468 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the wood. This is the most critical period in the rubbing process, 

 which must be done very gently. 



In making sections of flints, agates, and stones of like hardness, 

 it is of no use rubbing them on the sandstone ; they must be ground 

 down from the very first on the iron plates with emery. The rest of 

 the process is the same as above. 



When the beech can be well seen through the specimen, a few light 

 rubs should be given on the water-of-Ayr stone, using water. The 

 specimen is then ready to be mounted in Canada balsam. 



Eemove with a wet cloth all the gum from the edge of the 

 specimen, and thoroughly clean the wood of all impurity. Boil the 

 kettle. Stick the blade of a pen-knife into the side of the beech, to 

 act as a handle, and hold the specimen in the steam from the kettle- 

 spout till it slides down the face of the wood. There need be no fear 

 of its falling off. The water from the steam will prevent this. It 

 may come off in less than five minutes, or it may take half an hour. 

 It is useless to try to hasten the process, by pushing the specimen 

 with the edge of the knife-blade ; this will only end in a vexatious 

 smash. After all, on an average, about a dozen specimens can be 

 " steamed " from the wood and mounted in balsam in about two hours. 

 With every care, a specimen will sometimes break in two or more 

 pieces, in which case a slide may perhaps be made of each fragment. 

 The specimen having at last become loose on the wood, heat a glass 

 slide over an aigaud burner, and with the blade of a penknife move 

 the specimen gently to the edge of the wood. Put the knife-blade 

 under the edge that projects beyond the wood, steadying the hand on 

 the side of the wood, and not attempting to lift the section, but draw- 

 ing 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, 5-8ths in. in diameter, 

 or the same size as the sj)ecimeu. 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 argaud lamj). Place the specimen gently 

 on the balsam, directly over the hole in the temj)late. Draw the 

 knife off sideways. If it is attempted to lift it up, the specimen will 

 break in pieces, the water holds the section so firmly to the knife. 

 Heat a 3-4ths in. 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-bubbles. 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. 



Mr. Smith says that the process is also suitable for making trans- 

 parent sections of bone, ivory, &c., and is much superior to the old 

 method of rubbing down a specimen fixed with balsam to a glass 

 slip. 



