320 Astronomical and Nautical Collections.. 
proved is, that magnetism may be developed in different bodies by 
the action of electricity ; but the identity of the fluids is not neces- 
sarily proved by the important facts, which have lately been dis- 
covered, relating to their connexion. Happily the decision of the 
question is not necessary for the purpose of this memoir, which is 
independent of the intimate. nature of the boreal and austral fluids ; 
its object being simply to determine the results of their attractions 
and repulsions, and the laws of their distribution in magnetized 
odies. 
On this point the opinions of natural philosophers have not al- 
ways been uniform. Before the time of Coulomb, the two fluids 
were supposed to be tranferred, by the act of magnetizing a needle, 
to its two ends, which thus became opposite poles; while in the 
opinion of this illustrious experimenter, the boreal and austral 
fluids are actually displaced in a very minute degree only, and do 
not even quit the particles of the body to which they originally be- 
longed before it was magnetized. This opinion, however singular 
at first sight, has yet of late years generally prevailed: but the 
theory depending on it could not be correctly developed without 
an elaborate analysis, as will appear in the sequel of this me- 
moir. 
The general fact by which this opinion is supported, and which 
indeed appears to establish its truth without any reasonable doubt, 
is this: if we bring a magnet near to a piece of soft iron, the iron 
will be magnetized by induction, and the two substances, when in 
contact, will adhere to each other more or less strongly. The same 
will happen to one or more pieces of iron brought near the first ; 
they will also be magnetized by induction, and will adhere to the 
first piece. If we then separate the different pieces, and remove 
them from the magnet, we shall find that they have all returned to 
their natural state, and that no portion of the magnetic fluid has 
passed either from the magnet into the iron, or from one piece of 
iron to another. “Now this is a marked difference between mag- 
netism and electricity in conducting bodies; for the electric fluid 
passes freely from one of these bodies to another when they are in 
contact, or even when they are sufficiently near for the electric 
