Mr. J. Murray on the Essays ry " Jean Rev." 93 



traces of chloride of potassium, and of sulphate of lime. Its 

 characteristics are nearly the same as those of basalts in ge- 

 neral. 



No. 37. The heat of a current of lava continues long after 

 a\\ Jiimeroles, sublimations, and efllorescences, have ceased. 



No. 38. A peculiar aromatic odour was perceived, which 

 seems to indicate the presence of some new highly volatile 

 substance. 



No. 40. The best means of guarding against the suffoca- 

 tion occasioned by the acid vapours, is to carry with one some 

 phials of solution of ammonia. 



No. 41. It may be asserted as a general fact, that hydro- 

 chloric acid is disengaged (but not exclusively), a:rLd that sul- 

 })hur becomes apparent when the temperature of the volcano 

 is below ignition, and that sulphurous acid can only be formed 

 by contact with the air and at a higher temperature. 



Some of these facts are found quoted in the Recapitiilatioii 

 des faits observes, which is given under the forty-third and last 

 number. The other facts noticed there were ah'eady more 

 or less known. 



In the memoir of Messrs. Monticelli and Covelli we must 

 notice with particular ap))robation the chemical experiments 

 with which it abounds. They are given in detail, and accord 

 with the present state of the science. This part of the study 

 of Mount Vesuvius, and of all other burning volcanos, had 

 been, until the present time, almost entirely neglected. 



XVIII. Notice on the " Essays o/Jeatsi Rey." By Mr. 

 John Murray, RL.S. M.JV.S. 

 T3ROF. BRANDE in his eloquent and able dissertation on 

 ■*■ Historical Chemistry, in the Supplement of the Encyclo- 

 paedia Britannica, has alluded to the extreme rarity of the 

 work of Jean Rey, even of the reprint of 1777. 



We are indebted to that distinguished chemist J. G. Chil- 

 dren, Est], for a masterly translation of the copy (edition 1777) 

 of these Essays (in the Library of the British Museum), and 

 published in the Quarterly Journal of the Royal Institution. 



It may not be uninteresting to mention, that I purchased at 

 Paris in February 1819 a copy of the first edition of this 

 celebrated and interesting work at the sale " de la bibliotheque 

 do M. P* * *." It was marked in the catalogue " tres rare de 

 cette edition." 



Allow me now to (juotc what I find written on the blank 

 leaf preceding tiic title page. It is scarcely possible hi perusing 



these 



