PERHAPS the simplest way of measuring a current of moderate intensity when once the electro-chemical equivalent of silver is known, is to determine the quantity of metil thrown down by the current in a given time in a silver voltameter. According to Kohlrausch the electro-chemical equivalent of silver is in C.G.S. measure 1.136 × 10-2, and according to Mascart, 1.124 × 10-2. Experiments conducted in the Cavendish Laboratory during the past year by a method of current weighing described in the British Association Report for 1882 have led to a lower number, viz. 1.119 × 10-2. At the rate the silver deposited per ampere per hour is 4.028 grams, and the method of measurement founded upon this number may be used with good effect when the strength of the current ranges from 1/20 ampere to perhaps 4 amperes. It requires, however, a pretty good balance, and some experience in chemical manipulation.