180 Dr. Andrews 07i the Conducting Pcmer of certain Flames 



of tlieir higher conductnig power, feeble voltaic combinations 

 must be employed to discover it. 



One pole of a battery of a single pair of plates, immersed 

 in dilute sulphuric acid, was connected with the brass tube of 

 an Argand gas lamp, and the other pole was attached to a coil 

 of platina wire which rested upon the top of the flame. When 

 the latter pole was positive, the current passed ; when nega- 

 tive, it was interrupted. The same battery being employed, 

 one pole was brought into contact with the ignited charcoal 

 of a charcoal fire, and the other with the flame; the current 

 passetl, whether the pole in the flame was positive or negative, 

 but much more readily when it was positive. 



In the action of the magneto-electrical machine, as it is now 

 constructed, the direction of the current is reversed at every 

 semi-revolution of the soft iron armature; and from this cir- 

 cumstance the elements of compound bodies that are decom- 

 posed by it cannot be obtained in a separate state. By sub- 

 stituting this machine for the galvanic battery, any difference 

 in the transmission of two currents perfectly similar, but tend- 

 ing to move in opposite directions, could be observed without 

 altering the arrangement of the apparatus ; and thus I expected 

 not only to verify in a striking manner the preceding results, 

 but also to obtain from the magnet the effects of a continuous 

 electrical current flowing in one direction. 



The electricity of the machine I employed had sufficient 

 tension to decompose water, to burn metallic leaves, and to 

 cause considerable shocks; but it did not pass sensibly through 

 heated air even when the most favourable arrangement was 

 adopted. By substituting the flame of charcoal for heated air 

 the peculiar property of flame in conducting voltaic electricity 

 was found also to exist in the case of electricity obtained from 

 the magnet. 



The i^oints by which the sparks are usually procured from 

 the machine were replaced by a circular disk, and a copper 

 wire was introduced into each of the cups of mercury in which 

 the disks revolved. One of these was connected with a platina 

 wire placed over a charcoal fire at such a distance, that when 

 the fire was urged by bellows it became surrounded by the 

 flame; the other wire had a platina termination, and rested 

 on a slip of paper moistened with the solution of iodide of po- 

 tassium. The circuit was completed by inserting one extremity 

 of a wire of platina into the side of the furnace so as to bring 

 it into contact with the charcoal, while the other extremity was 

 placed upon the slip of moistened paper. By this arrange- 

 ment the currents developed by the rotation of the machine 

 would be obliged to pass downwards through the flame to the 



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