107 



may be viewed as alcohol, the oxygen of which has been replaced 

 by sulphur, as in the following formulte : 



C4 H, Og = Alcohol. C^ Hg Sg = Mercaptan. 



The pyroxylic spirit of Dumas and Peligot being extremely analo* 

 gous to alcohol, Dr Gregory examined whether this analogy ex- 

 tended to the production of a compound analogous to Mercaptan ; 

 and, by substituting pyroxylic spirit for alcohol, be obtained this 

 compound, which, although in most of its properties closely resem- 

 bling mercaptan, is distinguished from it by a greater degree of 

 volatility, boiling at 70° F., while mercaptan boils at 185° F. The 

 following formulae exhibit the composition of the pyroxylic spirit, 

 according to Dumas and Peligot, and the probable composition of 

 the new liquid : 



C^ H^ O2 = Pyroxylic Spirit. C^ H^ S^ = New Liquid. 



The new liquid has, like mercaptan, a most insupportable alliaceous 

 odour, and exercises an action on red oxide of mercury similar to 

 that from which the name Mercaptan is derived. 



4. On a curious Phenomenon observed in the Island of Ce- 

 phalonia, and on the proximate cause of Earthquakes in 

 the Ionian Islands. By Dr John Davy. Communicated 

 in a letter to Professor Forbes. 



Dr Davy communicates the description of certain streams of sea- 

 water which appear to be constantly flowing into the interior of 

 the earth, by four openings, near the town of Argostoli, in Cepha- 

 lonia. These are now applied as sources of mechanical power. Dr 

 Davy views this curious fact as probably related to the very re- 

 markable local earthquakes which affect the Ionian Islands, and 

 which appear to be disconnected with any volcanic appearances, or 

 even the occurrence of trap-rocks. Dr Davy conceives that these 

 phenomena may be attributable to the absorption of this quantity 

 of sea-water constantly received into the land by the marly beds 

 which occur in Cephalonia. This absorption, Dr Davy concludes 

 from direct experiment, may produce an enlargement of the vo- 

 lume of the marl. This supposition is supported by the remarkable 

 fact, that, in the Ionian Islands generally, these earthquakes occur 

 entirely in the low and marly parts of those islands, and never in 

 those parts connected with solid rock. 



