. The microscope : an introduction to microscopic methods and to histology. Microscopes. 288 MICROTOMES AND SECTION KNIVES \_CH. X The microtome knives shown on the various instruments figured in this chapter illustrate well the proper form of section knives. (Figs. 227, 238.). Fig. 227. Section knife with the honing back in position (Cut loaned by the Spencer Lens Co.) § 435. Sharpening Section Knives ; Hones and Strops.— Perhaps it should be taken for granted that any one would appre- ciate the impossibility of making good sections with a dull section knife, but experience teaches the contra
. The microscope : an introduction to microscopic methods and to histology. Microscopes. 288 MICROTOMES AND SECTION KNIVES \_CH. X The microtome knives shown on the various instruments figured in this chapter illustrate well the proper form of section knives. (Figs. 227, 238.). Fig. 227. Section knife with the honing back in position (Cut loaned by the Spencer Lens Co.) § 435. Sharpening Section Knives ; Hones and Strops.— Perhaps it should be taken for granted that any one would appre- ciate the impossibility of making good sections with a dull section knife, but experience teaches the contrary. Students are prone to believe that with one of the elaborate automatic microtomes, good sections may be made with any kind of an edge on the knife. It is forgotton that the knife is the most important part, all the other mechanism is simply its servant. For sharpening, select a fine, yellow Belgian hone, and a very fine Arkansas hone. As a rule hones from the factory are not suffi- ciently plane. They may be flattened by rubbing them on a piece of plate glass covered with moderately fine emory or carborundum wet with water. Round the corners and edges of the hones on the plate glass or on a grindstone. In using the Belgian hone for sharpening knives, wet the surface well with a moderately thick solution of soap. With the Arkansas stone use some thin oil— xylene or kerosene mixed with a little olive oil or machine oil. Honing. Before honing a section knife, make sure that the edge is smooth, that is that it is free from nicks. Test this by shaving off the surface of a block of paraffin. If nicks are present the cut surface will show scratches. It is advisable also to look at the edge of the knife with a magnifier and with a low power (50 mm.) objective. If nicks are are present remove them by draw- ing the edge along a very fine Arkansas Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - co
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