126 Remarks on Mr. Dani ell's Theory [Feb. 



specific gravity of the latter solid must, therefore, be greater than 

 that of the former." 



Here is a mathematical demonstration that requires only the 

 Q. E. D. to give it the air and stile of the early geometricians ; 

 it is logical, and, I will venture to say, unanswerable. Adopting 

 the old formula, it may be stated thus : the specific gravities of 

 bodies vary directly as the weights, and inversely as the surfaces. 

 There are many familiar facts (not the less striking on that 

 account) that illustrate and confirm this principle. Gold in its 

 more solid form is one of the heaviest metals ; let it be beaten 

 into gold leaf, i. e. increase its surface, and it will swim upon 

 water ; nay, upon ether. A dry sponge (which, including all its 

 pores, possesses, perhaps, the greatest quantity of surface of any 

 known body of the same size) will swim upon our lightest fluids. 

 Saturate it with water ; i. e. destroy as it were the surface of its 

 pores, and it immediately sinks. Mr. Daniell, however, has 

 adopted a more scientific mode of bringing his theory to the 

 ordeal of experiment. He says, a mass of fluor spar will divide 

 either into octohedrons or into tetrahedrons: " the question, 

 therefore, seems to resolve itself into this : Is the specific gravity 

 of a mass of fluor, split into the form of an octohedron, greater 

 than the specific gravity of the same mass split into the form of 

 a tetrahedron ? " To determine this, he proceeded to try the 

 experiment " with all the care and attention which the delicacy 

 of the investigation required ; " and the specific gravity of the 

 octohedron he found to be 3-037, while that of the tetrahedron 

 was 2*909 : — he adds, " the result of this experiment, therefore, 

 was perfectly satisfactory." Most assuredly it was, but perfectly 

 unnecessary, at least for my convinction • for when once I have 

 satisfied myself of the truth of an hypothesis by mathematical 

 demonstration, I never suffer my confidence to be shaken by 

 facts. 



There are many men who would cavil at this result, and observe 

 that, according to the theory, the specific gravity of the tetra- 

 hedron ought to have been 2-760, fur y : 20 :: 3-037 : 2-760.— 

 An error of two units in the first place of decimals must never 

 be allowed to overturn a theory founded upon a priori mathema- 

 tical deduction. And after all, notwithstanding his precaution, 

 the difference may have arisen from inaccurate manipulation. 

 I, therefore, determined (for proselytes are generally enthusiasts), 

 by experiments more decisive, and conducted, if possible, with 

 still greater delicacy than those of Mr. Daniell, to place our 

 theory (if he will allow me the use of the plural possessive) 

 beyond the reach of controversy. Unfortunately, Sir, not being 

 a mineralogist, I had no fluor spar to recur to, excepting, indeed, 

 two vases, and an obelisk of Blue John, which graced our draw- 

 ing-room chimney-piece ; and, independently of the difficulty of 

 detaching from them either an octohedral or a tetrahedral por- 

 tion, it would have been unfeeling to propose such a sacrifice to 



