217 



mode of procuring pure carburetted hydrogen. The early product 

 of the distillation of pit-coal was washed with a solution of chlorine, 

 and afterwards with liquid potash. The residue was then mixed with 

 one fourth its volume of oxygen, and heated to 350, in contact 

 with the platinum, which converted the carbonic oxide into acid, and 

 the hydrogen into water. The carbonic acid being removed by liquid 

 potash, there remained only the carburetted hydrogen, the redun- 

 dant oxygen, and a trace of nitrogen. 



Dr. Henry concludes this communication by pointing out the best 

 method of applying the facts detailed in the preceding sections to 

 the analysis of mixtures of the combustible gases in unknown pro- 

 portions. 



A Comparison of Barometrical Measurement, with the Trigonometrical 

 Determination of a Height at Spitzbergen. By Captain Edward 

 Sabine, of the Royal Regiment of Artillery, F.R.S. Read May 6, 

 1824. {Phil. Trans. 1824, p. 290.] 



The hill selected for this comparative measurement was the highest 

 within convenient distance, of which the ascent was practicable, on the 

 western part of the north coast of Spitzbergen. The summit was less 

 than two miles from the observatory, in a direction nearly due south, 

 the observatory being upon an island rather more than a mile from 

 the main land. In consequence of the extreme inaccuracy of the 

 chart of Fair Haven, published in Captain Phipps's voyage, the author 

 has annexed to this paper a sketch of the harbour and adjacent coast, 

 to show the positions of the hill and observatory. The small bay 

 formed by the shore of the main land, to the north-east end of the 

 hill, being frozen over, afforded a perfectly level base, and correc- 

 tions for inequality were thus rendered unnecessary. A polished 

 copper cone was fixed upon a staff at the summit of the hill, the apex 

 of which was proposed as the height to be measured : it stood 44 

 inches above the highest pinnacle of the summit. Captain Sabine 

 then enters into the details of this trigonometrical measurement, 

 from which the altitude of the cone is considered as equal to 1 644 feet. 

 The author next proceeds to detail the particulars of the barometri- 

 cal measurement, and the precautions taken to insure accuracy in 

 the instruments, and in their employment ; and the height of the cone 

 thus ascertained was 1640*07 feet. 



Captain Sabine concludes this paper with some remarks upon the 

 incorrectness with which the heights of the hills on this coast are set 

 down in Captain Phipps's voyage. 



