Chemistry. 365 



Sir D. Brewster read a notice of very powerful magnets 

 made by the process of M. Elias, and, under his direction, by 

 M. Logemon, optician, Haerlem. By this process a magnet 

 1 lb. weight will, with due precaution, support 28^ lbs., and 

 the power does not sensibly diminish though the armature 

 be suddenly detached several times. It has twice the power 

 of magnets commonly made in Britain. Magnets capable 

 of raising 400 lbs. are made in this way. Sir David ex- 

 hibited two of M. Elias's magnetic horse-shoe combinations 

 of bars, one of about 17 oz. weight, and another 12^ lbs., 

 the latter capable of supporting 150 lbs. It was necessary, 

 for their perfect action, to polish the ends of the armature 

 with two pieces of wood covered with emery and lead. The 

 line joining the poles must be as perfectly horizontal as pos- 

 sible. The bars are magnetized by being moved several 

 times through a helix of copper wire, along which the galvanic 

 current passes. 



Short communications were made by Sir D. Brewster, on 

 the Optical properties of Cyanuret of Magnesia and Platina ; 

 on a New Membrane investing the Crystalline Lens ; and 

 on some phenomena of the Polarisation of the Atmosphere. 

 By Professor Stevelly — On an attempt to explain the occa- 

 sional distinct vision of revolving coloured sectors. By Pro- 

 fessor Stokes — On the mode of disappearance of Newton's 

 Rings in passing the angle of total internal reflection. By 

 Professor Hennessy — On the distribution of Shooting Stars 

 in the Interplanetary spaces. By Mr J. A. Broun — On Elec- 

 trical Figures of Dust on Plate Glass ; and by Mr Beswick, 

 in Explanation of a Magnetic Chart on which the lines had 

 been drawn by a theoretical formula. 



Section B. — Chemistry, including its Applications to 

 Agriculture and the Arts. 



" On the action of the Soap Test upon Water containing 

 a salt of magnesia only, and likewise upon water containing 

 a salt of magnesia and a salt of lime," by Mr D. Campbell.* 



" Remarks on some Chemical Facts connected with the 



* This papor published in the 37th Vol., p. 171, of the Philoeophical Maga- 

 zine for 1850. 



