I 

 did tECtURE XLfX. * - . 



may be observed, that it requires only a more or less minute division of the 

 matter, to reduce the magnitude of the interstices between the neighbouring 

 particles within any given dimensions. Thus platina contains, in a cubic 

 inch, above 200 thousand times as many gravitating atoms as pure hydrogen 

 gas, yet both of these mediums are free from sensible interstices, and appear 

 to be equally continuous; and there may possibly be other substances in na- 

 ture that contain in a given space 'iOO thousand times as many atoms as pla- 

 tina; although this supposition is not positively probable in all its extent; 

 for the earth is the densest of any of the celestial bodies with which we arc 

 fully acquainted, and the earth is only one fourth as dense as if it were com- 

 posed entirely of platina ; so that we have no reason to believe that there 

 exists in the solar system any considerable quantity of a substance even so 

 dense as platina. 



Besides this porosity, there is still room for the supposition, that even the 

 ultimate particles of matter may be permeable to the causes of attractions of 

 various kinds, especially if those causes are immaterial: nor is there any 

 thing in the unprejudiced study of physical philosophy that can induce us to 

 doubt the existence of immaterial substances; on the contrary we see ana- 

 logies that lead us almost directly to such an opinion. The electrical fluid 

 is supposed to be essentially different from common matter; the general me- 

 dium of light and heat, according to some, or the principle of caloric, ac- 

 cording to others, is equally distinct from it. We see forms of matter dif- 

 fering in subtility and mobility, under the names of solids, liquids, and 

 gases; above these are the semimal:erial existences which produce the pheno- 

 mena of electricity and magnetism, and either caloric or a universal ether; 

 higher still perhaps are the causes af gravitation, and the immediate agents 

 in attractions of all kinds, which exhibit some phenomena apparently still 

 more remote from all that is compatible with material bodies ; and of these 

 diiferent orders of beings, the more refined and immaterial appear to pervade 

 freely the grosser. It seems therefore natiKal to believe that the analogy 

 may be continued still further, until it rises into existences absolutely im- 

 material and spiritual. We know not but that thousands of spiritual worlds 

 may exist unseen for ever by human eyes; nor have we any reason to sup- 

 pose that even the presence of matter, in a given spot,* necessarily excludes 

 these existences from it. Those who maintain tlmt nature always teems with 



