ON THE ELECTRICAL PROPERTIES OF PURE SULPHUR. HI 
then numerous difficulties arise which are to be got over by electrostatic screening, 
avoidance of contact forces, insulation, &c. The following diagram shows our 
arrangements :— 
Fig. 2. 
EARTH I EARTH 
A, B, C, D, E, F (fig. 2), are the six points of a reversing key. The points B and C 
are insulated by supports of fused quartz. The condenser is inserted at S. GH is a 
pillar make-and-break key with mercury cups (see Plate 3, fig. 3). Between B and E 
is placed a wire of aluminium, so arranged that when the rocking key is thrown over 
from its charging position A B E D to its discharging position B C F E, this 
wire momentarily touches part of the rocker connected with B, the other end being 
permanently connected at E. In this way the discharge can be made to occupy a very 
short time, say - 01 sec., and includes the key. A short-circuiting key is sometimes 
also kept in C and F till the discharge has taken place. During the charging G and 
H are connected. 1IA is a long wire enabling the battery, &c., to be placed far 
enough away not to complicate matters by direct electrostatic induction. As soon as 
the rocker is moved over far enough to be insulated from A, this point is earthed and 
the rocker then moved over to CF, the short-circuiting key being removed after 
discharge has taken place, and, of course, before the rocker makes contact at C or F. 
At one time an additional key was used for the short circuiting of the electrometer, 
but it was given up as merely increasing the trouble of insulation. The electrometer 
was adjusted to a sensitiveness of about 40 scale divisions per Clark cell, and this 
did not vary by more than 2 divisions over the scale. Thermo-electric effects, &c., 
prevented the sulphur from ever giving absolutely no deflexion after the removal of 
the charge. About two hundred experiments were made on the sulphur and mica, 
and we know nothing whatever against the summary, which we consider to be a 
sufficient statement. 
