208 Miscellaneous Intelligence. 



powerfully as Iceland spar ; and he found them also to possess 

 similar relations to water. 



During his experiments on the electricity of minerals, M. 

 Haiiy found that the second apparatus also had the power of pre- 

 serving its electric state unimpaired for a long time ; a circum- 

 stance scarcely to be expected from its construction. In examin- 

 ing the apparatus this power was found to depend on the seal- 

 ing-wax foot ; for if that were removed and the needle hung by 

 silk, though it readily took electricity from other bodies yet it 

 also soon lost it ; whereas, on its pivot and foot of sealing-wax, 

 it retained it in damp weather for hours. This appears to de- 

 pend on a portion of electricity, which, when the needle is first 

 charged, passes on to the surface of the sealing-wax, and re- 

 maining there for awhile gradually returns to the needle, as its 

 state is reduced by the action of the moist air, and supports, as 

 it were, its electricity at a higher tension than it otherwise would 

 have. M. Haiiy expresses this by saying that the sealing-wax 

 has the power both of conducting and insulating ; by the first 

 it receives a part of the electricity given to the needle, by the 

 second it retains it, and then by the first it gives it back again 

 to the needle when the air has taken away its own portion. 

 The evident conclusion from the experiments are, that the ap- 

 paratus is always ready for use, and will act in any weather. — 

 Journal de Physique. P. 89, p. 455. 



11. Illumination by £/ec<rict>y.— Professor Meinecke of Halle 

 has, in Gilbert's Annals, 1819, No. 5, proposed to illuminate 

 halls, houses, and streets by the electric spark, and expresses 

 his strong persuasion that one day it will afford a more perfect 

 and less expensive light than gas-illumination, and ultimately 

 replace it. His plan is, to arrange, what are called in electricity 

 luminous tubies, glasses, ^c. ; i. e., insulating substances, having 

 a series of metallic spangles at small distances from each other, 

 along the place to be illuminated ; and then by a machine send 

 a current of electricity through them : sometimes also partially 

 exhausted glasses, as the luminous receiver, conductor, Sfc, are 



