446 Prof. Phillips on Subterranean Temperature, 



These experiments have not as yet been performed with 

 minute attention as to the proportions of the acting bodies, 

 although such investigation is contemplated ; but it is con- 

 cluded, that the chlorine of the chloride of sodium obtains 

 hydrogen from the water of the oxalic acid to evolve muriatic 

 acid gas, and that the sodium, obtaining its oxygen from the 

 oxygen of the water, forms soda, which combines with the 

 oxalic acid, forming oxalate of soda, decomposable at a red 

 heat into carbonate of soda. 



The chloride of calcium also undergoes decomposition 

 when heated with oxalic acid, evolving muriatic acid gas, and 

 forming oxalate of lime, which upon the further continuance 

 of the heat leaves lime. 



These researches will be extended to the other chlorides, 

 with the view of getting new results ; in the mean time it is 

 hoped that the facts now stated possess some claim to ori- 

 ginality. 



LXIV. On Subterranean Temperature, as observed at a Depth 

 of Five Hundred Yards below the Level of the Sea, in La- 

 titude 54° 55' North, November 15, 1834. By John 

 Phillips, F.R.S., F.G.S., Professor of Geology in King's 

 College, London.* 



1. r T 1 HOUGH, upon a review of the facts and reasonings 

 ■*■ concerning the interior temperature of the globe, we 

 may freely admit that below a certain depth from the surface 

 the thermometric heat becomes continually greater as we de- 

 scend, so many sources of embarrassment occur in the prose- 

 cution of experiments, that it is by no means an unreasonable 

 scepticism to doubt, whether the law of the augmentation of 

 heat in proportion to the depth is even approximately known. 

 Those who, from local and practical experience, are the best 

 enabled to judge of the corrections required for the effects of 

 respiration, light, friction, and chemical action, on the one 

 hand, and of the ventilating air on the other, must allow that 

 the interference of these causes of error, though less consider- 

 able than is sometimes imagined, is of serious consequence 

 in so delicate an inquiry. 



2. Immediately after leaving Edinburgh, in October, I was 

 at Newcastle for a week, and was informed by Mr. Hutton, of 



* Communicated by the Author: in the Phil. Mag. first series, for 1823, 

 vol. Ixi. p. 347, 436, and vol. Ixii. p. 38, 94, will be found a review, drawn 

 up by Mr. Brayley, Jun., of the experiments on Subterranean Temperature 

 which had then recently been made in the Mines of Cornwall and the North 

 of England, exhibited in a tabular form. See also vol. Ixvii. p. 302, and Phil. 

 Mag. and Annals, N.S. vol. ix. p. 94. 



