Chap. 3 .~\ Subftances extfting In tie Pores of other Bodies. 1 1 



actual properties of matter, we ought, I apprehend, to 

 confine ourfelves to the teftimony of our fenfes. 



How improperly the idea of impenetrability is ap- 

 plied to any bodies which we are acquainted with, is 

 evident from the aftonifhing eafe and velocity with 

 which the electric fluiJ pafles through the denfeft bo- 

 dies, and from the continual paffage of light through 

 a Variety of Jubilances, which afford to our fenfes the 

 moft perfect idea of folidity, through glafs, and dia- 

 mond, and other precious ftones; the focus of a burn- 

 ing mirror, which augments the denfity of the fun's 

 rays upwards of three thoufancl times, may be received 

 in glafs or water without producing any effect : even 

 fubftances of fenfible bulk and folidity can exift within 

 the pores of other bodies. Thus quickfilver exifts 

 within the pores of either filver or gold; in fact a mix- 

 ture of mercury and filver is considerably heavier than 

 an equal bulk of either of thofe metals. The com- 

 mon bell-metal is a mixture, of copper and tin j and 

 though the latter is fpecifically lighter than the former, 

 yet bell-metal is confiderably heavier than an equal 

 bulk of copper itfdf ; which is an evident proof that 

 the particles of the one actually enter into, and are de- 

 pofited in the pores of the other. 



The dwifibility of matter is alfo received with limi- 

 tation by thofe who contend for the exiftence of atoms 

 or firft principles of bodies j fince, if their exiftence is 

 admitted, there muft neceflarily be fome parts or ;or- 

 tions of matter indivifible, and confequently it cannon 

 be admitted as a property inherent in a]\ matter. 



The human faculties are loft in the p rfuit, and 

 the human understanding in the contemplation of the 

 actual ciivifibility of matter. The fmallcft animalcula 

 which is brought within our notice by the microfcope 

 poflbfles organized parts, blood and other fluids ne- 



ceflarv 



