1 2 Preparation of Vitriolic Acid. [Book VI. 



genous gas which it affords ; and the acid fumes which 

 are produced are abfcrbtd by the water. The pro- 

 cefs is repeated till the water is thought fufficiently 

 acid. The volatile fumes are then diffipated by ex- 

 pofure to air, and the acid is concentrated by diiiilling 

 off the fuperfluous water. 



The vitriolic acid is faid to have become concrete 

 by cold, but it probably was not in ics moft perfect 

 date. It eafily parts with its oxygen to inflammable 

 fubftances ; if oil is mixed with it, it is converted into 

 a dark, vifcid fubftance, and emits fulphureous and 

 pungent vapours. 



The vitriolic acid has been thought to exift in the 

 atmofphere, but this is a miftake. It is difcovered 

 in fome waters, -but in fmall quantity j it exifts in 

 fome ores of metals, and makes one of the conftituent 

 parts of gypfum. 



The NITROUS acid is a fluid of confiderr.ble weight, 

 but does not admit of fo much concentration as the 

 vitriolic. In its moft perfeft form it is quite tranfpa- 

 rent and colourlefs, but in its ordinary ftafe it is of 

 an orange tawny colour, and when expofed to the air 

 It conftantly emits orange-coloured fumes, which are 

 noxious. It very- readily parts with its oxygen to 

 inflampiable fubftances and metals ; and when mixed 

 with oil of turpentine, it explodes and flames. The 

 oil attrafh the oxygen, and burns, while the azote is 

 fuddenly fet at liberty, and occafions the explofion. 

 n nitrous acid is 1 diluted with an equal weight of 

 T, it is v called aqua fortis. The nitrous acid is 

 considerably dhTufed in nature. All that is fold in 

 the lliops is obtained by diftilling fak-petre with the 

 vitriolic acid. 



Azotic and oxygenous gas were mixed together by 

 Air. Cavendifh, and the electric fpark was palled 



through 



