372 Prof. Partington and Mr. Cant on the Specific Heats 



sticks of caustic soda, in the case of ammonia ; in the case 

 of sulphur dioxide and carbon dioxide both contained 

 phosphorus pentoxide. There was dry glass wool at M, 

 and contained pumice soaked in sulphuric acid in the case 

 of ammonia, otherwise soda-lime. P was intended to collect 

 any liquid passing over from 0. 



The liquid in B was kept in the freezing mixture, and most 

 of the air in the apparatus removed by the pump. At the 

 temperature used, the liquid ammonia or sulphur dioxide 

 had no appreciable vapour-pressure. The tap connecting 

 H and Gr was turned off and the vessel A removed. Ammonia 

 or sulphur-dioxide gas from B gradually rilled the whole 

 apparatus to atmospheric pressure, as indicated by the 

 mercury manometer F. The vessel A was then restored to 

 the freezing mixture, and the process of exhaustion and filling 

 repeated four times. In this all the air in the apparatus 

 above the tap on H was removed. The tap S was then 

 turned off, B immersed in the freezing mixture, and the 

 apparatus exhausted to the highest degree possible. The tap 

 above H was turned off and, by removing the freezing 

 mixture and turning on tap S, the tube L was allowed to fill 

 with gas to atmospheric pressure. This process was repeated 

 six times, and by this time the tube contained very pure gas 

 obtained by the fractionation of the liquid in B. The pressure 

 was then adjusted to 76 cm. and the gas tube sealed off at 

 K 2 , about 4 in. from the end of the wider tube. The 

 portion KiK 2 was then sealed off, leaving only a very short 

 length on the tube L. The parts K x and K 2 had previously 

 been thickened and drawn out for convenience in sealing 

 off. The portion of tubing KjE^ was then carefully opened 

 under water, in the case of ammonia and sulphur dioxide, or 

 potash in the case of carbon dioxide. In all cases the liquid 

 filled the tube completely without leaving the slightest 

 bubble of air. 



The gas tube was then held in a horizontal position by 

 gripping it in the middle with a clamp (fig. 2). This clamp 

 consisted of two rectangular blocks of wood, each having a 

 semicircular recess cut in it and lined with felt. The two 

 blocks were hinged, and at the opposite side fitted with a 

 large screw passing freely through the upper block and 

 engaging in a thread in the lower block. This clamp was 

 fixed firmly to a long plank screwed to the bench. The gas 

 tube, gripped by the clamp, was supported in a horizontal 

 position by two prisms of cork placed between the tube and 

 the board. These prisms were placed at the nodes near the 

 ends, when the latter had been found by trial, and did not 

 interfere with the vibration of the tube. The tube was 



