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XVlI. Analysis of a JVor/c, entitled " Observations and Expert- 

 ments made at Vesuvius during Port of the Years 1821 and 

 1822: bi/ T. MoNTicELLi and N. Covelli." % M. Me- 

 nard DE LA GrOYE*. 



T^HE authors of this pamphlet, although both of them 

 -■■ Italians, have thought it advisable to write in French, 

 doubtless in order to give it greater publicitj\ Its form, and a 

 great many of the expressions which we remark in it, are in- 

 deed from a paper on the same subject published in the year 

 1815, borrowed by M. Menard de la Groye, and inserted in 

 the Journal de P/iT/siquef. It is divided into five sections or 

 paragraphs, entitled as follows : 



1°. State of Vesuvius from the time of the eruption in 

 1820 and 1821 up to February 1822; observations and ex- 

 periments made during that interval of time. 



2". Phaenomena of Vesuvius during the months of February 

 and March 1822; and observations and experiments made 

 during that period of time. 



3°. Ascent to the crater on the 16th of March. 



4°. Mineralogical and chemical examination of the products 

 of the eruption. 



5°. Last ascent to the crater on the 11th of May 1822. 



These different paragraphs, composed of descriptions of 

 forms which are known to be perpetually varying; of observa- 

 tions on phfenomena equally subject to an infinity of changes, 

 and of experiments which demand great details, in order to ar- 

 rive at a small number of results, are, hke most of the numerous 

 papers to which Mount Vesuvius from time to time gives occa- 

 sion, scarcely susceptible of a simple, clear and concise analysis. 

 V^e shall therefore confine ourselves to the task of pointing 

 out the more remarkable and certain results — those, in fact, 

 which may be regarded as steps made in the study of that 

 volcano which exhibits the most instructive and the most com- 

 plicated phajnomena of any with which we are acquainted. 

 Forty-three articles, distinguished by the same number of 

 figures, form the last division of the work. In quoting the ob- 

 servations, we shall follow the order of these numbers. 



Nos. 4. and 36. The substances emitted by the volcano {Ics 

 dejections), which cool quickly after their fall or overflow remain 

 in a state of incoherence ; but they become aggregated or ag- 

 glutinated without cement wherever they are ehher heated 



* From the Bulletin des Annonces'Scwntifiqiies, torn. ii. p. 435. 



t Observations and Reflections upon the State and Phenomena of 

 Vesuvius during Part of the Years 1813 and 1814, &c. Paris. V Cour- 

 cier, ISib. In 4to. 102 pages, with the table of contents. 



again 



