Roj/al Society. 447 



mosphere of the eruption. To leeward of the volcano, the sea was 

 much discoloured by the admixture of ashes and fine dust, and an 

 abundance of light cinders were floating on its surface. Even when 

 the author was enveloped in the dark cloud of ashes falling from the 

 volcano, not the smallest odour of bitumen, of sulphuretted hydrogen, 

 or of sulphureous or any other acid, was perceptible ; nor was any 

 inconvenience felt in respiration. No appearance of flame, and but 

 little light, was exhibited during these eruptions. 



The solid products ejected from the volcano appeared, on examina- 

 tion, to differ more in form than in chemical composition ; and were 

 found to consist of alumina, lime, magnesia, and silica, coloured by 

 protoxide of iron, and without any potash. With the exception of 

 small masses of vesicular basalt, similar to the common lava of Etna 

 and Vesuvius, these materials exhibited no crystalline structure. The 

 water taken from the crater appeared to consist of sea-water holding 

 in suspension a fine dust, together with filaments resembling vegetable 

 fibres, which the author supposes to have been derived from sea-weed 

 drawn into the water. The saline ingredients of this water difl^iered 

 from that of the Mediterranean, chiefly in containing more sulphate 

 of lime, and a little alumina, oxide of iron, and a trace of oxide of 

 manganese ; all these in combination with an acid, probably the sul- 

 phuric or muriatic, and a notable portion of hyposulphite of lime and 

 magnesia. He could not detect in it any free acid or alkali, or the 

 presence, even in combination, of any potash or ammonia, or nitric 

 acid, nor the slightest trace of bromine or iodine. The gas emitted 

 by the volcano appeared, as far as could be determined from an ex- 

 amination of two specimen-;, to consist chiefly of carbonic acid, with 

 a trace of sulphuretted hydrogen. 



The author observes in conclusion, that the result.s of his inquiry 

 are almost entirely of a negative kind ; and in this respect correspond 

 with those obtained by Sir Humphry Davy, with respect to Vesuvius, 

 and which are described in his paper" On thePhsenomena ofVolcanos," 

 published in the Philosophical Transactions for 1828. They accord- 

 ingly tend to corroborate the simple hypothesis there adopted in expla- 

 nation of the phaenomena of volcanic action ; namely, that of the ex- 

 istence of an ignited nucleus of fluid matter, occasionally forced 

 through the cooled crust of the earth by the expansive power of steam 

 and gas ; and they militate strongly against the hypothesis of the che- 

 mical origin of volcanos, and of their being attended by a decomposi- 

 tion of water by the metallic bases of the earths and alkalies. 



A drawing of the volcano in its active state of eruption accompanied 

 the paper, together with a plan, and views of the island. 



January 12, 1832.— The Bakerian Lecture for 1S32, entitled 

 " Experimental Researches in Electricity — Second Series," by Mi- 

 chael Faraday, Esq. F.R.S. was read. 



The success of the author in exhibiting the evolution of elec- 

 tricity by induction from ordinary magnets, led him to conclude 

 that similar effects might be obtained from the magnetism of the 

 earth, and even to an extent that might render it available in the 

 construction of new electrical machines*. These expectations have 

 been fully realized; and the researches which establish the in- 

 * See p. 407, 465. 



fluence 



