li'^t* SCIENTIFIC N£WS. 



SCIENTIFIC NEWS. 



Extradt of a Letter from Brugnatelli, concerning the 



non-€xijlence (f the charged Pile *. 



V OLTA has made many experiments on piles compofed oi 

 a fingle metal, and a lingle wet flratum, which, from being 

 inadive by themrdves, become more or lefs active after af- 

 fording a palfage for a longer or ftiorter fpace of time to ai> 

 eledric current fet in motion by a61ive pile, &c. 

 Ritter affertcd Kilter, the moft judicious of the galvanic philofophers oi 

 that a pile com- Germany, has aflerted, as Volta fays, that the a6^ive pile, 



pofed ot one ^^ common ele(5trometer, tranfmits a real charge to the pile 



fluid, and one * & r 



metal, was capa- that is itfeif ina6tive, which it therefore calls the charged pile. 



ble of being VoIta however has convinced himfelf, that no charge is 



other pile, tranfmilted, but, by virtue of the ordinary chemical aciion, 



but the fa<a is, W^q eledric current being continued, changes the fingle wet 



' nvert^ed ^nto ^ratum inlerpofed between two pieces of gold, for example, 



two d fFerent into tvvo different fluids, one acid, by which the ele6tric 



ftuids by the current iffues out of the metal, and the other alcaline, by 



which it enters; which conftitutes a pile of the fecond order^, 



namely, of one melal and tvvo fluids of different natures, the 



adion of which however does not continue long, becaufe the 



fluids foon mix. 



Mechanical 



Mr. GREGORY of the Royal Military Academy, Wool- 

 work by Mr. wich, has now in the prefs a Treatife on Mechanics, which 

 Ciejiory. is intended to be publiflied in two volumes o<5^avo. The firft 



will be devoted chiefly to the theory, and will be divided into 

 five books under the feveral heads of ftatics, dynamics, hy- 

 droftatics, hydrodynamics, and pneumatics. The fecond 

 volume will be chiefly appropriated to pra^icaland defcriptive 

 fubje^s, and will commence with general remarks, rules, 

 and tables, relative to the nature, conftru6lion, and fimplifi- 

 cation of machinery; the efl'e^s of fridlion, and the rigidity 

 of cords; and eftimates of the varied energy of different 

 firft movers, &c. Thefe will be followed by defcrip.tions 

 arranged alphabetically, of about 100 of the mofl curious, 

 ufeful, and important machines. In this latter part, Mr. 

 Gregory has been promifed communications from fome 

 celebrated civil engineers, fo that he hopes, on tlie whole,, 

 to render the work in fome meafure deferving the attention of 

 thofe who are engaged in the cultivation and improvement 

 eilher of the theory or the pra«5lice of mechanics. 



* Van Mons Journul ds Cbimiey Vol. VI. p. 132. 



