JSlf^roinetry,— Siberian Red Leact. - ^^t 



candles. On the contrary, the eleftrometer of Bennet will fcarcely communicate the 

 kaft portion of its eleftricity to a point not abfolutely in conta£t with its cap } but is- 

 readily deprived of its eledric ftate by a candle. 



Coulomb, by his method of torfion, has determined that the a(^ion of weak cle£lri- 

 cities diminifhes as the fquare of the diftance. I do not know that any experiments have 

 been made to determine the ratio of the repulfion or attraction of bodies by eledtricity,, 

 with regard to the diftance, when the intenfities are confiderable. 



To examine this obje<Et I caufed a brafs condu£tor to be made, four inches in dia- 

 meter, with a fpherical part at each end, of five inches diameter 5 and, on the whole, 

 twenty inches long. It was fixed with its axis in the vertical pofition. In the 

 upper fpherical part there was a flage fupporting a pulley, the axis of which ran upon 

 two pair of very delicate friclion wheels. The lower fpherical part was perforated in the 

 axis, to receive the ftem of a very light fphere of paper gilt, and of the diameter of 

 five inches. Care was taken that this ftem, which was nearly the whole length of 

 the conductor from the friftion wheels to the lower orifice, fliould not touch that orifice j 

 and for greater fecurity there was a fmall frame carrying three fridtion rollers, againft 

 one of which it was fure to bear in cafe of accidental irregularity. The upper part of the 

 ftem was fattened to a fine filken thread which pafled over the pulley, and was tied to a 

 counterpoife adapted by its figure to receive fmall weights, in order that the equilibrium 

 or preponderance might be adjufted at pleafure. On the axis of the pulley was an indejt 

 and hand, which moved upon a face without touching, beneath a convex glafs, and 

 (hewed the defcent of the gilded ball in inches and parts. I expected to have obtained a 

 confiderable fcale on my ftem of twelve inches. But in the trials I made when it was 

 finiflied, in which the afcending power of the ball could be varied at pleafure by addition 

 to the counterpoife, I found either that it did not move at all, or that,, if it did, it ran 

 with confiderable velocity through its whole length. This unexpcdted event, together 

 with fome other imperfeClions in the inllrument itfelf, which required amendment and- 

 alteratiofl, prevented me from purfuing and diverfifying a courfe of experiment that pro- 

 mifed fo little. The fafts appear however to ftiew, that in great intenfities and ihort 

 diftances, the diminution of etreft, if it follow the law of the fquares of the diftances,. is 

 like the attraction of the earth upon projectiles, too fmall to be perceived. But from the 

 indications afibrded by Henley's quadrant eleCtrometer, and the floating eleCtrometer of 

 Nollet, there' appear to be reafons why the purfuic ftiould not be thought unworthy of fur- 

 ther experinasnt. 



IV. 



^nalyfis of the Red Lead of Siberia % imth Experiments on the Neiif Metal it contains. By 



Citizen Vau^elin, Infpeilor of Mines, and Confervator of Chemical ProduEis at tbf 



M.ineralogical School. 



(Concluded from page393, Vol. 11.) 



Combinations of the Acid of Red' Lead luith the Alkalis. 



X H E acid of red lead forms, in Its combination with the alkalis,, falts which arc- 

 foluble,,cr]jftallifable, and cobured. The Cmpleft. procefs for making thefe falts confifts. 



iui 



