TRANSACTIONS OF THE SECTIONS. 53 
rod will be in a condition to receive on the sides facing the positive coating, and 
of giving on the sides facing the negative coating; that the rod is neutral in the 
middle arises from the opposite and equal tendencies of the extremes. Now let the 
knobs approach to make the discharge. This is not effected by a continuous pas- 
sage of the fluid from one end to the other, since, at any break in the circuit, a card, 
being interposed, is pierced so as to have a bur on both sides, showing that the pas- 
sage was made in pulses; nor do these commence at either end and proceed to the 
other, for the one end cannot wait to receive or to give during the time of the pas- 
sage. The pulses must therefore commence simultaneously at both ends, and close 
about the middle, where, consequently, the spark would be last seen. Besides there 
is no reason whatever that the motion should begin at one end rather than the other ; 
and the same follows from this, that the one side of the discharging rod is positive, 
and the other equally negative, while it is neutral in the middle. 5 
Therefore, on the supposition of only one electric fluid, the spark ought to be seen 
precisely at the same time at the two extremities, and latest of all about the middle 
of the rod: also the explanation by one fluid presents fewer difficulties than by two 
fluids. The observations made were applied to the explanation of some other elec~ 
trical phenomena, as the residual charge, the charging of thin and thick glass, the 
star and brush, &c. 
‘On the Identity of the Existences or Forces of Light, Heat, Electricity, Mag- 
netism and Gravitation. By Joun GoopMAN. 
The author has already shown in a former communication that the substance 
potassium, which displays the highest chemical properties, possesses also the most 
exalted electrical powers. In order to show the further prominence of this metal 
in its calorific phenomena, he devised several experiments, and has succeeded in 
showing that potassium contains also the greatest known amount of caloric of any 
solid material body. 
When this metal was subjected to percussion or screw compression in a steel 
cylinder by means of an air-tight piston, also of steel, a flame of considerable dimen- 
sions was discovered to issue from a minute orifice—being given off from the interstices 
of the metal as water from a sponge—and this frequently accompanied by a loud ex- 
plosion. By enlarging the orifice the flame and explosion would gradually diminish, 
until large portions only of red-hot metal would exude during percussion. 
The explosion was found by experiment to be caused by the combustion of the 
finely-divided particles of heated metal which escaped, depriving the atmosphere of 
its oxygen and producing an instantaneous collapse of the surrounding air, as is 
represented to be the case immediately after the transition of lightning. 
The author attributes the escape of caloric through so small an orifice, and by the 
sides of the piston, instead of by radiation to the adjoining excellently conducting 
cylinder, to the intense attraction of caloric for potassium. 
The pure flame seen in these experiments was projected in vacuo as in oxygen, 
but with considerably diminished splendour, showing that it exists independently of 
combustion. 
The author ascribes to caloric attraction for other kinds of matter, and supposing 
that all bodies are naturally either minus or plus as regards their amount of caloric, 
and attract each other simply as in electrical phenomena, proposes to explain thus 
the force of gravitation and the attraction of cohesion. ? 
He points out the great precision with which the numbers given by philosophers 
to represent capacity correspond with the powers of electric affinity of the various 
metals, as exhibited in thermo- and mechanical electricity, and suggests that electrical 
affinity and “ capacity” are not improbably analogical. 
“ Potassium is thus found (says the author) to possess a vast amount of caloric 
and to exhibit calorific phenomena, of which no other solid substance in nature 
is known to be capable, and it is therefore not improbable that its extraordinary 
chemical and electrical powers are derived from the quantity of latent heat which it 
contains.” 
Employing the argument used in his former communication that chemical and 
electrical phenomena are one and the same thing, because the substance producing 
