2 



Prof. T. S. Humpidge. 



to 300° made byNilson and Petterson* confirmed this prediction to a 

 certain extent, but as this important question could not be considered 

 as definitely decided, the following investigations were undertaken. 

 Owing to the small amount of time at my disposal the experiments 

 have absorbed the greater part of my leisure for the past fourteen 

 months, and in the mean time my results have been partly forestalled 

 by other investigators, but the importance of the subject justifies me 

 in publishing what is little more than a confirmation of the work of 

 others. 



My experiments may be divided into two groups, (i) those on the 

 specific heat of pure glucinum at varying temperatures, and (ii) those 

 on the vapour-density of volatile glucinum compounds. f 



I. Specific Seat of Metallic Glucinum at varying Temperatures. 



For the determinations of the specific heat of glucinum at varying 

 temperatures a fresh quantity of the metal was prepared from the 

 pure chloride by the method which I have previously described 

 (loc. cit.). The chloride was obtained from oxide which had been 

 carefully purified with ammonium carbonate. Experiments in which 

 impure glucina was fused with acid potassium fluoride, and the fused 

 mass extracted with water containing hydrofluoric acid, proved that if 

 iron is present much of it goes into solution with the glucinum. The 

 usual method with ammonium carbonate gives better results, especi- 

 ally if the process is several times repeated, and if at last an insufficient 

 quantity of the solvent is used, so that some of the glucina remains 

 undissolved with the last traces of the alumina. The concentrated 

 solution of the double carbonate £ can then be easily decomposed by 

 leading steam into it through a wide tube. The dangerous bumping 

 which always happens when the concentrated solution is boiled is thus 

 completely avoided. In this way, after three or four purifications, it 

 is easy to obtain a sample of glucina which when fused with acid 

 potassium fluoride dissolves in water containing hydrofluoric acid 

 without leaving the slightest trace. A very convenient form of 

 charcoal for mixing with the oxide to prepare the chloride is a kind of 

 lamp-black known in trade as gas-black. When burnt it leaves a 

 much smaller quantity of ash than the best sugar charcoal, and can be 

 mixed with the oxide much more easily and intimately than the latter. 



Most of the metallic glucinum prepared from this pure chloride was 

 in the form of thin, lustrous, highly crystalline lamina3. The purer 

 portions were selected and compressed in a steel mortar to a compact, 

 lustrous cylinder 11 mm. long and 8 mm. in diameter. 



* " Berlin Ber.," xiii, 1456. 



T The latter experiments were done before the former. 

 % See Appendix A. 



