206 Miscellanies. 



platinum portions of the wire, and I had greatly to reduce its length be- 

 fore the experiment would succeed. Indeed so little satisfactory did the 

 experiment appear to be, that I was going to substitute in its place, that of 

 shewing the ignition of a plain piece of platinum wire ; when recollecting 

 that whenever the poles of a battery in action come in contact, or the 

 contact is broken, a spark is given out; I thought that if the con- 

 tacts of the alternate links could be broken, or even a little disturbed, they 

 would shew the electric spark at the points of contact. 



To try if this was correct, I rejoined the links of the chain of platinum 

 and silver wire, making it about one and a half or two feet long. Each 

 end was silver wire, to attach it to the poles of the battery. The 

 battery being in action, and its poles connected by a copper wire ; the 

 chain was suspended from the poles in a festoon. The copper wire be- 

 ing removed, on giving the festoon a short irregular motion, by striking 

 it on the under or convex side, with a splint of wood, a succession of 

 sparks was produced, of a brilliant and imposing appearance. This will 

 continue, the battery being in action, as long as the proper motion is giv- 

 en to the chain. This motion can be so managed, as to give out sparks 

 in a slow or a rapid manner. 



This experiment was repeated in the evening before the members of the 

 Institute ; and the lights being nearly extinguished, it shewed the experi- 

 ment to better advantage than by day light. The battery that was used 

 is the one belonging to the Institute, of about 200 double plates ; I believe 

 you have used it, on one occasion or more, when in this city. 



Will you be kind enough to repeat this experiment, if not interfering 

 with your arrangements. 



V S 



Note. — It is found better to use the copper wire bent as in the above, than 

 to twist it around the poles, as it could be detached without trouble, or 

 danger of receiving shocks. 



3. On a new pyrogenic acid, by M. S. Baup. — M. Baup has discov- 

 ered that, independently of a spirituous liquid and a bituminous oil, pyro- 

 citric acid is not the only product of the distillation of citric acid, but 

 in addition a second acid is formed which hitherto has not been remark- 

 ed. It is obtained by evaporating the liquid resulting from the dis- 

 tillation of citric acid, until small acicular crystals are observed ; when 

 these crystals are to be separated preparatory to obtaining the new 



