71 
others. These agents are undoubtedly not difficult to detect 
by chemical agency, but here again the skilful microscopist 
by the aid of his instrument renders almost certain the 
presence of these agents where chemical evidence hesitates 
with regard to its results. We give the appearance of 
crystals of corrosive subhmate and tartar-emetic under a 
power of only 30 diameters. 
Fie. 4. 
Crystals of tartar emetic magnified 30 diameters, p. 251. 
The substances we have mentioned are those derived from 
the mineral kingdom, which are most commonly used for the 
purposes of self-destruction or the murder of others. At the 
same time it ought not to be forgotten that a large number 
of mineral substances requiring to be exhibited in larger 
quantity are constantly employed in the destruction of 
human life. Of these, the most common are acetate of lead 
and oxalic acid. These substances, though easily detected 
Fie. 5. Fie. 6. Hie. 7. 
86000000 
Crystals of corrosive sublimate, Mercury sublimed from cor- 
30 diameters, p. 227. _rosive sublimate, p. 227. 
