DE SAUSSURE AND READ. 307 



chemical action, which accompanied the process 

 of evaporation in most of their experiments. 

 Besides, they did not extend their researches to 

 the connexion of atmospheric electricity with 

 the phenomena of meteorology : they have there- 

 fore been very little attended to by philosophers. 



Lavoisier and Laplace found, that when water 

 was poured by drops into an iron vessel healed, 

 while the vessel communicated with an electro- 

 scope, it gave signs of positive electricity ; that 

 when dilute sulphuric or nitric acid was poured 

 upon iron filings, electricity was evolved ; also, 

 during the action of dilute sulphuric acid on 

 chalk, and during the combustion of charcoal. 

 Their experiments tend to shew the relation be- 

 tween chemical action and the evolution of elec- 

 tricity ; but throw very little light on the con- 

 nexion of electricity with evaporation. 



The most decisive results are those of De 

 Saussure and Mr. Read, who performed many 

 hundred experiments with the greatest care, for 

 the purpose of ascertaining the source of atmos- 

 pheric electricity ; the result of which led them 

 to the conclusion, that a perpetual circulation 

 of the electric fluid is kept up by means of 

 evaporation and condensation. 



De Saussure found that when water, spirit of 

 wine, and aether, were made to boil in silver, or 

 white porcelain vessels heated, and suspended 

 by silk cords, negative electricity wa obtained ; 



