64 Royal Society. 



ever the quantity of iron they contain creates the necessity of mea- 

 sures being taken for counteracting local attraction. 



It has been alleged that the adjustments for local attraction made 

 in northern latitudes are not correct when the ship is south of the 

 equator; but the author states that, in the Pluto, he observed no dif- 

 ference ; that ship having made, while under his command, passages 

 of many thousand miles, comprising 94 degrees of latitude, namely 

 from 51° North to 43° South, and 153 degrees of longitude, namely 

 from 30° West to 123° East, during the whole of which he never 

 found any other correction for the compasses necessary excepting that 

 required for the magnetic variation, the local attraction having been 

 completely neutralized. 



A diagram is subjoined, showing the positions of the compensating 

 magnets with relation to the compass. 



" Practical Remarks on Annealing Flint-Glass. " By Apsley Pellat, 

 Esq., of the Falcon Glass Works, Holland Street. Communicated 

 by Joshua Field, Esq., F.R.S. 



This paper is entirely occupied with practical details relating to 

 the art of annealing flint-glass and depriving it of colour, the author 

 stating that he leaves the rationale of these facts to be explained by 

 philosophers. He thinks, however, that they are reconcileable with 

 the theory of Scheele, as explained by Bergman, and detailed by 

 Murray in his work on Chemistry. 



April 6. — " Determinations of the Magnetic Inclination and Force 

 in the British Provinces of Nova Scotia and New Brunswick in the 

 summer of 1847." By Professor George W. Keely, of Waterville 

 College, Maine, United States. Communicated by Lieut. -Col. Sa- 

 bine, R.A., For. Sec. R.S. 



The observations recorded in this paper are of two kinds ; first, 

 those for the relative total force, which were made with a pair of 

 Lloyd needles and an inclination- circle, seven inches in diameter, with 

 two verniers reading to single minutes ; and secondly, those for the 

 absolute horizontal force made with a unifilar magnetometer. After 

 a detailed description of these instruments, the results of the ob- 

 servations are given, occupying several pages of tables. 



May 1 1 . — " On the Chemical Nature of a Wax from China." By 

 Benjamin Collins Brodie, Esq. Communicated by Sir Benjamin Col- 

 lins Brodie, Bart., F.R.S. 



The wax which is the subject of this investigation, is a substance 

 imported into this country from China. It has the general appear- 

 ance of spermaceti, but is harder than that body. The author gives 

 reasons for believing that this wax, like bees'-wax, is a secretion from 

 an insect. 



The wax may be decomposed by fusion with hydrate of potash, by 

 which process two substances are procured; namely, a wax acid, 

 which, combined with the potash, forms a soap ; and another body 

 which is dissolved in the soap solution. By precipitation with chlo- 

 ride of barium and washing out the dried baryta salt with ether, or 

 other suitable solvents, the two substances may be separated. 



