72 Scientific Intelligence 



Tertiary times. Outbursts of igneous rock — peridotite and tra- 

 chyte — accompany the disturbances. 



8. The Old Tungsten Mine at Tnimhull, Conn.; by Wm. H. 

 HoBBS. U. S. Geol. Survey, 22d Ann. Rept., Pt. 11, pp. 13-22. — 

 Tiiis report gives a short description of the geology of this min- 

 eral locality together with a detailed geological map of the 

 region. The 'deposit is of interest chiefly on account of the occur- 

 rence of the rare tungsten minerals, scheelite and wolframite, the 

 latter occurring as a pseudomorph of the former. Other charac- 

 teristic contact minerals are found associated with them. These 

 minerals are found at the contacts between a crj^stalline limestone 

 and two beds of hornblende-gneiss, which lie, one above and the 

 other below it. The hornblende-gneiss is of igneous origin hav- 

 ing the characteristics of a hornblende diorite, which, however, 

 becomes gneissoid and altered near its contacts with the lime- 

 stone. Considerable work has been done at the locality in the 

 effort to develop a paying tungsten mine, but with little success. 



w. E. F. 



9. Peculiar Character of the Eruption of Mt. Pelee, May 8th. 

 — The writer, in a communication to the Connecticut Academy 

 of Sciences, May 14, when only the first great eruption had 

 occurred, maintained that the destruction of St. Pierre was due 

 to the eruption of a great volume of exploding oxy-hydrogen 

 gases, due to the decomposition of water by contact with the 

 intensely heated lava deep within the volcano.* 



Subsequent investigations of the nature of the destruction 

 wrought there, and the character of the later eruptions, have 

 fully confirmed this view. 



At 2500° C. 50 per cent of the steam will be converted into 

 these explosive gases at ordinary pressures, but at the enormous 

 pressures within a volcano it would require a higher temperature 

 to effect this. But there is no doubt whatever that temperatures 

 above 3000° exist within many volcanoes. 



It is, therefore, only necessary to suppose that the highl}^ heated 

 lava, by bursting through the intervening rock, came into sudden 

 contact with a more or less extensive body of subterranean water, 

 or even with porous rocks saturated with water, in order to ex- 

 plain the sudden generation of explosive gases. 



If the subterranean waters thus converted into gases and 

 steam were sea- water, the chlorine of the salt would also be dis- 

 sociated from the sodium at the same or even lower temperatures, 

 and this gas would also form an explosive mixture with a part of 

 the hydrogen. By their union hydrochloric acid gas would be 

 produced, which is a highl}^ irritating, poisonous and suffocating 

 gas, powerful enough, even when present in small quantities, to 

 destroy animal and vegetable life, as has happened in several of 

 the eruptions of Vesuvius and other volcanoes near the sea. 

 However, in the case of St. Pierre, nearly all the people were 

 probably killed instantaneously by the outburst of intensely hot 



* See Science, May 16, 1902. 



