162 METTALLOIDS. 



strings, by pouring molten sulphur from a test-tube, 

 into cold water. 



389. SULPHUR CRYSTALS. Sulphur may 



How may crys- 



talsof sul- be obtained in a crystalline form, by melt- 

 *tained? * n ^ * n a P^P 6 bowl, at a gentle heat, and 



then allowing it to cool. A crust 

 soon forms on the top, which is broken, and a 

 portion of the liquid sulphur below, poured out. 

 On breaking the pipe, it. is found filled with crystals, 

 shooting across the interior, from the encrusted walls. 



SULPHURIC ACID. 



Describe sul- 390. DESCRIPTION. Sulphuric acid is a 

 phuric acid. colorless, oily fluid, of intensely acid taste, 

 known in commerce as oil of vitriol. It is composed 

 of sulphur and oxygen, in the proportion of one atom 

 of the former, to three of the latter. It also contains 

 Water, with which it is chemically combined. As 

 it is among the most important of all chemical 

 products, the process of its manufacture will be given 

 with some detail. 



391. PREPARATION. Sulphuric acid may 



How may sul- . . 



phuric acid be be made directly, from its elements, by ig- 

 prepai nithig a mixture of air and vapor of sul- 



phur, with a red-hot 'iron. In quantity, it is always 

 made from sulphurous acid, by imparting to the latter 

 additional oxygen. Take a bottle in which sulphur 

 has been burned, and which, therefore, contains sulphur- 

 ous acid, and hold in it, for a short time, a rod or stick 



