Royal Society. 235 



the Great Plateau. It would be necessary to cut down this plateau 

 as much as 6000 feet to reduce the deflexions at A and B to 5" - 236, 

 even were the whole mass on the doubtful region non-existent; so 

 that it appears to be quite hopeless, by any admissible hypothesis 

 relative to heights, densities, &c, to reduce the calculated deflexion 

 so as to make it tally with the error brought to light by the survey. 



After entering into some elaborate calculations confirmatory of 

 the previous results, the author concludes by calculating the form of 

 the Indian arc, that is, by determining what spheroid of revolution, — 

 the axis of revolution being the earth's axis, — would most nearly 

 coincide with that arc without reference to the rest of the earth, the 

 data employed being the lengths and amplitudes of the northern and 

 southern portions of the arc, and of course their sum, and likewise 

 the latitudes, or at least approximate latitudes, of the middle points 

 of the arcs. By using the amplitudes uncorrected for mountain 

 attraction, the author obtains for the value of the ellipticity deduced 

 from the Indian arc alone ^5, nearly agreeing with J5pg, Avhich is 

 Col. Everest's result ; but by using the amplitudes corrected for 

 mountain attraction according to the author's calculation, the ellipti- 

 city is reduced to 55-3. He concludes that the arc is more curved 

 than it would be if it had the mean ellipticity of the earth, and 

 regards the supposition of a general deviation of the earth's surface 

 in that region from the mean spheroidal form as the most satisfactory 

 mode of accounting for the discrepancy. 



" On the Value of Steam in the Decomposition of neutral Fatty 

 Bodies." By George Wilson, Esq. 



In the course of a long series of experiments conducted on a large 

 scale, the author has observed that the so-called neutral fatty bodies 

 may be resolved, without danger of injurious decomposition, into 

 glycerine and fatty acids, provided the still is maintained at a uni- 

 form high temperature, and that a continuous current of steam is 

 admitted into it. 



The temperature required to effect the splitting of the fats into 

 their proximate elements varies with the nature of the body itself, 

 but all hitherto tried may be resolved into glycerine and fatty acid 

 at a temperature of 560° Fahr., many at much below that tempera- 

 ture. At a further period it is the author's intention to lay before 

 the Society a detailed account of his experiments, with the confirma- 

 tory analyses, but in the mean time he states that palm oil, cocoa- 

 nut oil, fish oil, animal tallow, Bornean vegetable tallow, " Japan 

 vegetable wax" (more properly tallow), and several others have 

 yklded satisfactory results, the fatty acid and glycerine distilling 

 over together, but no longer in combination, and separating in the 

 receiving vessel. 



Dec. 14, 1854. — The Lord Wrottcslcy, President, in the Chair. 



" On the Structure of some Limestone Nodules enclosed in Scams 

 of Bituminous Coal, with a Description of some Trigonocarpons con- 

 tained in them." By J. D. Hooker, M.D.,F.R.S., andE. Binucv, Esq. 



The authors first describe the occurrence of the limestone nodules, 

 which form a continuous bed in the centre of a thin seam of bitumi. 



