608 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



found the pieces of charcoal covered with a white substance, so 

 inflammable that every piece that was taken out and left to drj, 

 took fire as soon as it became dry. I suppose that this combina- 

 tion contains two parts of phosphorous to one of carbon, or that 

 it is a biphosphide of carbon. I communicate this to the Associ- 

 ation as a new and interesting substance, and I leave to others 

 the application of it. The inside of the tube was covered with a 

 red substance, similar to amorphous phosphorous, which also took 

 fire as soon as it was dry. 



At the suggestion of the Chairman, 



Dr. Vanderweyde promised to repeat his experiment and pre- 

 pare an essay upon the new compound, to be offered for a 

 premium, 

 j^ Referred to the Chemical Section. 



NEW ELECTRIC MACHINE. 



Dr. Vanderweyde also offered a new electric machine made 

 entirely from India rubber. 



The common electric machines, said he, collects electricity at 

 the most unfavorable place, namely, at the ends of the conduc- 

 tors. This is like attempting to fill a reservoir by pressing the 

 water up from below. We ought to collect the electricity at the 

 centre of the conductor. Instead of the long conductor of the 

 usual shape, I made a slit in the conductor through which I 

 passed a long piece of vulcanized India rubber, and thus 

 obtained a much longer spark. I obtained a still longer spark 

 by conducting rings, to the center of which I attached the vul- 

 canized rubber. With my present machine I have four rings, 

 and obtain positive and negative electricity at the same opera- 

 tion. The rings are isolated by pieces of rubber, and are hollow 

 and filled with wafer, so that no electricity can flow out. I draw 

 the spark from a little brass knob, and I have obtained a spark 

 ten or twelve inches long. The India rubber produces resinous 

 electricity. If the friction is produced by some other substance 

 we may have a positive electricity. So that with two different 

 coverings, where the friction is produced, we may have either 

 positive or negative electricity. 



The Chairman. — Any known electric, except sulphur, may bo 

 electrified either positively or negatively. 



Referred to the Chemical Section. 



