50 Mr. F. Baily on the ensuing 



jects of consideration in the article on liquid substances. 

 Water is an important agent, mechanically and chemically, 

 among those of a volatile nature. Among the gaseous sub- 

 stances, muriatic acid is evolved at all periods of the eruption, 

 and at all temperatures. 



Art. IV. Of the Currents of incoherent Lava. 



Art. V. Of the Currents of Ashes. 



Art. VI. Of the Aggregates formed by those Substances. 



Art. VII. Of the Mofette produced by the Carbonic Acid. 



Art. VIII. Of Obsidian, a rare Species of Lava at Ve- 

 suvius. 



In Art. IX. is given A Catalogue of the Products of the 

 Eruption of October 1822 : In Art. X. the Details of the che- 

 mical Processes, which they followed in their Analytical Exa- 

 mination of the Substances produced in this last Eruption. 



Art. XII. contains two tables of Meteorological Observa- 

 tions made during the months of October and November 1822, 

 at the Observatory of Naples, at the distance of about eight 

 miles from Vesuvius. It also contains a recapitulation of the 

 most remarkable facts observed in the course of the last erup- 

 tion, and since that period. 



The figures represent, 1st, Vesuvius viewed from the road 

 of the Hermitage a few days before the eruption of October 

 1822; 2d, this eruption observed from the same situation at 

 eight in the evening; 3d, the Volcano seen from Bosco-tre- 

 Case ; 4th, a drawing of the Crater made upon the spot, on 

 the 16th of November 1822. 



XI. On the ensuing Opposition of Mars. By F. Baily, Esq. 

 F.R.S. Read before the Astronomical Society of London, 

 January 9, 1824-.* 



\ T a time when we have two new and excellent observa- 

 ^*- tories established in the southern hemisphere, where 

 the celestial phtenomena are watched and observed with the 

 greatest diligence and zeal, it becomes the more important 

 and necessary that corresponding observations of a certain 

 class of those phaanomena, of not very frequent occurrence, 

 should also be made in the northern hemisphere, by such 

 persons as are fortunately possessed of the requisite means 

 for this purpose. Without this co-operation, the labours of 

 those industrious observers will lose much of their value, and 

 the advantageous opportunity of elucidating an important 



* See our report of the proceedings of the Society at page 61. 



branch 



