256 Professor Wartmann on the relations 



into the camera by a prism of flint glass cut by Fraunhofer 

 himself. These experiments, repeated at different intervals 

 and continued for a sufficient time, have all given the same 

 negative results. 



For greater certainty I made the trial in another manner, 

 employing electricity of tension. A tube of thick glass, m, 015 

 in diameter, and m, 07 in length, was fixed vertically in a box 

 blackened within and without. A stopper above was traversed 

 by a copper wire of m, 001 diameter, communicating metalli- 

 cally with a very thick rod of brass passing through the roof 

 of the box and terminating on the outside by a ball of the same 

 metal m, 03 diameter. Another stopper, closing the tube be- 

 low, admitted a similar wire, which passed out at one angle 

 of the case and extended thence to the ground by means of a 

 chain. The interval between the two wires was made to vary 

 from 1 to 6 millimetres, according to circumstances. The 

 tube was filled in succession with alcohol, oil of turpentine, 

 carburet of sulphur and olive oil, either pure, or mixed in 

 different proportions. A lateral door serving to shut the box 

 was pierced with a vertical slit m, 003 wide by m, 02 high, 

 the centre of which corresponded to the interval between the 

 wires in the tube. Finally, in the same horizontal plane, the 

 fixed partition had been pierced opposite to a little circular 

 opening which was shut by an ivory screw. 



By making sparks of greater or less strength pass through 

 this apparatus, we found that the greatest distance at which 

 the ball should be placed from the conductor for the maximum 

 effect, depended on the nature of the liquid to be decomposed, 

 on the interval between the wire conductors*, and on the 

 energy of the machine. In each experiment, when the pro- 

 per distance had been attained, it remained invariable, whe- 

 ther the decomposition took place in the thickest darkness, or 

 in the bright light of the sun, or whether the liquid was illu- 

 minated through the slit, by colouring it with different tints, 

 by means of coloured glasses, or by projecting upon it the 

 varied tints of the spectrum. The small hole opposite to the 

 slit served to examine the spark, to become assured of its 

 passage and of its decomposing energy. 



I remarked that the same number of turns of the plate 

 machine were necessary in order that the tension of the accu- 

 mulated electricity should be sufficient to make the spark dart 

 upon the ball placed at four or five centimetres distance, 

 whatever was the condition of the light in the experiment. 



* The experiment also indicates that this decomposition proceeds suc- 

 cessfully only when the extremities of the wires are pointed, and not ter- 

 minated by balls. 



