IGO ANNUAL OF SCIENTIFIC DISCOVERY. 



*' Experiments wero now tried to ascertain whether any in- 

 crease in the length of the spark could be oljtained l)y arranging 

 the battery and the ])riniary coil lor quantit}', but no material 

 advantage was obtained Ijy tiiis arrangement; even where 3 

 groups of cells were connected, a decrease in tlie length of the 

 spark is observed when compared with the 45 or 50 cells arranged 

 for intensity, tiie diUcrence being as '20 to 28. 



" Tiie si)ark obtained from the large coil is tliiok and llame- 

 like in its appearance, and therefore it will be alluded to as the 

 ' flaming spark.' 



"AVhen the discharging-point and circular plate are brought 

 within 6 or 7 inches of each other, the flaming nature of the spark 

 becomes still more apparent. 



*' Two light-yellow flames curving upwards appear to connect 

 the opposite poles. If a blast of air from a powerful bellows is 

 directed against a flaming spark, the flaming portion can be 

 blown away and increased in area, and thin, wiry sparks are now 

 seen darting through it, sometimes in one continuous stream, at 

 another time divided into three or more sparks, all following the 

 direction in which the flame is blown. 



*' The flaming spark is very hot, and, if passed through as- 

 bestos (supported on an insulating pillar), quickly causes the 

 latter to become red-hot. 



" When powdered charcoal is shaken from a pepper-box into 

 the flaming spark in a vertical line and in considerable quantities, 

 the greater i)art of the light is obscured, and the whole form of 

 the flaming spark presents the appearance of a ijlack cloud with 

 a line of brightly ignited particles fringing the bottom parts. If 

 the charcoal is dusted through in small (juantities, each j)article 

 becomes ignited, like blowing charcoal into a hydrogen flame. 



"When the flaming spark is directed on to a glass plate, upoa 

 which a little solution of lithium cidoride is placed, the latter 

 colors the flame upwards to the height of 3 or 4 inches in the 

 most beautiful manner ; and if the point of the discharge is 

 tipped with i)aper, or sponge moistened with a little solution of 

 sodium chloride, the two colors (the yellow from the salt, and the 

 crimson from the lithium) meet each other, a neutral point being 

 found about half way, and thus illustrating apparently the dual 

 character of electricity, and that -f- passes to — electrical, and 

 vice versa. 



•*Tiie flaming spark can be obtained in perfectly dry air. 



"While passing through common air, if l)l()wn against a sheet 

 of damp litmus paper, the latter is rapidly changed red. In 

 order to ascertain whether the acid proihict was nitric acid, the 

 flaming spark (9 or 10 inches in length) was j)assed through a 

 tube connected by a cork and bent tube with a l)ottle containing 

 distilled water, from which another tul»e passed to the air-pump. 

 On drawing the air slowly over the spark, and passing the former 

 into the bottle, nitric acid was obtained in large quantities, so 

 much so that it could be detected by the smell and taste as well 

 as by the ordinary tests. The })opular notion that nitric acid is 

 always produced during a thunder-storm would therefore appear 



