196 Nciv Eleflric Experiments. 



engaged from it. To afcertain the truth of this conjecture, 

 Van Marum introduced a thermometer into a receiver be- 

 tween two condu&ors, and, having exhaufted part of the air, 

 threw the ele&ric ftream on the bulb. The thermometer, 

 however, rofe higher than in the open air, or to 120 degrees. 

 The air in the receiver had been rarefied lo 7 \. That he might 

 proceed with ftill greater certainty, he performed the experi- 

 ment in oxygen gas and azotic ga6 rarefied in the fame de- 

 gree ; but in both cafes the thermometer rofe as much as 

 before. Van Marum thought he fhould find another proof 

 of the above opinion, by trying whether the electric matter 

 was able to convert aqueous liquids into expanfible fluids; 

 for, as the elafticity of all fuch fluids is afcribed to their mix- 

 ture with caloric, it feemed reafonable to conclude that caloric 

 muft exift wherever it is poffible to form expanfible fluids. 

 Prieftley converted vitriolic ether, by means of eleftric fparks, 

 into inflammable gas, and obtained the like remit from oil 

 of turpentine, Ipirit of wine, and ammonia ; but Dr. Van 

 Marum,, froth theft fubftances, obtained oniv very little gas, 

 though his machine worked with much greater itrength, and 

 the fmall quantity which was obtained was again foon ab- 

 forbed ; and therefore he is of opinion that thefe gafes were 

 Tather expelled from the above fubftances by the electricity, 

 than prepared by it from their component parts. With ether 

 and ammonia the quantity was a little larger; but, as theft 

 fubftances are exceedingly volatile, it could not be determined 

 with certainly that the air was produced from the caloric of 

 the electric matter; becaufe feveral liquids acquire their 

 liquid form merely from the preffure of the atmofphcre. 

 Dr. Van Marum conceived the idea of making the experi- 

 ments in vacuo with other fluids, becaufe in that cafe a fmall 

 quantity of caloric might produce air. For this purpofe he 

 employed the Torricellian vacuum, and, having put platina 

 wires into feveral barometric tubes ' inch in diameter, fuftd 

 the glafs around them at a lamp ; he then inverted the tubes, 

 and filled them with quickfilver in fuch a manner that * inch 

 of each remained empty. Into this empty fpace he intro- 

 duced the fluids, through which the elcftric fparks were to 

 be conveyed ; then clofed the aperture, and again inverted 



the 



