Dilatation and compressibility of liquid carbonic acid

• Published in: Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 1920
• Subjects: Buttons; Carbonic acid
• Online Access: http://dx.doi.org/10.1098/rspa.1920.0061; https://royalsocietypublishing.org/doi/pdf/10.1098/rspa.1920.0061

In a former paper it was pointed out that, in order to determine a starting point for drawing the θ Φ , and І Φ diagrams for CO 2 , it was necessary to know the coefficient of expansion of the liquid at constant pressure. The results of a series of measurements on the dilatation and elasticity of the liquid were given (fig. 11, p. 78), but it was pointed out that the results obtained were not in agreement amongst themselves, though sufficiently accurate for the purpose for which they were needed, and it was stated that a new series of measurements were about to be made. These measurements, delayed by the war, have now been completed and are described in the following paper. The dilatometer used is shown in fig. 1. It consists of a glass burette, to contain the portion of liquid carbonic acid under examination, enclosed in a steel tube capable of withstanding the necessary pressures. The lower end of the burette dips into mercury, which separates the contents from the rest of the liquid which fills the tube. Bound the bulb of the burette a coil of fine platinum wire is wound, which serves as the “bulb” of a platinum thermometer and gives the temperature of the liquid. Inside the burette a long loop of platinum wire is stretched from the top to the bottom; the lower end of this loop is short-circuited by the mercury, so that, by measuring the resistance of the remainder, the height of the mercury in the burette (which cannot be seen inside the steel tube) may be found, and hence the volume of the charge. The connections to these two platinum wires and two additional compensating leads are carried through the vulcanite plug in the top of the steel tube and sealed gas-tight in it by means of small rubber tubes surrounding little brass buttons on the wires, which are drawn tightly into conical holes in the vulcanite. The ends of the steel tube are closed by heavy brass hexagon caps, screwed on, which make gas-tight joints on thin vulcanite washers. The vulcanite plug is supported by a steel washer. The resistances of ...