1840.] The Galvanic Battery 1161 



battery, and other two at the extremities to which the platinum igniting 

 wire was attached. With these nine junctions, five cells of a battery 

 14 by i caused saltpetre cloth to ignite, but four cells w^ere not able 

 to effect this. New junctions were made at the termination of each 

 experiment, till from nine they extended to twenty-four, and still the 

 same strength of battery sufficed to insure the ignition. The junc- 

 tions were carefully made, and the contact rendered as perfect as 

 possible. 



When the distance from which a charge is to be fired is increased, 

 either the strength of the battery, or the diameter of the wires 

 employed, must be increased also. The exact proportion existing 

 between these increments has not yet been decided, and the results of 

 experience, as far as it has extended, must on this point guide our 

 proceedings. Colonel Pasley states that with a battery of 10 cylinders, 

 21 inches high and 3 J inches in diameter, having zinc rods 21 inches 

 long and one inch in diameter, he invariably succeeded in igniting 

 charges at 500 feet distance with copper wires l-5th of an inch in diame- 

 ter. The following experiments were made in Fort William with a bat- 

 tery of the rectangular form, consisting of 12 cells, each 14 irches square 

 on the sides, having edge and bottom pieces 14" by i." The zinc 

 plates were new and unamalgamated, the pasteboard cases in good 

 order. The solution of sulphate of copper in the proportion of 1 

 of salt to 3 of water, the sulphate of soda 1 salt to 8 water. The 

 quantity of the former in each cell was 2^ lbs. by measure, of the latter 

 f lb., and the battery was found to be in excellent action a iew minutes 

 after the solutions were poured in. The igniting effect was as- 

 certained by bringing a small piece of platinum wire, forming part of 

 the circuit, in contact first with dry cloth saturated with saltpetre, and 

 afterwards with fine dry Dartford powder. 



Experiment 1. The length of the circuit in this experiment was 

 300 feet, each conductor being 105 feet long, and composed of three 

 strands of copper wire, each l-20th of an inch in thickness, twisted 

 like a rope. With four cells immediate ignition of saltpetre cloth 

 was effected, but with three cells it was not till after some time, that 

 the same effect was produced. With four cells the powder ignited 

 readily, but I found it impossible to effect ignition with only three 

 cells. 



