2690. I have repeated this experiment most anxiously and care- 
fully, but have never obtained the slightest trace of: action with 
the bismuth. I have obtained action with the iron; but in those 
cases the action was far less than if the iron were applied outside 
between the horseshoe magnet and the needle,: or to the needle ' 
alone, the magnets being entirely away. On using a garnet, or - 
| a weak magnetic substance of any kind, I cannot find that the 
arrangement is at all comparable for readiness of ‘indication or » 
delicacy, with the use of a common or an astatic needle, and 
Supposed Polarity of Diamagnetic Bodies. 203 
« 
polarity of bismuth when these fail to show it. Still I may have 
made some mistake; but neither by close reference to the de- « - 
es nor to the principles of polar action, can I discover 
wh 
2691. There is an experiment which Pliicker described to me ‘ cs 
and: Which at first seems to indicate strongly the polarity of bis-_ 
muth: If a bar of bismuth (or phosphorus) be suspended hori- : 
zontally between the poles of the electro-magnet, it will go to. cm 
the equatorial position with a certain force, passing, as I have said, > 
from stronger to weaker places of action (2267.), Ifa bar’ off 
iron of the same size be fixed in the equatorial position a little: 
below the plane in which the diamagnetic bar is moving, the lat-* | 
ter will proceed to the equatorial position with much greater force." 
than before, and this is considered as due to the circumstance es 
that, on the side where the iron has N polarity, the diamagnetic 
body has § polarity, and that on the other side the $ aes m5 
the iron and the N polarity of the bismuth also coincide. 
2692. It is however very evident that the lines of 1 
force have been altered sufficiently i in their intensity of dire 
“. 
fect. For, consider the b as just le 
going to the hs our positions at a “<a ment ae ‘an 
oe tear force from pole to pole of the electro-in 
awa bao the other hand, when it sie 
: extre are under ¢ am 
mnie e sanie 
hetic is.u a. cee 
-qply those sae The effect is lik a 
bly, the’ whole sidditia : 2 effect is like many others” ; * 
whieh I have referréd Setiensctyvallc action (2487-2497, ), ~ 
al Tesui 
and tars not, I think, sis Shad to the experiniental pr root. ote .Y 
giamacnetic ic polarity. : ‘ 4 
