78 Selections from Huxley 



to the contrary, the chalk might be a kind of gigantic fur 

 upon the bottom of the earth-kettle, which is kept pretty 

 hot below. 



Let us try another method of making the chalk tell 

 5 us its own history. To the unassisted eye chalk looks 

 simply like a very loose and open kind of stone. But 

 it is possible to grind a slice of chalk down so thin that 

 you can see through it until it is thin enough, in fact, 

 to be examined with any magnifying power that may 



10 be thought desirable. A thin slice of the fur of a kettle 



might be made in the same way. If it were examined 



microscopically, it would show itself to be more or less 



distinctly laminated mineral substance and nothing more. 



But the slice of chalk presents a totally different 



15 appearance when placed under the microscope. The 

 general mass of it is made up of very minute granules; 

 but, imbedded in this matrix, are innumerable bodies, 

 some smaller and some larger, but, on a rough average, 

 not more than a hundredth of an inch in diameter, 



20 having a well-defined shape and structure. A cubic inch 

 of some specimens of chalk may contain hundreds of thou- 

 sands of these bodies, compacted together with incal- 

 culable millions of the granules. 



The examination of a transparent slice gives a good 



25 notion of the manner in which the components of the 

 chalk are arranged, and of their relative proportions. 

 But, by rubbing up some chalk with a brush in water 

 and then pouring off the milky fluid, so as to obtain 

 sediments of different degrees of fineness, the granules 



30 and the minute rounded bodies may be pretty well sepa- 

 rated from one another, and submitted to microscopic 

 examination, either as opaque or as transparent objects. 

 By combining the views obtained in these various methods, 

 each of the rounded bodies may be proved to be a beau- 



