ARTICLE Iir. 



On the Extrication of the AlkalifiaUe Metals, Barium, Strontium, and Calcium. 

 By Robert Hare, M. D., Professor of Chemistry in the University of Pemi- 

 sylvania. Read October 4, 1839. 



In the autumn of 1820, I devised an innovation in the mechanism and in 

 the mode of completing the circuit of an extensive voltaic series. Previously to 

 that time, in using any form of the voltaic battery, the circuit had always been 

 completed by making a communication between the electrodes,* after the sub- 

 mersion of the plates. In the case of the deflagrator, the electrodes might be 

 made to communicate before the immersion of the plates, the circuit being 

 completed by their immersion. Or, in case the electrodes should not be in con- 

 tact before immersion, the operator was enabled to bring them together so 

 nearly about the same time, as to avail himself of the pre-eminently energetic 

 action which immediately succeeds the encounter between the plates and the 

 solvent. 



Fourteen years had elapsed, during which I had the regret of perceiving 

 that the advantages of the deflagrator were not sufiiciently estimated in Europe, 

 when, about the year 1835, the celebrated Faraday, f while investigating the 

 principles upon which galvanic apparatus should be constructed, came to a 

 conclusion that the deflagrator eminently associated the requisites of which he 



* Agreeably to the suggestion of Faraday, I use the word electrode, for the pole of a voltaic 

 series ; also anode, for the positive pole, and cathode for the negative pole. 

 ^ See London and Edinburgh Philosophical Magazine and Journal, vol. viii., for 1836, p. 114. 



