1813.] Astronomical and Magnetical Observations. 227 



August 1 .—The variation is very remarkable. The morning 

 variat?on of both needles gave within 18 seconds. The noon 

 variation was less than either morning or evening. The weather 

 Mas calm, no thunder, nor any apparent cause lor so singular a 

 circumstance. At noon it was very gloomy, with the appearance 

 of a blio-ht. Greatest height of the thermometer, 68. 



Rain \ Between noon ot c the ! st ? Uly I 2-176 inches. 

 Ka n I Between noon of the 1st Aug. J 



Errata in the last Number, Article XII. 



Line 18, read b =25-07. 

 Line 18, read d = 25- 67. 



Page 139, line 3, for 1st, 2d, 3d, and 4th, read 1st, 2d, 4th, and 5th. 

 Page 139, line 12, for 1st, 2d, 3d, and 4th wires, read 1st, 2d, 4th, and 5th 

 wires: and, for Arion's belt, read Orion's belt. 



Article XI. 

 Analyses of Books. 



philosophical Transactions for 1813. Part I.] This part 

 contains the following papers ; of all of which some account has 

 been given in the first volume of the Annals of Philosophy ; but 

 we consider it as necessary to give an analysis of them here, in 

 order to correct the mistakes, and supply the deficiencies, of our 

 former accounts. 



I. On a new detonating Compound. By Sir Humphry Davy, 

 LL.D. F.R.S.] This is the substance of which an analysis by 

 Sir H. Davy is given in our seventh number, under the name 

 of axotane. We now know that the original discoverer of it was 

 a M; Dulong, and that he obtained it by passing a mixture of 

 chlorine and azotic gas through a solution of sal ammoniac. He 

 lias lately published a paper on the subject in the Annates de 

 Chimie; but it contains nothing that we did not know before. 

 Azotane has the colour and fluidity of olive oil ; its specific 

 gravity is above 1'6. It detonates with a bright light when 

 heated in water, and when brought in contact of oil or phos- 

 phorus : it acts slowly on ether and alcohol : with mercury it 

 forms corrosive sublimate : on tin and zinc it has no action : 

 neither does it act on sulphur or resin : it explodes in alcohol 

 and ether, having phosphorus in solution: in muriatic acid it 

 gives off gas rapidly, but does not explode: it has but little 

 action on sulphuric acid. Sir H. Davy conceives it probable, 

 from the propei ties and formation of this substance, that it is a 

 C i impound of chlorine and azote ; an opinion which he has since 

 verified by a direct analysis. 



v 2 



