Neiv Outlines of Chemical Plulosophy. 327 



Xs\{ and IK parallel to AB. Make GH equal to gh, and IK to 

 ik, and through the points I,A,G and K,I3,H, draw by eye the 

 curved lines CIAGD and CKBIID, which will be the shape of 

 the required gore. In the diagram I have divided FAE and DC 

 into only four parts, for the sake of clearness: in practice, how- 

 ever, it is necessary to make use of eighteen or twenty divisions. 

 This method is equally applicable to any shape which may be 

 adopted, an advantage of which no other construction is pos- 

 sessed. 



JLXI. Nezv O21I lines of Chemical Philosophy. 

 ^ij Ez. Walker, Esq. of Lynn, Norfolk. 



[Continued from p. 211.] 



On the Leyden Phial. 



1 HE various hypotheses which have Iiecn invented to account 

 for the phenomena of the Leyden pliial j^lainly evince that the 

 subject still remains in some obscurity. Nor is this to be won- 

 dered at, when we reflect that the properties of the electrical 

 elements are so little understood, that philosophers are divided 

 in their opinions respecting them, Franklin, iEpinus, Robison, 

 and some others, have supposed that all electrical effects ai'e 

 produced by one fluid only ; whilst Du Faye, Symmer, Cigna, 

 Eeles, &c. maintain that there are two fluids, which exist to- 

 gether in all bodies, that thev counteract each other when united, 

 and can be made evident to the senses, only by their separation. 



Men are too apt to adopt the opinions of others without strict 

 examination. But it is an axiom in philosopHy, which ought 

 always to be kept in mind, that "no position should be assumed 

 as the basis of any reasoning whatever, except what has beerj 

 proved by incontestable facts." 



General Properties of Electricity. 



1. It has been demonstrated by an instrument, which may 

 be called the pendulum electrometer, described in a former pa- 

 per*, that the mechanical forces of those elements which pro- 

 duce a spark are equal, moving through each other; but the 

 spark so produced is not an elemerit, but the effect of those in- 

 visible clemetits which are brought into action by the motion 

 of the machine. But no spark can be produced unless those 

 elements pass through some conducting medium. 



2. The two electrical dements exist together in all bodies j 

 which may be called their natural state. 



* riiil, Mii^. vol. xlii. p. 163, and vol. xliii. p. 28^ 



X 4 3. Tw(» 



