48 MM. Monticelli and Covelli on the late 



existed before the horrible catastrophe of the year 79. The first 

 section is entitled " The State of Vesuvius from the Eruption 

 of 1820 and 1821 to the Commencement of October 1822; 

 with Observations and Experiments." It contains an article 

 on the state of the volcano from the 11th of May 1822 to the 

 beginning of October, not inserted in the work which pre- 

 ceded it; from which it also differs in some other respects 

 towards the end. The second section is a " Journal of the 

 Eruption of October 1822." The authors first speak of the 

 state of the atmosphere during the spring, summer, and 

 autumn which preceded that eruption; a state rendered more 

 remarkable by the excessive drought which prevailed. They 

 mention some movements of the volcano precursory to the 

 eruption ; and then proceed to the description of the pheeno- 

 mena observed in the interval between the 21st of October and 

 the 11th of November; during which time occurred the va- 

 rious paroxysms of that eruption. The zigzag lightning began 

 to appear on the 22d, at two o'clock in the afternoon, not 

 proceeding from the pine of ashes, or from the great cloud of 

 smoke arising from it, but in a part of the atmosphere be- 

 tween both and occupied only by the ashes. The lightning 

 was not accompanied with any detonation. This electric phe- 

 nomenon, which increased as the violence of the eruption di- 

 minished, did not take place in the middle of a paroxysm, 

 but at the edges of the clouds of ashes. At a later period the 

 lightning was seen to emanate not only from the dusky clouds 

 or the air, but also from the earth, and even to traverse the 

 roads. 



Our authors discovered, by very simple but decisive expe- 

 riments, that the falling cinders were strongly and vitreously 

 electrified. Electric discharges were still seen from the sum- 

 mit of the mountain ; and the cinders, which were at first 

 gray, notwithstanding that their electricity remained the 

 same, altered to brown, and finally became of a reddish 

 colour. These red ashes falling in great abundance, and 

 spreading themselves thickly to a considerable distance, 

 caused great darkness. In addition to this, they observed 

 a strong smell of muriatic acid anil of muriate of iron, which 

 reached as far as Naples : had this not been the case, they 

 would yet have discovered from other effects the existence of 

 this acid in the ashes, which had the same day been the sub- 

 ject of their experiments. 



The pine presented a variety and a remarkable mutability 

 of colours, which are attributed by the authors to the refrac- 

 tions produced in the different currents of air through which 

 they passed. After an abundant shower of rain and cinders, 



the 



