II. ELECTRICAL RHEOMETRY. 57 



APPENDIX. 



A Series of Experiments showing the relative strength and constancy of the several 

 kinds of Voltaic Combinations for obtaining Electric Currents. 



These experiments require very little explanation, except in a few cases. Grove's, 

 Bunsen's, and Daniell's battery had all the same dimensions, when nothing is 

 marked; they were charged in the usual way. The height of cylinders was 

 12°™""-, the diameter of the larger receiver 8'^™'™-, which was cylindrical. 



Series C was made with a copper case 22'*°'™- high and long, and 3 broad. The 

 sulphuric acid was diluted with five times its weight of water, and the solution of 

 common salt was always saturated. 



Wheatstone's combination consists of amalgam of zinc in an earthen cell, with 

 copper outside, in a solution of sulphate of coj^per. 



Bagration's is a plate of zinc in a case of copper, with clay watered with a solu- 

 tion of ammoniacal salt. After the first day, this preserved 6° for four months 

 continually. 



Each battery was left untouched from the beginning to the end of the experi- 

 ment, if not noticed otherwise. 



We mean by inverted battery when the + element is larger than the — one. 

 The rheometer used was that described § iS. See note ('), page 55. 



15 



