52 I'HILOSOPHXCAL TRANSACTIONS. [aNNO IJQl. 



on these acids which may from analogy be supposed to contain vital air, but 

 which are not affected by the application of charcoal. With this intention he 

 made phosphorus pass through a compound of marine acid and calcareous earth, 

 and also of fluor acid and calcareous earth, but without producing in either of 

 them any alteration. Since the strong attraction which these acids have for cal- 

 careous earth tends to prevent their decomposition, it might be thought that in 

 this manner they were not niore disposed to part with vital air than by the at- 

 traction of charcoal. But this however does not appear to be the fact. He has 

 found, that phosphorus cannot be obtained by passing marine acid through a 

 compound of bones and charcoal, when red-hot. The attraction therefore of 

 phosphorus and lime for vital air, exceeds the attraction of charcoal, by a greater 

 force than that arising from the attraction of marine acid for lime. 



XII. A Meteorological Journal, principally relating to Atmospheric Electricity; 



kept at Knightsbridge, from the Qth of May, lySQ, to the 8th of May, I79O. 



By Mr. John Read. p. 185. 



A description of the instrument for collecting atmospheric electricity, used in 

 the following journal, is as follows. 



Fig. A, pi. 1, represents the apparatus, aa is a round deal rod, 20 feet long, 

 2 inches diameter at the lower, and 1 inch at the upper end. Into the lower end 

 of it is cemented a solid glass pillar b, 22 inches long; the lower end of the glass 

 stands in a hole made for it in a pedestal of wood c, which slips on the fore-part 

 of an iron bracket d, driven into the wall, and supports the whole. About 13 

 feet above the bracket d, is fixed to the wall a strong arm of wood e, which 

 holds perpendicularly a strong glass tube f, through which tlie rod is slid gently 

 upwards, till the glass pillar b may be lowered into the hole made for it in c. It 

 is thus fixed, and stands 1 2 inches from the wall. The tube p is of sufficient 

 width to admit a case of cork, fastened in the inside of it, at the part where the 

 tube is sustained by the arm of wood e, so that the rod, when bent by the wind, 

 cannot touch the tube or break it. The upper extremity of the rod is termina- 

 ted by several sharp-pointed wires g. Two of them are of copper, each J- of an 

 inch thick; and, in order to stiffen the rod, as well as conduct more readily the 

 dectric fluid, one of those wires is twisted round the rod to the right hand, and 

 the other to the left, as low down as the brass collar at the vertex of the lower 

 funnel h, to which they are soldered, to render their contact perfect. The tin 

 funnels hh serve to defend the glasses B and f from the weather, which glasses 

 are also covered with sealing-wax to render their insulation more perfect. At a 

 convenient height from the floor, a hole is bored through the wall at i. This 

 hole receives a glass tube covered with sealing-wax, through which a strong brass 

 wire proceeding from the rod is conveyed into the room, where just at the end 

 of the glass tube it passes through a 2 inch brass ball l, and proceeding a little 



