New Electric Experiments. 195 



electrified, 1S0; and when electrified, 165 grains. A "boy 

 of eight years and a half loll unelectriried 430, and when 

 electrified 290. Another of nine years, unelectriiied 170, 

 electrified 240. As the laft boy was exceedingly quiet during 

 the experiment, it was thought that the incrcafe was the 

 confequence of electricity 5 on this account he was feveral 

 times fubjeeted to the experiment, and the refults were in the 

 uneleetrified Itate 550; in the electric 390, 330 and 270, 

 ^50 and 420. In molt of the experiments it appeared that 

 there was rather a decreafe. 



3. Refpe&ing the irritability of the veflels of vegetables as 

 the caufe of the afcent and defcent of fap. — The remit of 

 thefe experiments (viz. that from the cut (terns of different 

 kinds of euphorbia, and other plants of the like nature, when 

 expofed to ft rung fparks, no more lap flows, as, by the irri- 

 tabilitv of the fibres being deftroyed, the veffels are rendered 

 incapable of contracting themfelves) is already well known. 



4. Rcfpecting the existence of caloric in the electric matter. 

 — Dr. Van Marum caufed a conductor of very thin brafs 

 plate, five inches in diameter and eleven inches in length, 

 to be constructed with a cavity in the middle, in which he 

 placed the bulb of a very fenfible thermometer, and fufpended 

 it by filk firings near the conductor of the large machine. 

 Neither by pofitive nor negative electricity, however, did 

 their appear the leaft fign of the thermometer rifmg. As 

 charcoal is an excellent conductor, he introduced the bulb of 

 the thermometer into a cavity made in a piece of that fub- 

 ftance; but (till there was no fign of heat, from this it 

 appears to him, that the figns of heat exhibited by electricity 

 may arife only from the great velocity with which the electric 

 matter paflea through bodies, and that the fufion or eombuf- 

 tion of thefe bodies thence refulting may be occafioned by 

 the friction thus produced. If a ftrcam of electric matter he 

 conveyed to the bulb of a thermometer, it immediately rifes 

 as Van. Marum found, and often from 80 of Fahrenheit 

 <o 100 and more: but this experiment cannot be confidered 

 a-; a proof of the exiftencc of caloric in the electric matter, 

 as Cavcnuidl found the electric current decompofes the at* 

 niofpheric air, by which means l'omc caloric may be diij. 



C c i engage^! 



