Patent GB-684042-A (GB)
Title: Improvements in or relating to methods of and apparatus for measuring the saturation temperature of solutions
IPC: G01N25/14
Filed: 1950-05-22
Abstract: 684,042. Measuring temperature of saturation of a solution. GENERAL ELECTRIC CO., Ltd., and STILL, J. E. May 22, 1951 [May 22, 1950], No. 12790/50. Classes 97 (i) and 97 (iii). The temperature of saturation of a solution having a single solute, e.g. ethylene diamine tartrate crystals, is measured by observing the temperature at which a linear slit source of light appears as a straight line passing through a crystal or part of a crystal of the solute material when arranged in a volume of the solution so that the plane containing the growing face of the crystal or part of a crystal is perpendicular to the plane containing the linear light source on observing this latter from the opposite side of the crystal. The solution is continuously circulated through a circuit from a body of the solution from A by a pump 5, Fig. 1, through tubing 37 to the feed pipe 8 of a container 1 through the container to the outlet pipe 9 and tubing 11 back to the body of solution at B. This circuit includes heating means, such as the electrical resistance heating coil 38 around a glass tube 37 for controlling the temperature of the solution passing through to the container 1 which is so arranged that the solution, in passing from the inlet 8 to the outlet 9, fills completely the part of the volume thereof lying between two opposite areas of the walls which areas are transparent and plane parallel. The crystal is mounted on a wire clip stand in this volume of solution with a growing face lying in a plane intersecting both these opposite areas. A linear slit source of light 42 is mounted with the slit 42 adjustable by handle 43 in a plane perpendicular to that of the growing face of the crystal so that it may be viewed through the opposite areas and the solution passing between them. The temperature of the solution is observed on a thermometer 12 and is adjusted by regulating the current through the heating resistance 38. In the case of a solution having a positive solubility temperature coefficient at too low a temperature of the solution, e.g. 2‹ C. below saturation temperature, the observed linear source 62 appears to bend downwards as in Fig. 4c and appears to run along the growing face 61 of the crystal 60. When the temperature of the solution is too high, the linear source appears to bend upwards as in Fig. 4b and when at the saturation temperature the linear light source 62 appears to enter the growing face 61 without deviating. In the case of a solution having a negative solubility/ temperature coefficient, at too high a temperature of the solution, the linear source would appear to bend downwards, and at too low a temperature the linear source would appear to bend upwards as in Figs. 4c and 4b respectively. The liquid container 1, Fig. 1, comprises an inner container 2 surrounded by a jacket 3, both of which are constructed mainly of transparent material such as methyl methacrylate, the connection from the jacket to the inner container 2 being by channels passing through the walls of the container from the top to the bottom thereof. Specification 707,976, [Group XXXV], is referred to.