Scientific Reviews. 261 



possibility of succeeding by the method he has adopted. He may 

 comfort himself by the words of Virgil, 



" Si Pergama dextr4, 

 Defend! possent, etiam hac defensa fuissent ;" 



or by the ancient quotation of Longinus, 



" fttycixaif avXivtcum* 'cftMf tvysm ctfuc^rmfca ;" 



being assured that naked theory will rarely pass now for true 

 philosophy, and that while theoretical views are little regarded, 

 even when propounded by experimental men, they are not likely 

 to call forth greater attention from the pen of a merely speculative 

 philosopher. Another thing we must say. Had our author called 

 his book an attempt, we should have felt bound to notice it favour- 

 ably as an able and ingenious attempt. Had he sent it forth as a 

 view of the way in which nature may posnbly have gone to work, 

 we should have said it was a cxirious and interesting production, 

 and highly deserving of being read ; but advancing, as he does, so 

 decidedly, and laying down the law as if nature had kindly called 

 him to her councils, we are obliged to show upon what shaUow and 

 insufficient grounds he has generally proceeded. 



We shall state then first what we are prepared to admit on the 

 subject of atomic chemistry. 



1. We admit as probable that the atoms of all bodies are angu- 

 lar, and for this simple reason, that cleavage, carried as far as we 

 may, never shows us any thing but angular fragments. 



2. That these angular atoms are aU definite geometrical forms. 



3. That the ultimate atoms of whole families of bodies, while 

 they differ both in mechanical and chemical properties, agree in 

 having the same geometrical forms ; or, in other language, are iso- 

 morphous. 



4. That a chemical atom denotes probably several ultimate 

 atoms. 



5. That a limited variety of atoms, differently arranged and 

 united in different numbers, may produce compounds possessing 

 very different properties, as we find to be actually the case in the 

 animal and vegetable kingdoms. 



6. That the simple or undecompounded substances of chemistry, 

 may therefore be compound, and may possibly be formed in fa- 

 vourable circumstances, though we have as yet no experimental 

 proof of such being the case. 



Thus far we are warranted in going ; our third and fifth posi- 

 tions being the only ones that have been demonstrated. 



Mr. M 'Vicar, from certain considerations connected with its 

 form as the most perfectly angular, assumes the regular tetrahe- 

 dron to be the shape of his universal atom. Invested with subtle 

 matter, these tetrahedrons form the radiant medium,— this also is 



