104 
MESSRS. W. DE LA RUE AND H. W. MULLER ON THE 
Taking experiment I., which was made with rod batteries which had been just 
previously tested, we have the ratios 1, 2, and 3'33 as the charges of the 42'8 micro- 
farad condenser, with respectively 1080, 2160 and 3240 cells. We might, therefore, 
anticipate that the effects in deflagrating a wire would be as 1, 4, and 10. 
A direct experiment with platinum wire 0’0 125 inch diameter gave the following 
results, the charge with — 
Cells. 
1080 
heated 
Inches. 
1 
to the fusing point. 
2160 
deflagrated 
4 
heated 
5 
to the fusing point. 
3240 
deflagrated 
10 - 5 
melted 
11 
into globules. 
heated 
13 
to the fusing point. 
As occasionally we have accidentally been exposed to shocks, it appeared to us 
permissible, in self-protection, to ascertain whether life or health was in any way 
endangered by them ; we therefore made an experiment on a rabbit, with the con- 
denser of 42 8 microfarads charged with 2160 cells ; the discharge was passed from the 
inside of one ear to the throat, but produced no other effect than to paralyze the fore 
paws for about an hour ; it appeared, however, that but a very small portion of the 
charge had passed through the rabbit, inasmuch as afterwards, when the condenser was 
discharged, the report was nearly as loud as when the condenser is at full potential. 
Professor Stokes accidentally received the charge of this condenser, with 3240 cells, 
without injury (like the rabbit, he got only a small fraction of the charge), and one of 
us (De La Hue) has had a shock from the whole battery, without a condenser, of 
8040 cells; the shock was severe, and its numbing effects were felt for some hours; 
in every case the skin is pierced by a number of minute holes and cauterised where 
the charge enters. 
Experiments were made to test the portion of a charge that passed from a condenser 
when the opposite plates were connected by a certain length of platinum wire of a 
definite diameter. In order to measure the fall in potential of the condenser, one of 
its plates is placed in connexion with the cage (fig. 28), consisting of a glass shade 
lined with tinfoil, and having a hole in the top to permit of the insertion of a test 
plane, T, for taking a charge from the mushroom, M, in connexion with the other plate 
of the condenser, C. The shade rests on a glass disc, also coated with tinfoil, except 
at the centre, where a space 3 inches in diameter is left uncoated. For the suggestion 
of this arrangement, having for its object to insure that the test charge shall be always 
at the full potential, we are indebted to Professor Stokes. The cage is quite close to 
the quadrant electrometer, which we charge always to the potential of 2400 cells ; it 
is rendered much less sensitive than usual by the separation of the suspension threads. 
The test plane we use up to 3240 cells is a brass disc 2 inches in diameter.' 55 ' 
* Recently we have found it to be more convenient to use a quadrant electrometer furnished with an 
induction plate placed above one of the quadrants and adjustable in distance from it. — Dec. 13, 1877. 
