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XLT. 



ON A DIRECT READING ELECTROLYTIC AMPERE METER. 

 By J. JOLY, M.A., D.Sc, F.R.S. 



[Read May 18, 1892.] 



In the ordinary instruments for measuring current strength by 

 means of chemical actions, the element of time constitutes neces- 

 sarily one of the quantities observed. For the general method is 

 to estimate from the mass or volume 

 of the products of electrolysis the 

 number of culombs which have tra- 

 versed the circuit in an observed time, 

 and from these data to calculate the 

 mean current in amperes prevailing 

 in the interval. 



For many purposes this method 

 is inconvenient, and has essentially 

 remained a laboratory method, both 

 on account of the time necessarily 

 consumed in effecting a measurement, 

 as well as from the care and pains 

 necessary in order to obtain a correct 

 estimation of the mass or volume of 

 the liberated products of electrolysis. 

 The method, too, affords a fuean read- 

 ing only of the current over a certain 

 interval, and cannot follow and ex- 

 hibit brief variations of current 

 strength. 



The instrument described in this note 

 was devised by me several years ago in r 

 the hope of meeting those objections, ^ fo, .dj 

 Pressure of other work has, till the present, hindered me from trying 

 it. It consists (see fig.) of a spherical glass bulb, as made, about 



