150 Proceedings of Philosophical Societies. [Aug. 



In addition to the figures there stated, I should wish to present 

 those Gentlemen, who have turned their attention to the simple 

 and beautiful theory of spherical particles, with a cube to be 

 extracted from a tetrahedron, similar to that described in the 

 Lecture, capable of being held together by the most simple 

 power of attraction, and possessing four pair of poles, which 

 possibly may account for the phenomena discoverable in the 

 boracire. 



If from a tetrahedron consisting of seven layers a tetrahedron 

 be taken from each solid angle of three layers deep, then will 

 remain a octahedron having four spheres in each edge, and a 

 single one in the centre of each face, which is the corner of a 

 cube contained in the octahedron ; and should five spheres be 

 removed from each solid angle of the octahedron,* a cube will 

 remain, constructed exactly upon the same principle with the 

 tetrahedron and octahedron. 



The easiest way to make this cube is to take a tetrahedron 

 consisting of ten spheres, and place one sphere on the centre of 

 each face, which will produce exactly the same figure. 



Should you think the above account of sufficient importance, 

 your insertion of it in the Annals of Philosophy will greatly oblige, 

 Sir, your most obedient servant, 



N. I. Larkin, 



Article XV. 



Proceedings of Philosophical Societies. 



ROYAL SOCIETY. 



On Thursday the 1st of July a paper by Sir Humphry Davy 

 was read, containing farther observations on the new detonating 

 compound of chlorine and azote. After recovering from the 

 accident which happened to him during his original experiments 

 on this substance, Sir Humphry made a variety of experiments 

 to determine its properties and composition. Its specific gravity 

 is 1*623. When in contact with water, it congeals at about 

 40° ; but this does not happen when it is kept separate from 

 water. It detonates in nitric acid, and in ammonia; gives out 

 azote in muriatic acid, and is likewise decomposed in sulphuric 

 acid. Attempts were made to decompose it in exhausted glass 

 vessels in the state of vapour; but they were unsuccessful. In 



* The removal of the solid angles of the octahedron is only for the purpose 

 of demonstration, and is by no means intended to convey an idea that any 

 natural crystal of this shape is inclined to split in that direction, the inposSH 

 bilily of which has been abjy proved by Dr. Wollaston. 



