ELECTRICAL PROPERTIES OF PURIFIED SULPHUR. 247 
To obtain the insoluble half the mould was prepared just as 
before, the sulphur melted as in the previous case, but the 
temperature was raised till the sulphur became thick and dark. 
It was then suddenly quenched in water, left in the mould for 
about half an hour till it became stiff enough for removal, and 
taken off with a sharp knife. 
The two halves of the needle were cemented together with 
sulphur by means of a piece of hot aluminium. A fine fused 
quartz-rod was fastened to the centre; to this was attached a 
mirror, and the upper end was bent into the form of a hook. 
This could be hung on to a glass hook suspended bifilarly above 
the quadrants with silk, so that the needle could easily and 
quickly be removed and replaced. 
To make the sulphur quadrants a shallow zinc dish was pre- 
pared, with a round hole at the centre, through which the wire 
from the needle was allowed to pass. Four zinc partitions were 
fitted in, dividing the dish into quadrants. The dish was heated 
and two opposite quadrants filled with sulphur, the temperature 
was raised till the sulphur was on the point of burning, when the 
whole was cooled by plunging into water or laying the dish upon a 
block of ice. ‘fhe partitions were removed, and the other quad- 
rants were filled with soluble sulphur. This sulphur was first 
annealed and then heated to the melting point, care being taken 
not to heat it much above 128° CO, 
The sulphur had to be freed from any free electrification due to 
rubbing, or any cause other than contact difference of potential. 
This was done by passing a flame over it several times. It was rather 
difficult to do this with the needles without cracking them or 
setting them on fire, so that no very complete series of results 
could be obtained with the same needle. 
The needle was first diselectrified and hung inside the quad- 
rants. Upon connecting one (adjacent) pair with the case 
and earth and bringing the other pair to a positive poten- 
tial of about 50 volts by means of a storage battery there was a 
deflection of the soluble end towards the charged pair of quad- 
rants. When the electrification was transferred to the dther 
pair of quadrants the deflection was reversed, that is to say, the 
soluble end was still attracted towards the charged pair. 
The deflection obtained in this way was very small, not more 
than two or three divisions on the scale, placed 1 metre away. 
To increase the deflection an electrophorus was used ; the results 
were exactly similar but much larger. The needle was hung 
above the quadrants, but the effects were not altered. In making 
further alterations the needle broke. 
The experiment was repeated with a new needle, but this time 
exactly opposite results were obtained. The soluble end being 
deflected towards the uncharged pair of quadrants. The effect 
