1813.] Eoijal Society, 71 



often as the acid is so far neutralised as to be unable to keep up 

 an adequate action. You will comprehend the intention by this 

 rough sketch — for which I beg you to pardon me, as I am un- 

 expectedly engaged, and must finish this for the packet about to 

 sail/' 



Article XI. 



Proceedings of Philosophical Societies, 



ROYAL SOCIETY. 



The Royal Society, as usual, resumed its sittings on Thurs- 

 ^lay the 5th of November. The Right Hon. Sir Joseph Banks, 

 Bart, in the cliair. A letter from Sir Humphry Davy to the 

 President was read, giving some account of a new and very 

 extraordinary detonating compound. This is tlie combination of 

 chlorine and azote, of which vve have given some account in the 

 preceding article. Our information on the subject was chiefiy 

 derived from Sir Humphry Davy's letter. We shall only add 

 here the method of preparing the compound. Expose a weak 

 solution of nitrate of ammonia to chloric gas in a jar ; tlie gas is 

 absorbed, and after a certain time a yellow oiH'-looking substance 

 is seen floating on the surface of the solution. This is the sub- 

 stance in question. Great caution is requisite in making experi- 

 ments on it. Oxalate of ammonia, and several other anmioniacal 

 salts, were tried instead of nitrate, and were found to answer the 

 purpose. 



On the 12th of November, a paper by the Astronomer Royal, 

 Mr. Pond, was read, on tlie summer solstice and the mural 

 quadrant at Greenwich. 



On the 19th, a paper on near sight, and the best remedies for 

 defective vision, by Mr. Ware, was read. There is reason to 

 believe, from the observations of Mr. Ware, that this disease is 

 much promoted by the use of glasses ; and that if glasses are 

 not employed, it soon wears off and disappears. Hence it is 

 much more common among the higher ranks than among the 

 common people. In the regiments of Life Guards Mr, Ware 

 did not find a single person afflicted with the disease, and not 

 above five or six recruits had been dismissed on account of de- 

 fective vision ; while in one of the colleges at Oxford, consisting 

 of 125 students, no less than 37 Vv'cre nearsighted. 



On the 26th, the Bakerian lecture was read by Dr. William 

 Hyde Wollaston, on the constitution of those crystalline bodies 

 whose primitive form is the octahedron or tetrahedron. It is well 

 known to crystailographers, that a kind of anomaly exists with 

 respect to these bodies, as far as regards tlieir primitive form. 

 When an octahedron is subjected to mechanical division, it is 

 separated into octahedrons and tetrahedrons. The same holds 



