Magnetism, Cohesion^ Adhesion and Viscosity. 4)53 



The present class exhibits many various degrees of attraction 

 for the magnetic needle, but the ruby, the emerald, the sapphire 

 and the jargoon, it will be seen, stand high in rank for this 

 propert}', while tourmaline and oural emerald are but low. 

 The diamond was the only one of these precious stones that 

 was placed in contact with the magnet, and it was found to 

 have its energy raised by the connexion. Though the dia- 

 mond does not exhibit much attraction for the magnetic 

 needle, it will be seen hereafter that this is compensated for 

 by its affinity for copper, platinum and glass of every kind ; 

 and it will be generally found that what is of difficult connec- 

 tion with the magnetic needle is remarkably the reverse with 

 glass, and they may respectively be placed at the head of a 

 binary division of all substances; and what makes the fact the 

 more remarkable, is that the attractive properties of glass are 

 heightened in a very sensible degree by its remaining in con- 

 tact with the magnet. Glass has a striking affinity for cor- 

 nelian, red and white, and for blood-stone, while a connexion 

 between the magnetic needle and these stones is formed with 

 extreme difficulty. 



It might have been expected that flint would have shown 

 much resemblance to quartz in its attraction for the magnetic 

 needle, but the connexion was always formed with great dif- 

 ficulty, antl on many occasions, though it appears as high as 

 90'', it could not be raised above 20° in some particular spe- 

 cimens, and many were tried. Yet the needle attached itself 

 with great facility at 40° and 50° to quartz, and finally reached 

 90^, but not by any forcing process: that measure however 

 is still its ultimate limit. Flint has a decided repugnance for 

 the magnetic needle, but still the magnet can overcome it, and 

 a refractory specimen was raised by this means from 20° up 

 to 40°. 



4M Class. 



White cameo (artificial). 

 Brown ground of do. 

 Porcelain (dentist's) 74 



Blue enamel 36 



Gypsum-stone 26 



Alabaster 25 



Marble (yellow) ... 10 



Marble (gray) 55 



Slate 30 



Hone 24 



Red chalk. 

 Wliite chalk. 



Crystallized tin 



Iceland spar 90 



Felspar 10 



Selenite 15 



Talc 60 



Sulphate of iron.. 48 

 Protosulphate of 



iron 90x X 



Carbonate of iron 16 



SiJphate o f copper. 



Alum.7..V. 15 



Rock salt. 

 Saltpetre. 

 Sugar candy (white and 



brown). 

 Lump sugar. 



