MICROSCOPICAL EXAMINATION OF FLINT. BY 5, 
| powder should be spread very thinly on a plate of glass, 
with or without water, and by the aid of a lens of moderate 
_ power the roundish grains should be selected and picked up 
with fine forceps, or the point of a needle, and transferred to 
another piece of glass, having on one spot a thin coat of 
Canada balsam. This should be gently heated over a spirit 
_ lamp, when the balsam will penetrate the grains, and render 
them transparent ; by this process the minutest shells, é&c. 
_ may be detected. For a hasty exploration, the dust may be 
_ rendered sufficiently transparent by a drop or two of oil of 
_ turpentine. 
le gh AE = 
Sandy calcareous marls may be examined by diffusing a 
few grains in water in a wine-glass, the lighter portions will 
_ be suspended in the fluid, and may be placed on glass, and 
_ when dry prepared with Canada balsam in the usual manner. 
Frint.— Flint, and other siliceous stones, require to be 
_ chipped into very thin fragments, and immersed in oil of 
turpentine. A clear, translucent flint should be selected, 
_ from which fragments may be shattered off by smart blows 
of a hammer, over’a sheet of white paper: the most trans- 
parent flakes are tobe-selected, and these should be put in 
oil of turpentine, in a wide-mouth glass bottle. Take out 
_ the pieces for examination with forceps, and inspect them as 
transparent objects, by transmitted light. When good speci- 
_ mens are discovered, mount them in Canada balsam. 
Tt is hazardous to entrust such fossils to the lapidaries ; 
an interesting group of twenty spiniferites was reduced to 
- ten, by one of our best workmen, in whose hands it was 
_ placed for polishing, with the view of rendering it more 
_ transparent. 
