by Dr. Van Marunu 317 



Jnches; after which it became ftationary. In a darkened 

 room, the electricity in vacuo appeared of a green Mh -yellow 

 colour. In the middle, where the electric ftream was. 

 ftronger, as well as at the furface of the phofphcwus, the 

 rays appeared of a very lively red colour. .After the paifage 

 of the eleclric current, the light did not continue a moment; 

 but the air produced retained its elafticity till the day follow- 

 ing. As foon as a little atmofpheric air was introduced to it, 

 the whole fpace above the mercury appeared luminous. Phof- 

 phorous gas was in all probability produced. The quantity, 

 however, was too (mall to be examined, though of the fame 

 kind as that defcribed by Gengembre in the Journal de Ply- 

 Jique for 1785. 



17. Experiments with a battery containing 550 fqu are feet 

 of coating. — This battery confifts of 100 jars, each twelve 

 inches in diameter, and from 23 to 23 inches in height. 

 They are coated to vithin four inches of the mouth, and 

 ftand at the diftance of half an inch from each other in four 

 boxes of equal lize. The boxes are five inches from each 

 other, and are connected at the top by four brafs rods, and 

 at the bottom by four plates of lead. In the middle jar 

 (lands a perpendicular tube, furnifhed with a ball fix inches 

 in diameter, and 24 holes, into which the tubes of the other 

 jars, an inch in diameter, are inferted : the lower ends of 

 thefe tubes are inferted in the balls of each jar. In the 

 jars themfelves there are wooden rods placed on (lands with 

 peculiar fupports, and on thefe brafs rods are (luck, fo that 

 nothing is cemented to the jars. When this battery had 

 been charged by 98 turns of the machine (100 turns made 

 it difcharge itfelf fpontaneoufly, by which means the jar 

 where the difcharge took place was pierced through,) an iron 

 wire, T ' inch in diameter and 24 ' inches long, was thrown 

 about to a great diftance in fmall red-hot globules. By a 

 companion with former experiments of this kind, it appeared 

 that the ftrength of the machine, by improvements made in 

 the cufhion, had been increafed five-fold. Dr. Van Marum 

 confidcrs the fufing of an iron wire, of a certain length and 

 ihicknefs, as the fureft means of ascertaining the flrength of 

 the (hock of a battery, In one experiment, by a (bock of the 



Vol. VJ.II. T t above 



