THE MICROSCOPE. 25 



wood, you must heat a glass slide over an argand burner. Take a 

 pen-knife, and with the blade, move the specimen gently to the 

 edge of the wood. Put the knife-blade under the edge that pro- 

 jects beyond the wood; steady your hand on the side of the wood, 

 do not attempt to lift the section, but draw it off the wood gently; 

 the water from the condensed steam will keep it attached to the 

 knife. Put a drop or two of warm balsam on the heated slide. 

 Have ready a slide template covered with paper, having a circular 

 hole cut in the middle of it, five-eighths of an inch in diameter, or 

 the same size as the specimen. Put the template under the heated 

 slide, holding both in the left hand. 



Dry the free side of the specimen (still on the knife) over the 

 argand lamp. Place the specimen gently on the balsam, directly 

 over the hole in the template. Draw the knife off sideways. If 

 you attempt to lift it up, the specimen will break in pieces, the 

 water holds the section so firmly to the knife. Heat a three-quarter 

 inch glass cover over the argand lamp, and put two drops of balsam 

 on it. Lay it gently on the specimen, which by this time should be 

 perfectly flat. Do not squeeze; heat the template, slide, and section 

 over the lamp, and let the balsam gently boil, to expel the air-bub- 

 bles. Again, do not squeeze, but keep the object in position over 

 the template with the point of the knife-blade. Allow the slide to 

 cool a little. Now gently squeeze down the glass slip so as to expel 

 all superfluous balsam. 



The specimen is thus safely mounted and entirely free from 

 air-bubbles and dirt. In this way I have made hundreds of trans- 

 parent sections of traps, basalts, porphyrites, pitchstones, obsidians, 

 granites, limestones, flints, agates, jaspers, fossil wood, teeth, corals, 

 etc. This process is also suitable for making transparent sections 

 bone, ivory, etc., and is much superior to the old method of rubbing 

 down a specimen fixed with balsam to a glass slip. I have tried 

 both methods. You may now enjoy the fruit of your labors, by ex- 

 amining the finished section under the microscope. 



Many rock-sections show very line natural colors, but the 

 polariscope works wonders in giving splendid shades of colors and 

 defining the crystalline structure of the igneous rocks; whilst on the 

 other hand, many limestones, black-band ironstones, etc., are seen 

 to be made up of myriads of minute fossil organic structures, closely 

 compacted together in a " paste " of granular matter. 



