TOOLS 
169 
the other concaved. In most of the razors of American make 
the steel is too hard and brittle, as a consequence the edges 
chip, necessitating frequent grinding and honing. It is there¬ 
fore advisable to try and obtain 
a section razor whose steel is 
hard enough to hold a fairly 
keen edge, but not so hard that 
fragments are chipped out by 
any hard particles which may 
be encountered in the material 
being cut. The edge should 
turn, not chip. Small pieces of 
soft material to be roughly sec¬ 
tioned may conveniently be held 
between pieces of elder pith and 
clamped in the jaws of the 
microtome; a few drops of alco- Fig. io6. Small “ Table ” Microtome, 
hoi applied to the pith causes it Spencer Lens Co. 
to swell and to hold the specimen tightly in place. Imbedding 
in paraffin or celloidin is of course much better. ^ 
Tools, etc. — A Jeweler’s hack saw with wide and narrow 
blades (Fig. 107) will be required to cut off bits of metal and 
Fig. 107. Jeweler’s Hack Saw. Sections of blades are shown full size. 
alloys, to cut through specimens to study the thickness of coat¬ 
ings, platings or enamels (most enamels cannot be cut with a 
hack saw); to cut through primers, fuses, etc., in the study of 
ammunition, etc., etc. These tiny hack saw blades are very 
^The student will find in Gage: The Microscope, 13th Ed. 1920 (Comstock 
Pub. Co., Ithaca, N. Y.), detailed directions for imbedding methods. 
