COMBUSTIBLE GASES. 173 



part of the State. Although it often passes througli water, it is but sparingly absorbed by it. 

 Its origin, like that of many of the other gases which are evolved from the surface, is probably 

 deep seated. 



SULPHURETTED HYDRCXiEN. 



SuliiIuuTttcd Hydrogen Gas. Ch-nvrUind, — Sul[iliureltcil Hydrogen. Shrpanl. — Sehwcfliges Hydrogen-Gas. 



Miihs. — Hydroginc Sidfure. Bctidaiit. 



Description. Gaseous, colourless, transparent ; absorbed by water. It lias a very offen- 

 sive taste and odour resembling that of rotten eggs, by which it can be distinguished from all 

 other gases. It is heavier than atmospheric air, its specific gravity being 1177, and that 

 of air 1000. 



This gas is highly inflammable, and burns with a pale blue flame ; but it extinguishes burning 

 bodies, and cannot be safely breathed in any quantity. With o.xygen gas it forms a mixture 

 which detonates by the application of flame, or by the electric spark. It blackens the salts of 

 lead, and many other metallic compounds. 



Composition. Sulphur 94.18, hydrogen 5.82. It contains, therefore, one atom of each 

 of the constituents. Its formala will be SH. 



Uses. In addition to the medical virtues which are ascribed to this substance, it is an ex- 

 tremely useful reagent in the laboratory. It is employed in the gaseous form, in solution in 

 water, and in combination with ammonia as a test for the metals. 



LOCALITIES. 



This gas is abundantly evolved in various parts of the State, and it forms what are called 

 Sulphureous, SulpJaurttcd or Hydrosulphurettcd Springs. Of these, a detailed notice, to- 

 gether with an examination of the theorjr of their origin, will be found in the lii'st part of this 

 work (page 141). 



PHOSPHURETTED HYDROGEN. 



Phospliorigcs Ilydrogen-Gas. Mo/is. 



Description. Gaseous, transparent, colourless ; sparingly absorbed by water. It has an 

 offensive smell resembling that of garlic. Its specific gravity is 1185, compared to air as 

 1000. 



This gas does not support flame or respiration, but is characterized by inflaming spontane- 

 ously when mixed with air or with oxygen gas. 



Composition. Phosphorus 91.29, hydrogen 8.71, or one atom of the former and three 

 atoms of the latter. Its formula is PH3. 



