METHODS FOR HANDLING SMALL AMOUNTS OF MATERIAL 297 
crucibles require a special support during ignitions casseroles 
will be found more convenient. 
Grinding, Crushing, Mixing. — For grinding and crushing 
materials for analysis, the smallest available agate mortars are 
best. One not larger than 30 millimeters in diameter, Fig. 159, 
Fig. 159. Agate Mortar for Microchemical Analysis. (Full Size.) 
should be selected. It must be carefully scrutinized with a lens 
to see that its inner surface is properly polished and is free from 
fissures, pits and scratches. A mortar made from a first quality 
piece of agate, if properly cared for, should last a lifetime. 
