Page:Proceedings of the Royal Society of London Vol 1.djvu/338

Rh 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 goth part of the acting sur- faces in the large battery.

The advantage of a large quantity of ﬂuid is evinced by the long- continued art-ion 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 author 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 315th 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 temperature 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 objects which principally occupied Mr. Davy’s attention in the present lecture are, the elements of ammonia; the nature of sulphur; the nature of phosphorus; the states of the carbonaceous principle in plumbago, charcoal, and diamond; the analysis of botanic acid; the analysis of ﬂuoric acid; with a series of numerous experiments 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 correctness of his former results. but on account of the opinion still