318 



the greater energy of the small battery. In this the number of plates 

 being tenfold gives tenfold intensity, although the aggregate quantity 

 of surface in the whole battery is not -r'oth part of the acting sur- 

 faces in the large battery. 



The advantage of a large quantity of fluid is evinced by the long- 

 continued action of the small battery ; and it is also observed that in 

 very numerous combinations, a certain distance between the plates 

 becomes necessary to prevent spontaneous discharges, which the au- 

 thor found to take place in a battery of 1250 plates of four inches 

 square. 



With this battery of 1250, excited by a fluid of the same strength 

 as was used in the former experiments, the author ascertained the 

 striking distance through the air to be -jVth of an inch, care having 

 been taken to dry the air, through which the discharge took place, 

 before the experiment, as well as to avoid any increase of tempera- 

 ture previous to the discharge. 



The electric light was also made to pass through a vacuum, and 

 was observed to be the same as from a common electrical machine. 



The effect of this great number of plates on imperfect conductors, 

 was of course uncommonly powerful, but yet their power of fusion 

 was comparatively weak, as they barely melted half an inch of the 

 same platina wire that had been used in the former experiments ; 

 and hence it is evident that the construction must be different ac- 

 cording to the purpose for which the battery is designed. 



For igniting perfect conductors large plates are necessary, but they 

 need not be numerous ; and for overcoming the resistance of imperfect 

 conductors number is requisite, but the size of the plates may be 

 small. 



The new method of constructing the trough wholly of wood, 

 with moveable plates joined together only at top, is much preferred 

 to the old construction, as the plates are more easily cleaned or re- 

 paired, and as they expose double extent of surface. 



The Bakerian Lecture. An Account of some new analytical Researches 

 on the Nature of certain Bodies, particularly the Alkalies, Phos- 

 phorus, Sulphur, Carbonaceous Matter, and the Acids hitherto unde- 

 compounded ; with some general Observations on Chemical Theory. 

 By Humphry Davy, Esq. Sec. R.S. F.R.S. Ed. and M.R.I.A. 

 Read December 15, 1808. [_Phil Trans. 1809,^. 39.] 



The objects which principally occupied Mr. Davy's attention in 

 the present lecture are, the elements of ammonia; the nature of sul- 

 phur ; the nature of phosphorus ; tne states of the carbonaceous prin- 

 ciple in plumbago, charcoal, and diamond ; the analysis of boracic 

 acid ; the analysis of fluoric acid ; with a series of numerous experi- 

 ments on muriatic acid. 



With respect to ammonia, he has been induced to reconsider the 

 subject, not from any doubt which he himself entertained of the cor- 

 rectness of his former results, but on account of the opinion still 



