411 LXIII.-CrystalEiize Molecular Compounds of Naphthalene and Benzene with Antimony Trich lo ride. By WATSON SM~TR and G. W. DAVIS. IT was observed by one of us some time ago (this Journal June 1879) that on melting a mixture of antimony trichloride and naphthalene, after removing the source of heat a beautiful crystallisation com-mences in the still liquid mass the minute but perfectly symmetrical clinorhombic tables in their rapid growth performing during the pro-cess singular gyrations upon the liquid surface on which they float. Although these crystals are formed with great facility it is no easy matter to separate them perfectly from the melted mixture in which they float owing t o the rapidity with which on removal of the crys-tals the adhering fluid solidifies upon them.This must be rapidly performed with a small platinum spatula previously warmed. It was found best to adopt the proportions by weight of 3 parts of antimony trichloride t o 2 of naphthalene. The crystals on removal froni the melted fluid in which they float must be at once placed in a dry stoppered bottle as they are very deliquescent. Immediately on removal they are observed to be transparent but a few moments later become whitish and opaque. They form perfect clinorhombic tables, and on analysis gave the following numbers :-0.5425 gram gave 0.293 gram Sb& = 0.2093 Sb = 38.58 per cent. 0.4990 , 0.269 , SbzS3 = 0.1914 Sb = 38-56 ,, Calculated for Found Sb 38-94 (i) 38.58 (ii) 38.56 3SbC1,,2CloH8 per cent. per cent. Molecular Compound of Benzene with Antimony Trichloride.Crystallised antimony trichloride is dissolved in benzene so as to give a concentrated solution. It is besi to take about 3 parts of the former to 4 of the latter. Solution may be promoted by gentle warming in a small flask which is afterwards loosely corked and then set aside for a few days. Large well-defined clinorhombic plates, much thinner and also more irregular than the naphthalene compound, are formed. They are perfectly colourless and transparent and per-manently so thus differing from the naphthalene compound. They me also exceedingly deliquescent. Analytical numbers as follows were obtained :-V O L XLJ. 2 f 412 SMITH AND DAVIS ON THE Weight taken = 0.594 gram. Antimony trisnlphide obtained = 0.3615 gram = 0.2582 gram Sb. A chlorine determination gave . . . . . . . . . . . = 43-46 per cent. 37.62 ,, Calculated for Found 3SbC1,,2C6H6 per cent. per cent. Sb = 43.57 43.46 C1 = 37.90 37.6