78 Intelligence and Miscellaneous Articles, 



researches the condenser was always charged for the same time, 

 and discharged during- the same fraction of a second ; but the dis- 

 charge Mas separated from the charge by longer or shorter intervals. 

 This kind of observation appeared to me very suitable for putting 

 in evidence the true origin of the residual charge. 



I shall cite the results of a series of experiments in which the 

 duration of the charge was limited, like that of the discharge, to a 

 fraction of a second ; the dielectric was a disk of shellac 6 millims. 

 in thickness. 



1 . The condenser was charged and gauged immediately after : 

 the total charge was 45. 



2. The condenser, after being charged, was left to itself for 15 

 minutes, and gauged at the end of this time : the total charge was 

 again 45. 



3. The condenser was discharged immediately after being charged : 

 the residual charge was zero. 



4. Lastly, the condenser was discharged 15 minutes after the 

 charge: the residual charge was 27. 



Experiments 1 and 2 prove clearly that in the interval of 15 

 minutes the armature gauged loses nothing of its charge, and that 

 therefore no appreciable absorption is exerted by the shellac ; and 

 yet it follows, from experiments 3 and 4, that in this time of 15 

 minutes the residual charge rose from zero to 27. This increase of 

 residual charge can only depend on a different arrangement of elec- 

 tricity in the interior of the dielectric. When the charge has only 

 been maintained for an instant, the parts of the dielectric which 

 possess a great conductibility alone participate in the transmission 

 of the influence; and as an instant is sufficient to polarize them, 

 an instant is sufficient to restore them to the neutral state. If, on 

 the contrary, the apparatus has been charged for a sufficiently long 

 time, the elements endowed with a feeble conductibility come into 

 play ; and as they cannot be restored to the neutral state in a very 

 short time, they retain after the discharge almost all the electricity 

 they had before. This electricity retains a portion of the electricity 

 of opposite kind which is accumulated on the armature. 



The residual charge is thus seen not to depend on a property of 

 absorption specially belonging to insulating bodies ; it depends 

 simply on electrical movements which take place in the interior of 

 these bodies in virtue of their conductibility. — Comptes Rendus, 

 May 2, 1864. 



ON THE BOILING OF WATER, AND ON THE EXPLOSION OF STEAM- 

 BOILERS. BY M. L. DUFOUR OF LAUSANNE. 



In the experiments which I have had the honour of communi- 

 cating to the Academy, I have shown that the boiling-point of 

 water and of other liquids may experience considerable retardation 

 when these liquids are heated in the body of another liquid of the 

 same density and without touching the sides of the vessels. In this 

 mode of heating the liquids, it cannot be said that their boiling is 



