426 Prof. R. Bunsen's Spectral- Analytical Researches. 



zinc, it is necessary that a form be given to the chromic battery 

 such as shall render possible the removal of the plates from the 

 liquid each time the current is broken. Especial interest attaches 

 itself to a comparison of the consumption of zinc during current- 

 production with that which takes place in the unconnected bat- 

 tery, not only from a practical but also from a theoretical point 

 of view, inasmuch as theory alone affords no basis for deciding 

 the question whether zinc dissolved in the unconnected is partly, 

 wholly, or not at all used for current-production in the connected 

 battery. 



In order to decide this question, two exactly similar elements 

 — one connected and having a tangent-galvanometer in the cir- 

 cuit, the other unconnected — were immersed to an equal depth 

 in the same chromic liquid ; the quantities of zinc dissolved in 

 each case were then estimated at equal time-inter vals, while the 

 current-intensity of the connected elements was determined every 

 fifteen minutes. The results of these experiments are contained 

 in the following Table, where column I. contains the times of 

 observation in hours (t), column II. the corresponding current- 

 intensities J in B.A. measurement, column III. the zinc-con- 

 sumption V in the unconnected element, column IV. the con- 

 sumption of zinc, V e , theoretically required for the current-pro- 

 duction — calculated from the electrochemical equivalent of zinc 

 (0-03402), — column V. the actual consumption of zinc V^. (ex- 

 pressed in grammes) in the connected element. 



I. 



II. 



III. 



IV. 



V. 



VI. 



t 



J. 



V 



v e . 



v*. 





1 



56-0 



3-000 



6-860 



9-268 



260 



2 



54-5 



5-730 



13-536 



18-069 



25- 1 



3 



525 



8-381 



13-967 



26102 



23-5 



4 



50-7 



10-913 



26177 



24-623 



24-4 



5 



48-5 



13165 



32117 



42-033 



23-6 



6 



44-5 



15-326 



37-568 



48-336 



22-3 



7 



410 



17-468 



42-591 



54-434 



21-8 



8 



380 



19-305 



47-237 



60-531 



220 



9 



35 



20-966 



51-524 



65-481 



21-3 



10 



32-7 



22-508 



55-529 



70646 



214 



11 



30-6 



23-821 



59-277 



75-646 



21-6 



12 



28-3 



25095 



62743 



79-926 



21-5 



13 



26-4 



26-347 



65-976 



84-328 



21-8 



14 



24-7 



27-569 



69001 



87-946 



21-6 



15 



23-0 



28-779 



71-8L8 



91-827 



21-8 



16 



210 



30021 



74-390 



94-973 



217 



17 



190 



31-221 



76-718 



97-709 



21-5 



18 



180 



32461 



78 923 



100-520 



21-5 



From columns III. and IV. it is evident that, under the con- 

 ditions of the experiments, rather less than half of the quantity 



