50 M. Becquerel on the electrical proj)erties of Tourmaline, 



Art. VIII. — 071 the Electrical Froperties of the Tourmaline.* 

 By M. Becquerel. 



Jl HiLOSOPHEKS attribute to molecular attraction an electrical 

 origin, though they are still ignorant where the electrical forces 

 reside by which it is produced. Among the hypotheses, more 

 or less ingenious, contrived for explaining this mystery, there 

 is one which considers the atoms of bodies to be endowed with 

 electrical properties analogous to those which heat developes in 

 the tourmaline. This manner of viewing it rests solely upon 

 conjecture ; and in order to verify it, since we cainiot isolate an 

 atom in order to study its physical properties, we must exa- 

 mine with the utmost care all the electrical modifications which 

 the tourmaline exhibits when its temperature is varied, as well 

 as the laws which regulate them, and see if it be not possible 

 to draw inferences more or less favourable to an electro-che- 

 mical theory. Such is the philosophical object which I had in 

 view in the researches which I have undertaken upon the tour- 

 maline. 



The electrical properties of this remarkable stone have for 

 a long time engaged much attention. Some philosophers have 

 even asserted that it was known to the ancients under the name 

 of Lyncurium, given to it by Theophrastus ; but upon examin- 

 ing with attention the characters assigned to it by this philoso- 

 pher, we can find none which belong to it in particular. It is 

 known for certain, however, that from time immemorial it was 

 observed in India and in the Island of Ceylon, that this stone, 

 when thrown into the fire, had the property of attracting the 

 cinders. The Dutch, to whom the natives of the country 

 showed the phenomenon, were the first who made it known in 

 Europe. Lemery, in 1717, presented to the Academy of Sci- 

 ences a tourmaline brought from Ceylon, which possessed the 

 property, he said, of attracting and repelling light bodies. 

 More recently the Duke of Noya, iEpinus, Wilson, Priestley 

 and other philosophers examined the attractive power of this 

 stone. Many of them obtained contradictory results, which 



• Read to the Royal Academy of Sciences, 14th Jan. 1828. Translated 

 from the Annales de Chimie, Jan. 1828. torn, xxxvii, p. 1. See this Jour- 

 nal, No. 16, p. 365. 



