958 REPORT—1890. 
dynamo-generated continuous current passing at about 100 volts, in such a way 
that the current passes from hand to hand, and the total contact-area is about 
90 square centimétres :— 
‘1. A current of about 0°016 Ampére will pass through it. 
‘2. That this current can be borne without discomfort for fifteen to thirty 
seconds, 
‘3, That after about thirty seconds unpleasant burning sensations become 
marked, and quickly increase. 
‘4, That the subject is perfectly able to release himself at will during any 
portion of the time of contact. 
‘(6.) That when the human body comes into contact with dynamo-generated 
alternating currents alternating at about sixty to seventy per second, under the 
same conditions as above :— 
‘1. A current of about 0:025 Ampére will pass through it. 
‘2. That this current is six times greater than that which produces discom- 
fort. 
‘3. That instantly the subject is fixed by violent muscular contraction, and 
suffers great pain. 
‘4, That the subject is utterly unable to release himself, but remains exposed 
to the full rigour of the whole current that may be passing. 
‘(c.) That when circuit from electric-light or power conductors is accidentally 
completed through the human body, the danger of serious consequences is many 
times greater when alternating than when continuous currents are passing at equal 
voltage; and this is still, to a large extent, true if the voltage of the continuous 
current be double that of the alternating. 
‘(d.) That with both forms of current a reduction of contact-area materially 
reduces the amount of current-strength that passes. 
‘That with the alternating current, if the rate of alternation be reduced below 
fifty per second, the sensations of pain accompanying muscular fixation will be in- 
creased ; while, if the rate of alternation be increased, the pain will be diminished.’ 
4, On Electric Lighting and Fire Insurance Rules. 
By Witson HartNeELL. 
5. Secondary Cells. By W. J.S. Barper Srarkey. 
The author in this paper limited himself to a description of his own experiences 
in regard to secondary cells, primarily with a view to provoke discussion on the 
subject. 
Ss after the introduction of M. Faure’s cells his attention was drawn to the 
hard film of sulphate of lead formed on the plates which materially interfered with 
their efficiency, and, as a result of experiments, he ascertained that the addition of 
a small quantity of carbonate of soda to the dilute acid serves to remedy this evil, 
even when the cells are allowed to remain idle for a considerable time. Subse- 
quently, in the case of a small installation of twenty-two E.P.S., 350 Ampére-hour 
cells, the plates of which showed signs of sulphating, carbonate of soda (ordinary 
washing soda) wasadded in small quantities, and on proceeding with the charging 
the plates were restored to their original condition. The cells thus treated have 
since been in use for a period of five years, and are now in perfect condition. The — 
subsequent experiments on this subject by Mr. Preece were alluded to. 4 
The author advised that large cells be used for stationary work, and that they 
be both charged and discharged at low rates. Various details in regard to the © 
management of cells were discussed, the practice of packing the plates in a solid — 
though porous mass formed by mixing plaster of Paris and sawdust being specially 
recommended. = 
