370 Scientific Intelligence. 



Wedgewood's basin, at a temperature of about 300° of Fahrenheit, until it 

 was so dry as not to dim a cold plate of glass held over it, Mr Faraday re- 

 marked, that when it was stirred with a platina spatula, it became in a few 

 moments so strongly electrical, that it could not be collected together, but 

 flew about the dish whenever it was moved from its sides into the sand- 

 bath. This tock place either in porcelain, glass, or metallic basins, and 

 with porcelain, glass, or metallic stirrers. When the particles were well 

 excited and shaken on the top of a gold leaf electrometer, the leaves di- 

 verged two or three inches. When cooled out of the contact of air, the 

 same phenomena took place. When excited in a silver capsule, and left 

 out of contact with the air, the powder continued electrical for a great 

 length of time, proving its very bad conducting power, in which it pro- 

 bably surpasses all other bodies. Mr Faraday remarks, that oxalate of 

 lime stands at the head of all substances, yet tried, as to its power of be- 

 coming positively electrical by heat. Quart. Journ. No. 38, p. 338. 



10. Electricity developed in Capillary Attraction. — M. Becquerel is said 

 to have demonstrated, that there is a sensible developement of electricity 

 during the ascent of liquids in capillary tubes. He first obtained this re- 

 sult by increasing the sensibility of Schweigger's galvanometer. He 

 placed three of these instruments together, so that the magnetic needle of 

 the middle one deviates from its ordinary direction, by the lateral effects 

 produced upon each of its poles by the contrary poles of the two other 

 needles. From this arrangement it follows, that, when an electric current 

 passes into the apparatus, tending to bring the needle into the plane of 

 the magnetic meridian, the middle needle will be as much less retarded 

 in its progress as the poles, opposite to its own, of the other two needles 

 are more remote from it, consequently, the oscillations will have a wider 

 extent than if there were only one galvanometer. 



In order to observe the electricity of capillary action, M. Becquerel 

 could not employ glass, as it is not a conductor of electricity ; but he em- 

 ployed sponge of platinum, and small pieces of charcoal. Pure hydro- 

 chloric acid, much diluted with water, is poured out into the platinum dish, 

 which communicates with one of the ends of the wire of the galvanome- 

 ter ; and into the dish is plunged sponge of platinum, which is fixed at 

 the other end of the wire. At this contact there is produced an electric 

 current, which goes from the sponge to the acid, and the direction of 

 which is contrary to that of the current which would have been obtained 

 if the acid had been attacked by the metal. As the interstices of the 

 sponge are filled with the fluid, the current diminishes, and it ceases when 

 the sponge has absorbed all the liquid which it can contain. Sometimes 

 the current takes another direction, but the cause of that is not known. 

 The same effect is produced with nitric acid, but it is less marked. The 

 same result was obtained with a small piece of charcoal, prevented from 

 touching the platinum by a band of papier Joseph. 



11. Electricity developed in Solutions and Mixtnres.— By means of the 



