[22] 



®n 2)iatom0* 



By Thomas Partridge, M.K.Q.C.P. 



IT is not my intention in this paper to offer any description of 

 these curious structures, their mode of growth, develop- 

 ment, or peculiarities, all of which have been often explained 

 already ; but merely to give a few disconnected and brief notes 

 and ideas that have been brought to my notice lately. 



These interesting and peculiar organisms are found nearly 

 everywhere, and though usually invisible to the naked eye, they 

 exist in myriads, and, as Pritchard in his " Infusoria," says (p. 

 305), ^^ Play a viore impoi'tant pa7't in fornmig the earth's crust than 

 even the gigantic Satirians of the past.'' 



Diatoms are found in the Eocene, Miocene, Pliocene, and 

 Chalk formations, and even the Oolitic are not zuithoiit traces of 

 them. A deposit of diatomaceous earth was found 400 miles 

 long by 120 wide in Victoria Land; and the town of Richmond, 

 Virginia, is built on a bed of diatoms 18 feet deep and unlimited 

 in extent. The deposits at the bottom of lakes are composed of 

 this material, as may easily be seen on examination of the mud. 

 The polishing slate of Bohemia, " Turkey stone " and " Rotten 

 stone," are composed chiefly of diatoms, and in our own country, 

 North Wales, Ireland, and Scotland, large deposits are found; 

 while in Sweden and Norway, the Bergh Mehl, or Mountain-Flour, 

 is composed of diatomaceous earth, which is supposed to possess 

 some nutritious properties. In the last report of the State Min- 

 eralogist for California, Mr. G. H. Hanks says that diatomaceous 

 earth is being used in that country for numerous purposes ; among 

 others — 



I. — To make Silicate of Soda and Potash for the manufac- 

 ture of Porcelain. 

 2. — Slabs of it are used as absorbents in laboratories. 

 3. — Floating bricks were used in the time of Pliny. The 

 secret of making these had been lost, but was lately 

 re-discovered, diatomaceous earth being mixed with 

 I — ^2oth part of clay and burnt. Specimens were to be 

 seen in the Paris Exposition of 1878. 

 4. — A lump of diatomaceous earth fixed on to the end of a 

 wire and dipped in petroleum makes a good fire-lighter, 

 and can be used over and over again. 

 5. — In Germany, the " flint-froth " is used in the manufac- 

 ture of dynamite, as it absorbs four times its weight of 

 nitro-glycerine. 



