New Outlines of Chemical Philosophy. 425 



that experimental precision upon which it is necessary to build 

 a theory, I constructed the following simple apparatus: 



1. In fig. 4, Plate VIII. a, b,c is a glass rod of green bottle- 

 glass 2-IOths of an inch in diameter, and eight or ten inches in 

 length, bent to a right angle at b. The end c is fixed into a 

 wooden foot or base EF, so that the part h c may stand in a 

 perpendicular direction. A small perforafion is made by meaiis 

 of the blow-pipe, through the end of the glass rod at («), into 

 which a piece of piano-forte wire is fixed, that stands about an 

 inch and a half above the rod, and reaches three or four inches 

 below it. To the lower end of this wire two slips of Dutch 

 gold-leaf are fixed with gum water. I have tried both gold and 

 silver leaf for this purpose ; but Dutch gold-leaf, commonly called 

 Dutch metal, an article manufactured out of copper, is far pre- 

 ferable. 



The glass jar w, .r, y, «, three inches in diameter and seven 

 inches deep, is fixed into the base EF. The slips of Dutch gold- 

 leaf are each one inch in length, consequently their ends cannot 

 reach the sides of the glass nearer than half an inch when the 

 wire is in the axis of the glass. The only use of this jar is to 

 defend the slips of metal from being agitated by the air, and 

 from the action of the small particles of dust and moisture that 

 are constantly floating in it. 



As green bottle-glass contains no metal, I suppose that it in- 

 sulates better than white flint, which contains much lead. 



2. Another electrometer is made thus: The glass rod a, l, r, 

 being taken away, a stopper of sealing-wax is fitted into the 

 neck of the jar, through which a piece of piano-forte wire passes 

 into the glass, and extends down its axis about one-third ot the 

 distance between the stopper and tlie bottom y z. To the lower 

 end of this wire two slips of Dutch leaf are fixed in the manner 

 above described. 



This electrometer is more convenient for some experiments 

 than the other, and less liable to accidents. 



I have various other forms of this instrument, which need not 

 be described in this paper. 



3. Several insulating stands, each consisting of a glass rod 

 ten inches in length and 2-lOths of an inch in diameter, stand- 

 ing upon a brass foot. These have each a circular piece of plate 

 glass two inches and 3-4ths in diameter, fixed upon its top 

 with sealing-wax. The upper surface of this glass is gilt with 

 gold-leaf, and upon its centre a slip of Dutch leaf about an inch 

 in length is fixed by one of its ends. 



4. A brass ball two inches in diameter, having a slip of Dutch 

 (eaf fixed l)y one of its ends to the top of it, is supported by a 

 brass wjr^ fixed into 9. brass foot. 



5. An 



