NATURAL PHILOSOPHY. IGl 



to be correct. To determine the effect of a cooling surface on 

 the flaming spark, a hole one and one-half inches in diameter 

 was bored through a thick l)lock of Wenliam Lake ice, and the 

 spark passed through the air in the tube of ice ; no change took 

 place, and the spark was still a flaming one. 



"AVhen the spark was received on the ice, it lost its flaming 

 character, and became thin and wiry, spreading out in all direc- 

 tions. 



*'If the discharging wires were tipped with ice, the spark was 

 always flaming when any thickness of air intervened between 

 them. Even over the ice, if the spark passed a fraction of an 

 inch above the surface, it was always a flaming one, but changed 

 to the thin spark when the point of the discharging wire was 

 thrust into the ice. 



*'If one of the discharMn": wires of the o^reat coil is brouofht 

 to the centre of a large swing looking-glass, and the other wire 

 connected with the amalgam at the back, the sparks are thin and 

 wiry, arborescent, and very bright ; the crackling noise of these 

 discharges being quite different- from that of the heavy thud or 

 blow delivered by the flaming spark. 



'* When the discharging wire is brought close to the frame of 

 the looking-glass, or if a sufficiimt thickness of air intervenes, 

 the spark again becomes flaming; or, as sometimes occurs, if the 

 discharging wire is placed about 5 inches from the frame, the 

 spark is partly flaming and partly wiry, that is, when it impinges 

 on the glass. 



"The spectrum is a continuous one with the sodium line. 



"When the blast of air is used, and the wiry sparks made 

 apparent, then the nitrogen line appears. 



"The flaming spark has been ascribed by some experienced 

 observers to the incandescence of the dust in the air, and espe- 

 cially sodium chloride. 



"To ascertain whether the * flaming spark' could be obtained 

 with a small number of cells, the large Bunsen's battery was 

 reduced to 3 cells, and it was found that no appreciable spark 

 could be produced when the whole primary wire was used with 

 less than 5 cells. 



"By reducing the length of the primary wire, and using the 

 4 divisions separately, with 5 cells, the spark was wiry, and 

 varied from 4^ to 6^ inches ; with 10 cells it was wiry, and varied 

 from 8J to 9| ; in the latter the spark was slightly flaming. With 

 15 cells the spark was slightly flaming, and varied from 10 inches 

 to 11§ inches. With 20 cells a flaming spark, varying from 11^ 

 inches to 12^ inches, was obtained. 



"When the two wires from the secondary coil are placed in 

 water, no spark is perceptible, even when the wire was brought 

 very close together, until they touch. 



" If the negative wire is passed through a cork, on which a 

 glass tube (a lamp glass) is flxed containing a depth of 5 inches 

 of water, and the positive wire is brought within half an inch of 

 the surface of the water in the tube, it becomes red-hot, and if 

 drawn furtlier away from the surface, the upper part of the 



