700 Chronicles of Science. | Oct., 
until the water is projected into the air with an explosion, the vessel 
being frequently broken. It is to occurrences of this kind that boiler- 
explosions are supposed to be most frequently due, and it is the general 
opinion that if the water could be kept supplied with air, ebullition 
would take place with perfect regularity. The difficulty has been 
how to effect this necessary aération, and M. Dufour now proposes to 
accomplish it by carrying an insulated platinum-wire into the water, 
and connecting the wire and the boiler with the opposite poles of a 
battery. It is imagined that the decomposition of the water will keep 
it well supplied with gaseous material, and will prevent the ebullition 
from becoming explosive. 
An ingenious modification of the ordinary electrophorus has been 
devised by Messrs. Cornelius and Baker, of the Franklin Institute, for 
lighting gas. It consists of a spherical cup of brass lined with sheep- 
skin and silk, into which drops a corresponding hemisphere of hard 
india-rubber. The brass cup communicates with a wire near the jet. 
To light the gas, the hard-rubber hemisphere is raised by means of a 
little handle, and the spark passes, lighting the gas in its passage. They 
have also devised a portable electrophorus of tubular construction ; it 
consists of two brass tubes, united together by a ring of hard india- 
rubber, closed at each end, and covered internally with a silk padding. 
Inside the tubes is a cylinder of hard rubber, which passes freely down 
the tubes when they are reversed. The apparatus is grasped by the 
non-conducting ring and held upright, the hard-rubber cylinder being 
at the lower end. Upon reversal it passes to the other end, charging 
the brass tube in its passage. 
Father Secchi advises the use of fine sand or of powdered sulphur 
in the porous cell of the Daniel’s battery, in order to increase its 
constancy. He accounts for its action by supposing that when the 
ordinary liquid alone is used, there is greater liability to local action 
taking place upon the zine. In a battery, the circuit of which is closed 
for two minutes every quarter of an hour, the learned father has used 
an ordinary piece of commercial sheet-zine half-a-millimetre in thick- 
ness, which has continued in action for more than six months without 
showing the least sign of local corrosion. 
Our enterprising French neighbours, always before us in luxurious 
applications of science, are rapidly applying the electric light to the 
illumination of private and public assemblies. It has for some time 
past been introduced at the Tuileries on the nights of the grand balls, 
and the Abbé Moigno has lately made use of it during his lectures on 
the progress of science in the hall of the Société d’ Encouragement. 
Instead of being illuminated by the innumerable jets of gas with which 
the hall is provided, a single electric light placed in a central position 
lit the room in the most perfect manner. The consequence was that, 
although the lecture was delivered during the height of the hot season 
in Paris, the room was kept comparatively cool. 
The celebrated electrical instrument maker, Rhumkorff, has de- 
servedly been presented with the Napoleon III. prize of 50,000 franes 
for the induction apparatus that bears his name. The King of Hanover 
has also sent him a large gold medal. 
