De Luc*s Electric Column, 317 



tompanson with those of which we have had occasion to 

 give an accouui in former years. 



M. Guylon has made us acquainted with a new crystal- 

 line form of the diamond. We know that the forms under 

 which it is most frequently presented, are tlie regular octa- 

 hedron and the dodecahedron with rhomboidal faces. The 

 variety discovered by our associate is formed of two demi- 

 sphcroids, the returned position of which, imperfecilv ter- 

 minated at one of its extremities, pre^^ents at the other very 

 clear re- entering angles, which characterize the form called 

 hemitrope by M. Hauy. 



The same member, having directed his inquiries to the 

 tenacity of metals, was led to some new experiments on the 

 diminution of specific gravity in lead, in consequence of 

 being put into a vice, as proved by Musclienbroek ; and 

 the cause of which remained unknown. Pieces of this 

 metal were dr'.ven into ferules ; and when the dies and the 

 latter were adjusted, so that there could be no oozing out 

 of metal, nor was the lead permitted to become soft, the 

 lead in this case was found, like all the other metals, to in- 

 crease in specific gravity by the operation. 



M. Sage has communicated to the class his inquiries re- 

 specting emery, and the substances which are calculated to 

 supply its place in polishing. It results from his observa- 

 tions, that the pulverized chrysolite of volcanoes mav supply^ 

 the place of emerv. All the artists who employed it have 

 been satisfied with its effects. 



[To be continued.] 



LI I. Intelligence and Miscellaneous A?' tides, 



DE LUC*S ELECTRIC COLUMN, 



We learn, by a communication dated 23d April, that the 

 small bells which were connected to De Luc's electric co- 

 lumn^ mentioned in our last number, ceased to ring for 

 about a minute on the 24th March; and again on the same 

 day for about three minutes. They were also supposed to 

 have stopped for about half a minute the next day ; but this 

 is much doubted. Since that tnne they have been known 

 once to cease ringing. On the 15th April, the closet 

 where they are placed was opened, when he clapper was 

 observed to vibrate with very great velocity. It is thought 

 that the loudness of the sound is considerably inert ased 

 of late ; also that the vibrations of the clapper are quicker" 

 than when the apparatus was put into the closet on the 1 4th 

 MarcU. [April 28.] 



The 



