1820.] Proceedings of Philosophical Societies. 453 



I have pointed out these ramifications, and whom I have fre- 

 quently called upon to explain how this direction of all the 

 branches of a ray towards one side can happen, supposing, 

 according lo their hypothesis, the ray was produced by two anta- 

 gonist fluids proceeding from opposite sides, have never hitherto 

 attempted a reply. 



The question proposed by the first class of the Institute of 

 the Sciences at Amsterdam, at its last public sitting, on Oct, 8, 

 was as follows : 



Are there any experiments directly proving the system now 

 maintained by a great number of philosophers, viz. that electrical 

 phenomena are occasioned by two fluids l and, in that case, what 

 are they ? Or are there, on the contrary, decisive experiments in 

 favour of Franklin's theory, which was generally adopted, until 

 the commencement of the present century, by the first philoso- 

 phers, viz. that electric phenomena are produced by a single 

 fluid ? It is desired that in the examination of different experi- 

 ments particular attention may be paid to what has been seen, 

 with the grand Teylerian apparatus at Haerlem ; that is, that 

 the electric spark, carried to a certain degree of force, appears to 

 furnish, by its ramifications, certain indications that it keeps one 

 single direction throughout its whole course, whether the conduc- 

 tor be electrified positively or negatively;* and itis requested that 

 it be examined whether this experiment furnishes a complete 

 proof, that these electrical phenomena are produced by the cur- 

 rent of a single fluid, or if this direction of the ray can be clearly 

 explained by the theory of the electrical phenomena not being 

 produced by a single fluid, but by the junction of two distinct 

 fluids, of a different nature, and acting oppositely ; and if there 

 be no decisive experiments directly proving the system of two 

 fluids, it is asked why conclusions deduced from formulae 

 founded on this system should appear to accord with experience, 

 and where it is that the error lies. 



Article IX. 



Proceedings of Philosophical Societies. 



ROYAL SOCIETY. 



Nov. 9. — The Society resumed its meetings, when a letter 

 from M. Ampere was read, on the subject of the Magnetic Effects 

 produced by the Voltaic Electricity. 



There was also a paper, by Sir E. Home, read, entitled " On 

 the Black Rete Mucosum of the Negro, being a Defence against 



• Sfte M. Van Marum's work, entitled, " Experiences faites par la grandji 

 Machiae £lcctrii[ue de Teylcr." Harlem, 1785. 



