Dr. Harems Defta^-rator and Calorimotor. 109 



aeriform state, acted as a supporter of combustion on the 

 metal/' 



Tbis paragraph, at the time of perusing it, excited in my 

 mind a lively interest, and a strong wish to see so fine a re- 

 sult, as the fusion of charcoal, confirmed by an experiment 

 admitting of no question- What you threw out by way of 

 surmise, and without positively affirming it, I think I am 

 now able to substantiate. 



During the three last weeks of March, I was much occu- 

 pied with your deflagrator. The medium of communica- 

 tion, between the poles, was generally, charcoal prepared 

 for the purpose, by intensely igniting pieces of very dry 

 mahogany, buried in a crucible, beneath white siliceous sand. 

 The pieces of charcoal thus prepared, were about half an 

 inch in diameter, and from one and h^lf inch, to three inches 

 in length ; they were made, as usual, to taper to a point, and 

 the cylindrical ends were placed in the sockets, connected 

 with the flexible lead tubes, which form the polar termina- 

 tions of the series. 



The metallic coils of the deflagrator, being immersed, on 

 bringing the charcoal points into contact, and then with- 

 drawing them a little, the most intense ignition took place, 

 and I was surprised to observe, that the charcoal point of 

 the positive pole^ instantly shot out, in the direction of tlie 

 longer axis, and thus grew rapidly in length ; it usually in- 

 creased, from the 10th to the 8th of an inch, and in some 

 instances attained nearly l-4th of an inch in length, before 

 it broke off and fell. Yesterday and today, I have careful- 

 ly repeated these experiments, and in no instance, has this 

 shoot from the positiv^e pole failed to appear. It continues 

 to increase rapidly, as long as the contiguous point*? of char- 

 coal are held w^ith such care, that they do not strike against 

 each other. When they impinge witli a slight shock, then 

 the projecting shoot or knob breaks off and falls, and is in- 

 stantly succeeded by another. The form of the projecting 

 shoot, is sometimes cylindrical, but more generally it is that 

 of a knob, connected with the main piece of charcoal, by a 

 slender neck, much resembling some stalagmites. It is al- 

 ways a clear addition to the length of the charcoal, which 

 does not suffer any waste except on the parts, laterally con- 

 tiguous to the projecting point. 



