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62 Prof. J. Nicklés on Magnetic Phantoms. 
Art. VIII.—On Fixing Magnetic Phantoms ; by Prof. J. 
NICKLEs. 
THE name phantom was given by M. de Haldat* to the fig: © 
ures which are obtained when iron filings are thrown upon 4 
sheet of paper or a pane of glass placed over a magnet. This 
physicist fixed these images by producing them upon a sheet of 
a coated with starch or prepared with gelatine. 
his process certainly enables us to obtain the general form 
of the phantoms, but all physicists can see that it suppresses the 
etails. I was more particularly struck with this fact on a recent 
occasion, where I sought to fix the phantoms of some new elec- 
tro-magnetic combinations; I therefore propose another method, 
which is here briefly given; it is very simple and succeeds 
perfectly. The paper upon which the phantoms are to be 
fixed is “waxed” paper. A sheet of this is placed over the 
filings had, while they were free to obey the action of the magnet. 
A condition indispensable to success, is, that the stratum © 
wax has a sensible thickness, so that it may suffice for the ag- 
glomerations, since these absorb melted fatty matter, even to — 
saturation. at this force of absorption is very energetically — 
r 
exercised, may be perceived after the cooling, since the pa 
about the agglomerations is deprived of wax, and differs thus in _ 
appearance from those parts where capillarity has not been exer _ 
cised, It is therefore possible to preserve to the phantoms the 
* Memoir before the Academy of Stanislas, p. 43, for the year 18389—1840. 
