. Carnegie Institution of Washington publication. FREEZING-POINT APPARATUS. the ring was such that when wrapped with the smaller wire, it would just touch the walls of the freezing-tube, and thus hinder the formation of an ice- sheath. This device was found to give perfect satisfaction, and to be in every sense superior to the ordinary glass stirrer. The platinum stirrer was attached to a glass rod, which passed closely through a glass tube in the cork of the freezing-tube. In this way the movement of the stirrer was guided, and cramping prevented. The freezing-tube consisted of a large test-t
. Carnegie Institution of Washington publication. FREEZING-POINT APPARATUS. the ring was such that when wrapped with the smaller wire, it would just touch the walls of the freezing-tube, and thus hinder the formation of an ice- sheath. This device was found to give perfect satisfaction, and to be in every sense superior to the ordinary glass stirrer. The platinum stirrer was attached to a glass rod, which passed closely through a glass tube in the cork of the freezing-tube. In this way the movement of the stirrer was guided, and cramping prevented. The freezing-tube consisted of a large test-tube of 80 cc. capacity, sur- rounded by a second glass tube, giving an air space between the two of about a centimeter. This outer tube was surrounded by the freezing mixture, which was contained in a large bat- tery-jar wrapped with felt to diminish radiation. The freezing mixture was varied to suit the conditions, the solu- tions of lower concentrations freezing with a mixture of salt and ice, while those of greater concentrations often required the use of crystallized calcium chloride and ice. By means of a small electric ham- mer, uniform and gentle blows were delivered on the top of the thermome- ter during the time of an observation, thus overcoming the friction of the mercury in the capillary. To facilitate the reading of the thermometer, a small lens magnifying several diameters was employed, and. FIG. 1. more intense illumination of the thermometer scale was obtained by means of a small incandescent lamp. A thermometer graduated to tenths served to indicate the temperature of the freezing mixture, the effort being made to keep this only a few degrees lower than the freezing temperature of the solution under observation. CONDUCTIVITY APPARATUS. The conductivity measurements were made by the well-known Kohl- rausch method, using the Wheatstone bridge, inductorium, and telephone. Two types of cells were used. For the more dilute solutions the ordinary. Please note that th
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