308 EXPERIMENTS OF DE SAUSSURE. 



but when a piece of red hot iron was thrown into 

 a vessel containing a small quantity of water, 

 positive electricity was strongly developed. He 

 supposed that the vast quantities of electricity 

 discharged from volcanos, was generated by the 

 action of so great a heat on waters that find their 

 way to those immense furnaces. In all such 

 cases, it is disengaged chiefly by chemical action, 

 as will be noticed when I come to treat of voltaic 

 electricity and volcanic forces. 



The following experiments of De Saussure 

 shew, that aqueous vapour, however produced, 

 contains electricity. He caused water to boil in 

 a coffee-pot, by placing it on an insulated 

 chauffer (heater), when the coffee-pot was elec- 

 trified minus, during the condensation of the 

 vapour. He varied the experiment, by causing 

 the vapour of boiling water to pass into the cap 

 of an insulated alembic, to which he applied 

 snow, causing a condensation of the vapour con- 

 tained within it, when the apparatus became 

 electrified minus, or negative. The same effect 

 was produced in a more remarkable manner, by 

 applying a mixture of common salt and snow as 

 a refrigerent. He observes, that in all such cases, 

 electricity is disengaged from the vapour, and 

 conducted to the metallic vessel during the pro- 

 cess of condensation. (Voyages dans les Alpes, 

 tome ii. 251.) 



De Saussure adds, that the electric fluid is 



