Analysis of an hydraulic engine. i45 



tened cloth. The pieces of charcoal ufed are made from very ternately con. 

 denfe wood, fuch as box, or lignum vite ; and in this cafe the "^andflipToif 

 fluids will not penetrate into them by capillary attraction, wet cloth. 

 much beyond the places of their primary contact. Their forms 

 are thofe of arcs, fo that each piece connects together two 

 glafles ; but in inftances where fingle pieces of charcoal can- 

 not be obtained of the proper fliape, two long and- thin flips 

 may be fattened together by filk, fo as to form the angle ne~ 

 ceifary to their inlertion into the glaffes. 



4. Twenty feries in a battery of this kind produce fenfible Its power* 

 but feeble fhocks, and when a fingle metallic feries with a 



gold wire and two glaffes of water is fubftituted for one of the 

 primary feries, hidrogen is given out by the metallic point in 

 the glafs of water in the place of the acid, whilft oxigen is 

 evolved from the point in the other glafs. 



5. In the galvanic batteries with charcoal, fulphuric acid Other fluids* 

 may be fubftituted for nitric acid ; and folution of fulphuret of 



potaui for the water, without any material alteration in the 

 nature of the agency ; the folution of the fulphuret indeed, 

 feems, in Tome meafure, to increafe its intenfity, and com- 

 binations containing this fubftance, denfe charcoal, and con- 

 centrated nitric acid, appear to be fuperior in activity to fimi- 

 lar combinations containing copper and the fame fluid ele- 

 ments, and to be nearly equal to thofe compofed of zinc, fil- 

 ver, and water. 

 January 9, 1802. 



XIII. 



Short Analyfis of the Principles and Struclure of Mr. Close's 

 Hydraulic Engine.— W. N. 



J\N eminent engineer, to whofe talents and invention fo- An explanation 

 ciety is highly indebted, writes to me that he cannot under- of Mr. c M e " % 

 Hand Mr. Clofe's engines,' and requefts fome explanation, as e <i # 

 he does not conceive that impoflibilities would have my fanc- 

 *ion. Though I am convinced that an attentive revifal of the 

 defcriptions would render my elucidation unnecefTary, yet as 

 that which he requefts may not be unacceptable to other 

 readers, I have here annexed a few obfervations ; viz. 



Vql. I.— ^February. L 1. That 



