SULPHURETED HYDROGEN GAS. 61 



bi-carbureted hydrogen, the flame of which much 

 exceeds in whiteness and brilliancy that of coal 

 gas, which is a mixture of the two species of hydro- 

 carbonates. Another material advantage in the use 

 of the oil gas is, that it is not mixed with the impu- 

 rities of coal gas, many of which are highly inju- 

 rious to health, and to the furniture of houses. 

 From experiments it appears that the coal gas does 

 not contain above 10 per cent, of bi-carbureted 

 hydrogen ; while the oil gas consists almost entirely 

 of it. 



Sulphureted Hydrogen Gas. 



This is a combination of hydrogen gas with sul- 

 phur. It has an extremely fetid odour. It is in- 

 flammable. It cannot support life nor combustion : 

 indeed, it is highly deleterious. Water can absorb 

 it, and acquires its peculiar smell. The mineral 

 waters of Harrowgate and Aix-la-Chapelle owe 

 their properties chiefly to this gas. 



Sulphureted hydrogen gas has the property of 

 causing metallic oxides to re-approach the metallic 

 state ; the hydrogen of the gas attracting the oxy- 

 gen. If a piece of paper, dipped in a solution of 

 acetite of lead, be exposed to this gas, it instantly 

 becomes blackened. If letters be written with the 

 solution of lead, they will be invisible when dry, 

 but will become black on exposing them to sul- 

 phureted hydrogen. 



It has also acid properties. It unites with the 

 alkalis and the earths, forming compounds called 

 Hydro-sulphur ets. 



This gas affords an exception to the doctrine of 

 Lavoisier, that oxygen was the only acidifying prin- 

 ciple ; for in it there is no oxygen, yet it performs 



