270 



Prof. W. Beetz on the Development of 



London. Unfortunately I could not procure wire of any other 

 thickness than that of a moderate-sized knitting-needle, one 

 metre weighing 0*44 grm. When exposed to the action of the 

 current it was uncommonly quickly dissolved, so that I had to 

 construct a special voltameter in order to maintain the action for 

 a sufficient length of time. Two holes {a and b) were bored 

 through the under surface of a 

 glass vessel (see figure), and 

 closed with tight-fitting corks. 

 A round piece of caoutchouc was 

 firmly cemented on each of these 

 corks by means of gutta percha, 

 and on each of these india-rubber 

 plates was fastened a funnel- 

 shaped cap (c and d) . The wires 

 (e and f) were passed through 

 the corks and caoutchouc plates from below, so that the under 

 surface of the vessel remained water-tight. Over the two funnels 

 were eudiometers, held in their places by supports. A partition 

 of porous ware (g) divides the vessel into two cells. The posi- 

 tive wire is quickly dissolved, and to replace it as fast as used, 

 fresh wire is pushed up from below. Were it not surrounded 

 by the cap (c) it would be immediately eaten through at the point 

 projecting from the caoutchouc plate, where in fact the cur- 

 rent is most powerful. The piece thus separated is carried away 

 by the gas, and the experiment rendered useless for quantitative 

 purposes. If an experiment is to be interrupted without leav- 

 ing the wires exposed to the action of the electrolyte, they must 

 be withdrawn, the edges of the holes in the caoutchouc plates 

 closing the opening. 



The gas from the anode never ignited spontaneously ; in fact 

 the magnesium contained so small a trace of silicium that the 

 formation of siliciuretted hydrogen was not to be expected. Ana- 

 lysis of the gas showed it to consist of hydrogen alone. The 

 accompanying phenomena at the positive wire, and the relative 

 quantities of gas disengaged from the two poles, differed very 

 greatly according to the nature of the electrolytes used ; it was, 

 however, in these accompanying circumstances that the cause of 

 the anomalous development of hydrogen was found. 



For most of my experiments I employed a solution of sul- 

 phate of magnesium, because I thought by the use of this liquid 

 they would be least likely to be obscured by secondary action. 

 The action was very similar to that which Wohler and Buff 

 observed in the case of aluminium in a solution of its chloride ; 

 that is to say, the positive wire was simply dissolved. I always 

 noticed, however, that as soon as the wire was dipped in the 



