3(>8 PHILOSOPHICAL TRANSACTIONS. [aNNO IJSQ. 



occasioned tremors, then universal convulsions, and lastly death. And 4 hours 

 afterwards, having opened the dog, the blood, which should have been coagu- 

 lated, was found fluid, both in the trunks of the veins, and at the ends of the 

 arteries. 



Exper. 21. — It has all the properties of sal ammoniac to that degree, that on 

 substituting this Vesuvian salt, instead of common sal ammoniac, the strongest 

 sort of aqua regia may be had for dissolving gold ; which experiment was made 

 with success by Mons. Lemery, in the academy of France. 



Exper. 11. — If a lump of the mineral matter be reduced to a fine powder, 

 and attentively viewed through a microscope, it appears very like the sand of 

 Ischia, and is very proper for writing-sand. Hence probably that sand is no- 

 thing else but the same matter for a long time comminuted by the action of 

 the sea. 



Exper. 13. — In some of the stones there appear some few veins of gold, in 

 others of silver, but insensible ; and in others, which are very heavy, there is 

 some antimony. 



Exper. 14. A great dispute arose in the academy on the rise of the (Mofete) 

 damps ; for what reason these should be seen only in the old strata of the mineral 

 substances, and not in the new, where by the action of the fire they ought to 

 issue ; which phenomenon, if I am not mistaken, may be accounted for in this 

 manner. As the cooling of the burning matter began at the surface, we may 

 think, that the more subtle heterogeneous particles, on the closing of the pores 

 at the surface, remained in quantities buried in the lower parts of the matter ; 

 which, in process of time, becoming acutangular and of deleterious figures, yet 

 cannot offend while imprisoned. But in new eruptions, when the shocks given 

 to the matter produce many fissures, the damps, meeting with less resistance 

 there, issue forth. As when the air is a long time pent up in some hollow, on 

 giving it vent, it generally comes out in a pernicious vapour. 



Exper. 25. It was observed, that the greatest shocks happened to such 

 things as stood exposed to the volcano ; but that those things which were not 

 thus exposed to it, received but faint shocks : a manifest sign, that the vibration 

 of the air had a great share in the shocks of the earth : which circumstance is 

 taken notice of by Borelli with respect to Mount Etna. 



An Abstract of a letter from an English Gentleman at Naples to his Friend in 

 London, containing an Account of the Eruption of Mount Fesuvius, May 18, 

 and the following Days, 1737, N. S. N° 455, p. 252. 



I was lodged for some time at Chaja, and afterwards at Fontina Medina, in 

 the face of this surprising mountain, and at 2 or 3 miles distance. 



