During the months of May and June of this session, we have endeavoured to investigate certain questions suggested by our experience of the discharge of electricity through the gases and through oil of turpentine.

Ordinary paraffin-oil, when used as a dielectric, exhibits the same phenomena as oil of turpentine. Gas is liberated by the passage of the spark, and at the same time carbon is deposited. Once produced, the gas bubbles make the passage of the spark more easy through bringing the electrified surfaces nearer to one another; hence, in taking a series of observations, it is necessary to get rid of the bubbles after the passage of each spark. They were attracted generally to the positive surface, but sometimes to the negative. The attraction was more marked when no jars were attached to the Holtz; it was not so powerful as in oil of turpentine, and was generally in the opposite direction.