Magnetism, Cohesion, Adhesion and Viscosity. 517 



nature ; but in the case where the magnetic needle has been 

 the coercing agent, and the measures indicate low intensities, 

 and where the connexion was made with much difficulty, I 

 should draw a contrary inference. This view is strongly 

 supported by what took place with the cornelians. 



The two extremes of the preceding scale give two alloyed 

 metals as the highest and the lowest, namely, brass and the 

 magnet. In seeking for two unmixed bodies that should pro- 

 perly represent the natural scale in the mineral kingdom, that 

 is, one in which the magnetic needle is not arbitrarily as- 

 sumed as the standard of reference, but one that considers the 

 natural classes of substances, I would prefer taking platinum 

 and diamond, and exclude brass and the magnet. The first 

 would take the lead of all metals, namely metalloids, while 

 diamond would be placed at the head of all substances of the 

 vitreous class, or haloids, that is to saj', all the precious stones 

 and all crystals; platinum as the heaviest, and diamond as 

 the hardest of all known bodies. The class of metalloids will 

 be as naturally closed by potassium, as it will be seen the 

 haloids are by gum, two of the lightest of the metallic and 

 vitreous classes of bodies. The reason for adopting this clas- 

 sification is, that I find that iron, from which the magnet is 

 formed, has no remarkable affinity for other bodies, nor for 

 itself, and that the magnet, constituting an exception to the 

 rule of nature, is itself dependent for its exalted effi;cts upon 

 electricity and other extraneous causes, and could only keep 

 its high position while attractive affinity, by our ignorance of 

 natural laws, was supposed to be exclusively its peculiar pro- 

 perty. Such a division is by no means meant to undervalue 

 the importance of the magnet ; for though it has led to the 

 discovery of the affinities of all the rest, there can be no doubt 

 it exists by an exceptional law ; and we might as well {)lace 

 iron at the head of all metals, because we are indebted to it 

 for the implements which have enabled us to penetrate to those 

 very metals. The term magnetism therefore will always main- 

 tain its ground as the general exjjression of the magnetic at- 

 tractions which connect all bodies together, even though they 

 have nothing to do with iron: in the same way that the term 

 electricity has been extended to all those phaeiiomena in which 

 attraction or repulsion result from friction, and yet having not 

 the slightest resemblance to the electron or amber that led to 

 their discovery. 



In the mineral kingdom, metallic and crystalline bodies 

 form the mass of its constituents, and they generally stand 

 clearly contrasted with one another; yet ))latinum as well as 

 diamond, anil all vitreous substances, have a reujurkable affi- 



