284 Mr. J. Taylor's Lectures on Metallurgy. 



1. Unalterable by fire, or not oxidable by heat; a property which 



foi-merly was supposed to characterize a perfect metal: 

 Gold Silver, Platina, Nickel, 1 ^^^^j^^^^ ^^^^ ^^U^^^^j^^ 



Falladium J 



Rhodium, Iridium granular and brittle. 



2. Oxidable by heat; and, being thus converted into what was 



called a calx, formerly considered as imperfect: 

 Mercury Copper, Iron, Tin, 1 ^^u^^^le. 



L<ead, Z>inc j 



Bismuth, Antimony. -Cobalt, "i 



Manganese, Tellurium, Ti- > brittle, but fusible. 



tanium, Tantalium J 



Uranium, Osmium infusible and granular. 



3. Metals which are acidifiable : 

 Columbium, Chrome, Tungsten, \n ■, 



Molybdena j- nxea. 



Arsenic volatile. 



We may here observe, that of these, 



3 of the first class, 



6 of the first division of the second class, 



4 of the second division of the same, 

 and 1 of the third class, 



or 1 4 species, will deserve most of our attention. 



Principal characters of metallic substances. 

 One of the most remarkable is the peculiar htslre which 

 their polished surfaces exhibit; and which, fi'oni its being 

 eminently characteristic of these substances, has been called 

 the metciUic lustre. 



The next remarkable property of metals is their opacity, 

 which, though very considerable, is by no means absolute as 

 has been affirmed. Leaf gold will transmit a green light, and 

 silver leaf a white light. Probably other metals would also 

 be somewhat transparent if equally attenuated. 



In specific gravity the metals exceed all other known sub- 

 stances. Sulphate of barytes, the heaviest of earthy bodies, is 

 less than 4^ times as heavy as water. Tlie lightest metal is 

 more than 6 times as heavy as water, and the heaviest (pla- 

 tina) is near 23 times as heavy. 



The specific gravity of a few of the pvincipal metals is as 

 under : 



Platina 23 Copper T'S 



Gold 19-25 Iron 7-6 



Mercury ... 13-5 Tin 7*3 



Lead 11-3 Zinc 7 



Silver 10-5 



The 



