Apparatus and Processes. 247 



This was demonstrated by attaching one pole of the series of sev»- 

 en hundred pairs to one leg of the magnet, while the other pole was 

 made first to touch the end of the other leg, and then retracted so 

 as to produce the vivid discharge of igneous matter, well known 

 to ensue under such circumstances. The discharge being thus es- 

 tablished, it was arrested, as soon as a calorimotor was made to act 

 upon the coils. The experiment was reiterated again, and again, with 

 the same result. 



About two years ago, I stated that taking the iron of an electro- 

 magnet into the circuit of a calorimotor fifty times larger than that 

 used for the coils, the attractive power, though enfeebled, was not 

 destroyed. I have lately ascertained that a knitting needle may be 

 magnetized and have its poles reversed while subjected to a direct 

 current from the same large instrument, the inductive magnetic power 

 being meanwhile due to a calorimotor of not more than a fiftieth of 

 the size. 



I avail myself of this opportunity of mentioning that fused caout- 

 chouc inflames in concentrated nitric acid. 



This result was unexpected by me, never having met with any ac- 

 count of this habitude, and which I presume had not been before no- 

 ticed. 



Art. IV. — Apparatus and Processes; by Robert Hare, M. D., 



Professor of Chemistry in the University of Pennsylvania. 



Communicated by the author. 



1, Apparatus for evolving Silicon from Fluo-silicic Acid Gas. 



Into a stout mahogany block as a basis, two iron rods A, A, are 

 so planted as to extend perpendicularly, and of course parallel to 

 each other, about two feet in height. Upon these rods two iron bars 

 are supported horizontally, one, B, near their upper extremities, the 

 other at the height of about six inches from the wooden basis. In the 

 centre of the lower bar, there is a screw, D, having a handle below 

 the bar, and supporting above it a circular wooden block. Into a 

 hole in the upper iron bar, equidistant from the rods, is inserted a 

 hollow brass cylinder C, which at the lower end screws into an aper- 

 ture in a circular plate of brass, E, which is thus supported horizon- 

 tally a few inches below the bar. By these means room is allowed 



