[ 3" ] 



[EXPERIMENTS ON] RESISTANCE TO 

 ELECTRICITY [1776] 



From MS. N. 19. See Table of Contents at the beginning of this volume. 

 See also near the end of the Introduction.} 



616] Comparison of conducting power of salt and fresh water in the latter 

 end of March and beginning of April, 1776. 



Tried with Nairne's last battery, 6 jars being chose, each of which held 

 very nearly the same quantity of electricity; the wires run into the bent ends 

 of the tubes being made to communicate with the outside of the battery, and 

 the wires run into the straight ends being fastened to separate pieces of tinfoil. 



The six jars were all charged by the same conductor: the communication 

 with that and each other was then taken away, and the jars discharged through 

 the tubes, one after the other, by touching the above-mentioned bit of tinfoil 

 by metal held in one hand, and the wire of the jar by metal held in the other 

 hand, the shock being received alternately through each tube. 



617] Exp. i. 



Distance of wires 

 In tube 15 t4 



6-5 inc. 

 5-8 

 3'5 

 4-2 



5'3 



40-7 



Sat. sol. S.S.* in tube .14, 

 salt in 69 of water in tube 15 



in short 

 tube than 

 in long 

 one 



very sensibly less 

 sensibly less 

 sensibly greater 

 scarce sensibly 

 just sensibly less 



Straw electrom. = 4. Th. = 57. [Resistance = 390000 Ohms, f] 

 Resistance of 4-7 inches in tube 15 supposed equal to 40-7 in 14. Therefore 

 sat. sol. conducts 8-6 times better than salt in 69 of water. 



Exp. 2. The same solution tried in tubes 22 and 23. 



Tube 23 22 electrom. at i \. Th. = 58. [R. = 118000] f. 



3'3 

 5'5 



sensibly greater. 



less in same proportion. 



4-4 inches in tube 23 = 41 in tube 22. 

 Therefore sat. sol. conducts 8-94 times better than salt in 69 of water. 



* [Saturated solution of sea salt.] 



f [The resistance of the saturated solution in Ohms, calculated from the measure- 

 ments in Art. 635 by Kohlrausch's data, is given for each tube within brackets to 

 indicate the absolute value of the resistances compared.] 



