BORON. 197 



485. PETRIFACTIONS. As wood wastes 

 What is the 



cause of pet- away in certain sihcious waters, the par- 



rifaction? 



of the departing atoms, and thus copy the wood in 

 stone. Such copies are called petrifactions. 



BORON. 



What is 60- 486. DESCRIPTION. Boron is a brown 



ron ? powder, never seen except in the chemists 



laboratory, and of no practical value. It occurs in 

 nature, combined with other elements, as borax arid 

 boracic acid. 



487. BORACIC ACID. This acid is com- 



Hoio 'is bora- 



cic acid form- monly seen in the form of white pearly 

 scales. It exhales with volcanic vapors 

 which issue from the earth in Tuscany. These va- 

 pors are condensed in water, and the solid acid is 

 obtained by evaporating the solution. The acid is used 

 like borax, as a flux. It is bitter, rather than sour, to 

 the taste, but is called an acid because it forms salts. 



HYDROGEN. 

 488. DESCRIPTION AND OCCURRENCE. 



What is hy- i i AS 



drogen? Hydrogen is a colorless gas, about one fif- 



occurl dOCS U teenth aS heaV y aS the air ' li 1S f SUch 



extreme tenuity, that it may be blown 

 through gold leaf, and kindled on the opposite side. 

 One-ninth part of the ocean, and the same proportion 

 of all water in existence, is hydrogen gas. It enters, 



