14 A POPULAR EXPOSITION OF THE 
loaded with more than 50 or 60 grains in each pan, although often 
of great delicacy when carrying lesser weights. The use of the 
sp gr. bottle requires a chemical balance, costing, at the very lowest, 
some twenty-five or thirty dollars, besides being of difficult porta- 
bility ; and hence its employment for general purposes is scarcely 
available. 
Relative Malleability.—_Some few minerals, as native gold, native 
silver, sulphide of silver, native copper, &c., are malleable or ductile, 
flattening out when struck, instead of breaking. A few other 
minerals, as talc, serpentine, &c., are secti/e, or admit of being cut 
by a knife ; whilst the majority of minerals are brittle, or incapable 
of being cut or beaten out without breaking. In testing the relative 
malleability of a mineral, a snall fragment should be placed on a 
little anvil, or block of steel polished on one of its faces,* and struck 
once or twice by alight hammer. ‘To prevent the fragment from 
flying off when struck, it may be covered by a strip of thin paper, 
held down by the forefinger and thumb of the left hand. Thus 
treated, malleable bodies flatten into discs or spangles, whilst brittle 
ones break into powder. 
Magnetism.—Few minerals attract the magnet in their natural 
condition, although many do so after exposure to the blowpipe. (See 
below.) In trying ifawineral be magnetic, we chip off a small frag- 
ment, and apply to it a little horse-shoe magnet, such as may be 
purchased anywhere for a quarter of a dollar; or otherwise we apply 
the specimen to a properly suspended magnetic needle In this 
manner the black granular masses which occur frequently in our 
gneissoid or Laurentian rocks, and in the boulders derived from 
them, may easily be recognised as magnetic iron ore.| Many speci- 
mens of magnetic iron ore (and also of magnetic pyrites) exhibit 
“polarity,” or attract from a given point, one end of the needle, and 
repel the other. 
Taste.—This is a very characteristic although limited property, 
being exhibited only by a few soluble minerals. In these, the taste 
may be saline, as in rock salt; or bitter, as in Epsom salt; or metal- 
lic, as in sulphate of iron, and so forth. 
* The little anvils called ‘“ Watch-makers’ anvils,’ are very suitable for this purpose. 
They may be purchased (where Watch-makers’ tools are sold) for half-a-collar, or even less.. 
+ The other dark-coloured cleavable masses in these rocks consist of mica or more rarely 
of hornblende. 
