420 KANSAS CITY REVIEW OF SCIENCE. 



scope, is easily recognized. Similar deposits have been made known by dredg- 

 ing the bottom of the sea. According to Professor Joseph Le Conte, in the 

 deeper parts of Lake Tahoe, which sediments do not reach, the ooze is composed 

 wholly of diatoms or infusorial shells. 



Dusty showers of a grayish or red colour are not unfrequent on the Atlantic 

 and Indian Oceans near the coast of Africa. Ehrenberg examined this dust and 

 found it to consist largely of diatoms. He estimated the quantity let fall during 

 a dust shower in the year 1846, near Lyons, at 720,000 pounds, one-eighth of 

 which was diatomaceous, or 90,000 pounds, equal to forty-five tons. Diatoma- 

 ceous earth may be distinguished from other formations of a similar appearance 

 'by its insolubility in acids, extreme lightness, power of absorbing Hquids, and 

 property of polishing metals. It is instantly recognized under the microscope 

 in the hands of one who is familiar with its use. Diasomaceous earth has its 

 uses as well as its scientific, interest. It is largely consumed as a polishing powder 

 under the name of tripoli, from the locality which first gave it to commerce. It 

 is known in California by the absurd name of electro-silicon, and at the East by 

 a variety of trade names. It is a very convenient source of soluble sihca, em- 

 ployed in the manufacture of silicate of soda or potash, also known as soluble 

 glass. The manufacture of this compound is simplicity itself. Carbonate of soda 

 or potash, as the case may be, is dissolved in boiling water to saturation, in a 

 capacious iron kettle, and fresh hydrate of lime added until all the carbonic acid 

 is precipitated and the alkali becomes caustic. Diatomaceous earth in a pow- 

 dered state is then added as long as silica is dissolved, and the whole covered and 

 allowed to cool. When the insoluble matters have settled the clear liquid is 

 ■drawn off and evaporated in a clean vessel to the required density. 



Diatomaceous earth is also used in the manufacture of porcelian, and it is a 

 constituent of certain cements and of artificial stones. At one time it was claim- 

 ed to be a fertilizer, but this is thought to be a fallacy, although Ehrenberg 

 states that the fertilizing power of the Nile mud is furnished by fossil infusoria. 



Slabs of diatomaceous earth absorb liquids with avidity, and are used in lab- 

 oratories for drying crystals and filters. This property might be more generally 

 utilized if better known. A convenient contrivance for lighting fires is a lump of 

 diatomaceous earth with a handle of stout iron wire. It is dipped into a 

 vessel of petroleum, placed in the stove or fire place, and lighted with a match. 

 It continues to burn safely for some time. 



Bricks that float in water are made of diatomaceous earth mixed with one- 

 twentieth part of clay and well burned. The art of making these floating bricks 

 was well known in the time of Pliny, but was afterward lost. It has recently 

 been discovered. In the Italian department of the Paris Exhibition of 1878, 

 these bricks were exhibited, which attracted considerable attention. Floating 

 bricks, made wholly of California material, may be seen in the State Museum. 



Kieselghur, or "flint froth," of the Germans, from a deposit in Hanover, 

 is extensively used in the manufacture of dynamite, giant powder, lithofracteur, 

 and other explosives. Diatomaceous earth absorbs from three to four times its 



