Scientific Intelligence. — Natural Philosophy. 189 



rior of a bell heated to 25°, is attracted by a stick of gum lac, 

 the moment it begins to cool. The attraction continues so long 

 as the cooling lasts. If the small cylinder has been raised to 

 30°, it will acquire, during refrigeration, besides the property of 

 attracting, two electrical poles^ which disappear when the tem- 

 perature rises. At 100° and 150°, the phenomena are the same. 

 Thus, under the influence of an electrified body, a small glass 

 cylinder acquires, at the moment of cooling, two electrical poles, 

 which vanish rapidly when the temperature is raised. These 

 effects are analogous to those which tourmaline presents in the 

 same circumstances, with this difference, that the development 

 of electricity in the latter is produced by circumstances of crys- 

 tallisation. Whence it may be concluded, that, in the expan- 

 sion of bodies, there is an absorption of electricity, and probably 

 an emission during contraction. M. Ampere's ingenious theory 

 regarding the electrical nature of atoms, accounts in a satisfac- 

 tory manner for these important facts. M. Becquerel then gave 

 an account of the new researches which he has made with re- 

 spect to tourmalines, from which there results, that these mine- 

 rals, when of a certain length, are not electrified by any of the 

 means of exciting that power with the assistance of heat ; that, 

 in proportion as they diminish in size, they become more elec- 

 trical ; and that, admitting this law to continue to the smallest 

 particles of bodies, these must assume a considerable electrical 

 intensity on the application of weak variations of temperature. 

 The facts contained in this memoir appear to have thrown much 

 light upon the electrical state of atoms. M. Becquerel is of opi- 

 nion, that they are capable of leading to accurate ideas respect- 

 ing the cause of the great phenomena of nature. All kinds of 

 glass are not adapted for the experiment. Those which are 

 highly alkaline (and almost all that are made at present are of 

 this kind) are too bad conductors to allow the phenomena, an- 

 nounced by M. Becquerel, to be observed. That learned gen- 

 tleman owed the discovery of the remarkable facts which he 

 made known to a fortunate chance, which led him to make use 

 of glasses manufactured fifty years ago. When he used glass 

 of the present day, all the phenomena disappeared. He soon 

 discovered that this was owing to the great quantity of soda em- 

 ployed in the manufacture of glass at present. 



