturated solution of antimonious chloride at 0°, obtained a compound HCl,2SbCl_{3},2H_{2}O, and with the pentachloride a compound SbCl_{5},5HCl,10H_{2}O. Bismuth trichloride, BiCl_{3}, gives a similar compound. Saunders (1892) obtained 5RbCl,3SbCl_{3} and RbCl,SbCl_{3}. Ditte and Metzner (1892) showed that Sb and Bi dissolve in hydrochloric acid only owing to the participation of the oxygen of the air or of that dissolved in the acid. The heaviest analogue of nitrogen and phosphorus is _bismuth_, Bi = 208. Here, as in the other groups, the basic, metallic, properties increase with the atomic weight. Bismuth does not give any hydrogen compound and the highest oxide, Bi_{2}O_{5}, is a very feeble acid oxide. Bismuthous oxide, Bi_{2}O_{3}, is a base, and bismuth itself a perfect metal. To explain the other properties of bismuth it must further be remarked that in the eleventh series it follows mercury, thallium and lead, whose atomic weights are near to that of bismuth, and that therefore it resembles them and more especially its nearest neighbour, lead. Although PbO and PbO_{2}, represent types different from Bi_{2}O_{3} and Bi_{2}O_{5}, they resemble them in many respects, even in their external appearance, moreover the lower oxides both of Pb and Bi are basic and the higher acid, which easily evolve oxygen. But judging by the formula, Bi_{2}O_{3} is a more feeble base than PbO. They both easily give basic salts.