A HISTORY OF SCIENCE 



tigations in every one of the six subjects admitted by 

 that institution as worthy of recognition. Dufay up- 

 held his reputation in this new field of science, making 

 many discoveries and correcting many mistakes of 

 former observers. In this work also he proved him- 

 self a great diplomat by remaining on terms of inti- 

 mate friendship with Dr. Gray a thing that few 

 people were able to do. 



Almost his first step was to overthrow the belief 

 that certain bodies are "electrics" and others "non- 

 electrics" that is, that some substances when rubbed 

 show certain peculiarities in attracting pieces of paper 

 and foil which others do not. Dufay proved that all 

 bodies possess this quality in a certain degree. 



" I have found that all bodies (metallic, soft, or 

 fluid ones excepted)," he says, "may be made electric 

 by first heating them more or less and then rubbing 

 them on any sort of cloth. So that all kinds of stones, 

 as well precious as common, all kinds of wood, and, in 

 general, everything that I have made trial of, became 

 electric by heating and rubbing, except such bodies as 

 grow soft by heat, as the gums, which dissolve in water, 

 glue, and such like substances. Tis also to be re- 

 marked that the hardest stones or marbles require 

 more chafing or heating than others, and that the same 

 rule obtains with regard to the woods; so that box, 

 lignum vitce, and such others must be chafed almost to 

 the degree of browning, whereas fir, lime-tree, and cork 

 require but a moderate heat. 



"Having read in one of Mr. Gray's letters that 

 water may be made electrical by holding the excited 

 glass tube near it (a dish of water being fixed to a 



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