48 ©f ttje gterijantcal ®mint of 



by Aqua fortk i but will by Apa 

 Regis $ whereas Silver is not falli- 

 ble by the latter of thefe Menftru- 

 oms but is by the former. Amd this 

 relative Affeftion 5 on whofe ac- 

 count a Body comes to be corrodi- 

 ble by a Menftmum^ feems toconfift 

 chiefly in three things, which all of 

 them depend upon Mechanical Prin- 

 ciples. 



Of thefe Qualifications the firji 

 is 3 that the Body to be corroded be 

 furmlh'd with Pores of fuch a big- 

 nefs and figure , that the Corpufcles 

 of the Solvent may enter them, and 

 yet not be much agitated in them 

 without giving brisk knocks or 

 (hakes to the folid parts that make 

 up the walls , if I may fo call them, 

 ot the Pores. And 'tis for want of 

 this condition, thatGlafsis penetra- 

 ted in a multitude of places, but not 

 diffipated or diflblv'd by the incident 

 beams of Light, which permeate its 

 Pores without any considerable re- 

 fiftance J and though the Pores and 

 Comrniifures of a Body were lefs 



mi- 



