EMANATIONS. 217 



pievak-nt opinion that dangerous shocks are only to be appre- 

 hended two or three times in the course of a century, cause 

 faint oscillations of the soil to be regarded in Lima with scarce- 

 ly more attention than a hail storm in the temperate zone. 



Having thus taken a general view of the activity the 

 inner life, as it were of the Earth, in respect to its internal 

 heat, its electro-magnetic tension, its emanation of light at the 

 poles, and its irregularly-recurring phenomena of motion, we 

 will now proceed to the consideration of the material products, 

 the chemical changes in the earth's surface, and the composi- 

 tion of the atmosphere, which are all dependent on planetary 

 vital activity. We see issue from the ground steam and 

 gaseous carbonic acid, almost always free from the admixture 

 of nitrogen ;* carbureted hydrogen gas, which has betji used 

 in the Chinese province Sse-tschuanf for several thousand 

 years, and recently in the village of Fredonia, in the State of 

 New York, United States, in cooking and for illumination ; 

 gulphuretcd hydrogen gas and sulphurous vapors ; and, more 

 rarely,! sulphurous and hydrochloric acids. Such effusions 



or, in November, December, January, May, and June. Experience 

 gives reason to expect the visitation of two desolating earthquakes in a 

 century. The period between the two is from forty to sixty years. The 

 most considerable catastrophes experienced in Lima since Europeans 

 have visited the west coast of South America happened in the years 

 1586, 1630, 1687, 1713, 1746, 1806. There is reason to fear that in the 

 course of a few years this city may be the prey of another such visita- 

 tion." Tschudi, op. cit.] Tr. 



* BischoPs comprehensive work, IVurmelehre det inneren Erdkdrpert. 



t On the Artesian fire-springs (Ho-tsing) in Chiua, and the ancient 

 i>e of portable gas (in bamboo canes) in the city of Khiung-tsheu, see 

 Klaproth, in my Asie Centrale, t. iii., p. 519-530. 



t Boussingault (Annaleg de Chimie, t. Iii., p. 181) observed no evolu- 

 tion of hydrochloric acid from the volcanoes of New Granada, while 

 Monticelk" found it in enormous quantity in the enaption of Vesuvius in 

 1813. 



$ [Of the gaseous compounds of sulphur, one, sulphurous acid, ap- 

 pears to predominate chiefly in volcanoes possessing a certain degree 

 of activity, while the other, sulphureted hydrogen, has been most fre- 

 quently perceived among those in a dormant condition. The occur- 

 rence of abundant exhalations of sulphuric acid, which have been hitli 

 erto noticed chiefly in extinct volcanoes, as, for instance, in a stream 

 issuing from that of Purace, between Bogota and Quito, from extinct 

 volcanoes in Java, is satisfactorily explained in a recent paper by M. 

 Dumas, Annales de Chimie, Dec., 1846. He shows that when sulphu- 

 reted hydrogen, at a temperature above 100 Fahr., and still better 

 when near 190, comes in contact with certain porous bodies, a cata- 

 lytic action is set up, by which water, sulphuric acid, and sulphur are 

 produced. Hence probably the vast deposits of sulphur, associated 

 with sulphates of lime and stront/an, which are met with in thd 

 western p:irts of Sicily.] 2V, 



VOL. I. K. 



