General Literature^ 195 



which is also known; if to a point in the circumference of this 

 plate, an arm be affixed, which acts in the same plane with the 

 surface, it is required to know what resistance this plate will be 

 capable of making- against a force applied to this arm as a lever^ 

 considering the material, as well of the plate as of the arm and 

 surface, as a perfect mathematical abstraction ; that is to say, 

 as perfectly rigid or non-elastic, as infrangible or incapable of 

 breaking, S^c. ? 



2. A body being suspended from the extremity of a cord, the 

 other extremity of which is fixed to the roof of a room ; if this 

 body is made to describe an arc of a certain circle round the 

 fixed extremity ; and if, besides, a movement of projection is 

 given to it, — it is required to know the nature of the curve, or 

 rather double curvature, which this body will describe according 

 to the hypothesis — As is the resistance of the air, so is the 

 square of velocity ? 



3. If there is an identity between the forces which produce 

 the electrical phenomena, and those which produce the galvanid 

 phenomena, whence is it that we do not find a perfect accordance 

 between the former and the latter. 



4. Many modern authors believe in the identity of the che- 

 mical and galvanic forces, — it is required to prove the truth or 

 falsity of this opinion. 



5. What is the true chemical composition of sulphurets, as 

 well oxidized as hydrogenized, made according to the different 

 processes, and what are their uses in the arts ? 



The answers are to be supported, as far as possible, by new 

 facts and experiments easy of repetition. 



12. Death of M. Benedict Prcvost. — Announced in a letter to 

 the editors of the Bihliothique Universelle. 



Geneva, June 29, 1819. 

 MM. — I have received information of the death of a relation 

 whom you will regret as much as I do. J. Benedict Prevost, 

 born at Geneva, Aug. 7, 1755, died at Montauban, the 18th of 

 .lune, 1819. From his earliest youth he evinced a decided taste 

 for study. This taste was opposed by circumstances, and could 

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