TRANSACTIONS OF SECTION B. 473 
From these last-mentioned results one is led to believe that molecules of colour- 
ing matter distributed throughout the solid medium of the jelly aid in the spread- 
ing or diffusion throughout its mass of colouring matter similar to itself, and that 
the curved and straight lines of blue colouring matter are directly due to the 
influence of the metallic iron on the molecules of prussian blue around it. 
In another experiment, made with a view of observing the action of the magnet- 
ism of the earth on the phenomena observed in the experiments first mentioned, two 
slips of iron, A, B, similar to those used in 
the first experiment, were placed at right 
angles to and about an inch from each 
other. One was placed in a line with, and 
the other would of course be at right 
angles to, the magnetic meridian. The re- 
sults produced were quite unexpected. Each 
slip of iron appeared to assume a polarity ; 
the colour of the jelly became bleached in 
a cirele round one-half of each slip of iron, 
and the colour so removed appeared to be deposited so as to form a thick coating 
on the other half of each slip, and after many months lines of colour extended 
from the centre of each slip of iron, forming a series of circular lines round the 
bleached area. 
Experiments were made with slips of iron and copper, with iron and zinc, 
and with zinc and copper placed at a distance from each other, and the results 
showed that the one had a very marked action upon the other, although they were 
not in metallic contact. With zinc and copper bubbles of gas were developed 
from the zinc at the edge nearest to the copper slip, the bubbles forcing their 
way through the thick jelly from the centre of the edge of the zinc plate in nearly 
straight lines towards the copper, whilst the bubbles developed at other parts of 
the same edge of the zinc plate forced their way through the thick jelly in straight 
lines which, if prolonged, would all have met about the centre of the edge of the 
copper plate facing the zinc one. Gas was also simultaneously developed at the 
edge of the copper plate opposite the zinc one. From the copper, however, the 
gas did not develope in lines, but in a circular form beginning from the centre of 
the copper slip and gradually extending outwards towards the zine. 
Other experiments with slips of copper and iron, similarly placed at a distance 
from each other of about an inch, also showed a marked action upon each other by 
the lines of prussian blue molecules which flowed from them. ‘These lines flowed 
from the one metal to the other. They did not, however, go by what one would 
take to be the directions of least resistance, but flowing away from the opposite 
metals they swept round the outside, and then turned inwards as if the lines from 
the two metals would join; but the glass plates not being large enough, they 
stopped at the margin of the coloured jelly. One curious result observed in those 
lines was the formation of eddies; one line of colour developed from the metal 
going, for instance, in the opposite direction to the hands of a clock, suddenly ended 
in an eddy, whilst another line flowing from the eddy formed part of a circle going 
in the opposite direction. 
A number of experiments were made by placing discs of the same thin iron 
‘0075 inch thick x ‘67 inch diameter on paper coloured with prussian blue lying 
on the top of wet blotting-paper, the whole being enclosed between two plates 
of glass and immersed in pure water. The blue colour on the paper gradually 
became bleached in a remarkable manner; the bleaching seemed to take place round 
the iron in an elliptical form, the iron disc being, roughly speaking, in the position 
of one of the foci of the ellipse, and ultimately the whole of the paper became 
bleached. In two experiments after bleaching the author removed the top glass. In 
the first there formed, immediately the air touched the surface of the bleached paper, 
a deep blue spot about half a diameter from the disc, and the whole of the paper 
then gradually became of a slate blue colour. In the second an irregularly round 
deep blue spot made its appearance the instant the top glass was removed, and 
the paper then gradually became blue. Thus it would appear as if the discs of 
