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Messrs. J. B. Hannay and J. Hogarth. [Feb. 26, 



calcium and the end sealed. A small piece of solid paraffin was then 

 dropped into the capillary tube so that it lay next the drawn out 

 portion. When all air was expelled by heating slightly, a few frag- 

 ments of sodium were placed in the tube and the whole sealed. The 

 arrangement is shown in the Plate, fig. 3. The end containing the 

 sodium being placed in a freezing mixture, the wide tube was care- 

 fully heated until sufficient ammonia was distilled over. When re- 

 absorption commenced the fragment of paraffin was melted by the 

 application of a very small flame, and capillary attraction caused 

 it to run into the fine bore, where it solidified and prevented any 

 passage of ammonia. The tube now containing a solution of sodium 

 in ammonia, was next cut off near the join and the end sealed 

 in the blowpipe flame, the paraffin plug preventing outward pressure. 

 On heating the tube thus prepared in the air bath, the blue colour 

 disappeared before the critical point was reached, and the loss of 

 colour was accompanied by the deposit of a white powder. It was 

 at first thought that this was due to the presence of water in the 

 ammonia, but many experiments, in which every care was taken to 

 have the ammonia perfectly dry, failed to give any other result. In 

 one case only, when the temperature had been raised very rapidly, did 

 the blue colour remain above the critical point, and this only for a few 

 seconds. This chemical action most probably consists in the formation 

 of sodamide, and this view is supported by the fact that one of the 

 tubes opened under mercury gave a quantity of gas not dissolved by 

 water. 



As the solution of an alkali metal seemed best adapted for spectro- 

 scopic examination, we made an attempt to dissolve sodium in com- 

 pressed hydrogen. For this purpose a tube with a very large expan- 

 sion was made, and filled with carefully dried hydrogen. While the 

 stream of gas was still passing, a small piece of sodium was placed 

 in a pocket at the end of the tube, and the aperture closed before the 

 blowpipe. In this experiment we used no manometer, our intention 

 being to increase the pressure slowly and to make it as great as 

 possible. After about half an hour, at a pressure so far as we could 

 judge of about 300 atmospheres, the mercury, which had never come 

 in contact with the solid sodium, was observed to become thick and 

 pasty. At this point the tube burst (no further pressure had been 

 put on) close to the iron cap, and on examining the broken piece small 

 semi- solid globules of mercury were observed adhering to the glass, 

 marking the highest point to which the mercury had reached. These 

 were taken out and placed in water, when small bubbles of gas were 

 observed rising from them. In another experiment a small rod of 

 sodium, quite filling the capillary bore, was observed to be gradually 

 corroded, until only a shell adhering to the glass remained. The very 

 frequent bursting of the tubes, made more frail by the reduction of 



