Optical investigation of solidified gases.—III. The crystalline properties of chlorine and bromine

Abstract Of the crystalline properties of the halogens only those of iodine are known. Of bromine, Arctowski has, at —78°, obtained red needles from a solution in carbon bisulphide, but these have not been further examined. Dewar, quite early in his researches at low temperatures, stated that solid bromine gets much lighter in colour when it is cooled to the temperature of liquid hydrogen. Chlorine and fluorine behave similarly; beyond this nothing is known as to the crystal properties of solid chlorine. Chlorine and bromine have, therefore, been investigated in continuation of the work described in 'Proc. Roy. Soc.,' A, vol. 87, p. 371, and A, vol. 88, p. 61. Chlorine. In order to obtain pure chlorine the gas was prepared from gold chloride and generated in the same piece of apparatus as was subsequently used for crystallising it. The device is shown in the figure.