lR.oyal Society. 387 



Fcfent Combinations of Fluoric Acid. By John Davy, Esq* 

 Communicated by Sir Humphry Davy, Knt. LL.D. Sec. 

 R.S. — 8. On a Periscopic Camera Obscura and Microscope, 

 By William Hyde Wollaston, M^D.Sec. R.S.— 9. Further 

 Experiments and Observations on the Influence of the Braia 

 on the Generation of Animal Heat. By B. C. Brodie, Esq. 

 F.R.S. Communicated to the Society for promoting the 

 Knowledge of Animal Chemistry, and by them to the Royal 

 Society,— 10. On the different Structiues and Situations of 

 the Solvent Glands in the digestive Organs of Birds, ac- 

 cording to the Nature of their Food and particular Modes 

 of Life. By Everard Home, Esq. F.R.S.— 11. On some 

 Combinations of Phosphorus and Sulphur, and on some 

 other Subjects of Chemical Inquiry. By Sir Humphry 

 Davy, Knt. Sec. R.S. -1 ' ^ ^ 3 



LXiX. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



1 Hts Society resumed its sittings on the 5th of November^ 

 the Right Hon. Sir Joseph Banks in the chair. 



A letter from Sir H. Davy to the President was read. 



In this letter Sir H. Davy describes the properties of a 

 new and very extraordinary detonating compound. 



It may be formed by exposing chlorine, or oxymuriatic 

 gas, to a weak solution of ammonia, of nitrate or of oxa- 

 late of ammonia. 



h appears in the form of a yellow oil, heavier than water. 

 It appears to be composed of chlorine and nitrogene. It 

 detonates violently by a heat below tliat of boiljng water^ 

 and even explodes by a very gentle friction. 



It seems to be by far the most powerful explosive sob- 

 stance known. Sir H. Davy, in endeavouring locoUect the 

 products from the explosion of a small panicle not bigger 

 than a grain of mustard seed, was severely wounded in the 

 f-ye, and the vessel in which the experiment was made was 

 broken into pieces. 



Sir H. Davy stated in his letter, that the first notice of 

 the exist(-nce of such a substance was contained in a letter 

 he receive d from a gentleman at Paris, but the manner of its 

 preparation was not mentioned j and though said to be dis- 

 covered a year ago, no rel'crcuce to it is made iu any of the 

 French journals. 



On the 12th was read an interesting paper by the Astro- 

 nomer Royal, Mr. Poiul, on the summer solstice and the 

 mural quadrant at Greenwich. 



On the i0th, a paper on what is called near-sight, and the 

 Bb's best 



