48 SIXTH REPORT. — 183G. 



but contact with the zinc j)late of the other pair, but that the insulation 

 of each separate pair of plates was of still greater efficacy. He put 

 together 1200 pairs of zinc and copper cylinders on this plan, filled 

 with water alone, and found the effects as follow : the average size of 

 the cylinder being about equal to a four-inch plate, four pairs com- 

 municate a charge to an electrical battery sufficient to cause iron wire 

 barely to scintillate, and w-ill just decompose water ; 100 pairs cause 

 the gold leaves of an electrometer to diverge i of an inch ; 200 pairs 

 open the same § of an inch; 300 pairs cause the same to strike their 

 sides, and fire gunpowder placed loosely on a brass plate, the opposite 

 poles being connected with an electrical battery ; 500 pairs give a smart 

 shock, fire gunpov^der readily, give a visible stream of fire to the dry 

 fingers, and cauterize the skin as though with a red-hot wire ; 1 200 pairs 

 being connected with an electrical battery fuze the point of a penknife, 

 deflagrate brilliantly metallic leaves, tin-foil, and even stout silver 

 sheeting, &c., &c. Mr. Crosse has used a battery of this kind for 

 eighteen months without any sensible diminution of power. These bat- 

 teries are well calculated for electrical crystallization, and from ten to 

 fifty pairs of insulated cylinders Mr. Crosse thinks would answer every 

 purpose of that sort. 



Another subject noticed by Mr. Crosse was atmospheric electricity ; 

 he has for many years paid considerable attention to this part of the 

 science, and taken great pains in extending on loft)^ poles and insulating 

 with all possible care a copper wire ^j of an inch diameter and 300 

 feet long. The experiments made with this resemble in general those 

 made on a smaller scale by other experimenters. Mr. Crosse considers 

 a thunder cloud to be divided into zones of alternate positive and nega- 

 tive electricity. It appears to him that a nucleus is first formed of one 

 electricity, then a layer or zone of the opposite, and so on weaker and 

 weaker to the circumference. There are occasionally electric fogs nearly 

 as powerful as a small thunder cloud. Mr. Crosse has known during five 

 hours a stream of alternate positive and negative electricity pour from the 

 atmospherical conductor during a fog, and driving rain sufficient to fuze 

 a considerable length of strong wire. These electrical fogs appear to be 

 composed of alternate positive and negative columns. 



Remarks on the Results of some Experiments on the Phosphate and Pyro- 

 phosphate of Soda. By Henry Hough Watson. 



Mr. Watson's attention having been drawn to the discordant state- 

 ments given by different authors of the proportions of acid and base in 

 the salt called phosphate of soda, viz., in the dry state, he "was induced 

 to investigate the subject by experiment. On putting to the test the 

 experiment which Dr. Thomson gives, page 199, vol. i. First Prin- 

 ciples of Chemistry, of mixing a solution of 7 '5 grains of anhydrous 

 phosphate of soda with one of 20*75 grains of crystals of nitrate of lead, 

 the result was not an entire decomposition of each salt, but a little of 

 the nitrate of lead remained undecomposed. 



