88 SULPHUR. 



and by various processes we are able to obtain com- 

 pounds of nitrogen, with most other elements, setting 

 out with this acid as a source of nitrogen ; for it 

 seems that nitrogen hardly ever will combine with an 

 element, except when in the nascent state ; that is, 

 when being evolved or set at liberty by the decom- 

 position of a substance, in which it was already com- 

 bined with some other element (769). 



170. There are three other elements deserving 

 notice, which, like nitrogen, are of little interest in 

 themselves, but which, by combining with other sub- 

 stances, form important compounds; these are sul- 

 phur, chlorine, and phosphorus. 



171. The properties of sulphur, or brimstone, are 

 familiar to every one; it occurs native, both pure 

 and also in combination with various metallic sub- 

 stances ; entering into the composition of many ores, 

 such as those of copper, lead, zinc, mercury, &c. 

 Sulphur is a pale-yellow, solid substance, insoluble in 

 water, having hardly any taste, but a faint and pecu- 

 liar smell, melting easily when warmed, and catching 

 fire very readily, burning with a pale-blue flame, and 

 giving out at the same time a peculiar and very dis- 

 agreeable smell. The compounds which sulphur 

 forms with oxygen, and also with hydrogen, are the 

 principal which demand attention. 



172. Sulphur, like nitrogen, is able to combine 

 with oxygen in several proportions, and hence it 

 forms several distinct compounds. It is only neces- 

 sary to describe two of them — sulphurous acid, and 

 sulphuric acid or oil of vitriol. 



