496 Mr, Babbage md Mr. Herschel's account, &c. 
power of the substance, which is out of question in the indi- 
rect mode of action here considered. In fact, if the retentive 
power of the solder were reduced to nothing, i. e. if it gained 
and lost magnetism instantaneously, it would still act as a 
conductor, and probably the better for this quality ; so that 
the communication between opposite sides of a slit, or conti- 
guous portions of two adjacent particles of a powder, would 
still be kept up by it, provided it were susceptible of mag- 
netism at all. The observed and very striking fact then of 
the powerful action of bismuth as a conductor, while its ac- 
tion as a magnet is so extremely feeble, is in itself a strong 
argument for the independence of these two qualities, which 
we have designated by the expressions^susceptibility, and 
retentive power, and may possibly be made the foundation of 
a mode of distinguishing and measuring their degrees in 
different substances, 
C, B, 
J, F. W, H, 
