SULPHURIC ACID, AND SULPHURETTKD HYDROGEN. 185 



wliich disappears with the oxygen of the atmos[)here, and are known 

 to chemists by the name of sul[)hurous acid. This compound is des- 

 tructive to animal and vegetable Hfe, but as it is not known to be directly 

 formed to any extent in nature, except in the neighbourhood of active 

 volcanoes, it probably exercises no extensive influence on the general 

 vegetation of the globe. 



This gas possesses the curious property of bleaching many animal and 

 vegetable substances. Wool and straw for plaiting are bleached to an 

 almost perfect whiteness — when they are suspended in a vessel or room 

 into which a plate of burning sulphur has been introduced. Gardeners 

 sometimes amuse themselves also in bleaching roses and other red 

 flowers, by holding them over a burning sulphur match. Some shades of 

 red resist this action more or less perfectly, and the colour of the bleached 

 flowers may often be restored — by dipping them in a dilute solution of 

 carbonate of soda, or by holding them over a bottle of hartshorn (liquid 

 ammonia). 



3. Sulphuric acid. — This is the name by which chemists distinguish 

 tlie oil of vitriol of the shops. It is also a compound of suhihur and oxy- 

 gen only, and is formed by causing the fumes of sulphur to pass into 

 large leaden chambers along with certain other substances, from which 

 they can obtain a further supply of oxygen. 



It is met with in the shops in the form of an exceedingly sour corrosive 

 liquid, which decomposes, chars, and destroys all animal and vegetable 

 substances, and, except when very diluted, is destructive to life in every 

 form. It is rarely met with in nature, in an uncombined state, — though 

 according to Boussingault, some of the streams which issue from the 

 volcanic regions of the Andes are rendered sour by the presence of a 

 quantity of this acid. 



It combines with potash, soda, lime, magnesia, &c., and forms sul- 

 phates which exist abundantly in nature, and have often been benefi- 

 cially and profitably employed as manures. 



Where the soil contains lime or magnesia, the acid may often be ap- 

 plied directly to the land, in a very dilute state, with advantage to clover 

 and other similar crops. It has in France, near Lyons, been observed 

 to act favourably when used in this way, while in Germany it has been 

 found better to apply it to the ploughed land, pre-vious to sowing. A few 

 experiments have also been made in this country with partial success. 

 It is deserving, however, of a further trial, and in more varied circum- 

 stances. 



4°. Sulphuretted Hydrogen. — This gaseous compound of sulphur 

 with hydrogen, is almost universally known by its unpleasant smell. 

 It imparts their peculiar taste and odour to sulphurous springs, such as 

 that of Harrogate, and gives their disagreeable smell to rotten eggs. It 

 is often produced in marshy and stagnant places,* and fish ponds, where 



* Thia appears to be especially the case on the coasts of Western Africa, where the 

 hot sun is continually beating on sea water, often shallow, frequently stagnant, and always 

 laden with organic matter, either animal or vegetable (Daniell). Near the mouth of the 

 Tees in this county, where a shallow, dark blue, muddy, samphire-bearing tract stretches 

 for several miles inland from Seaton Snook, the presence of sulphuretted hydrogen may be 

 perceived by the smell, when on a hot summer's day a gentle air skims along the edge of 

 the Slake. The favourable conditions are, a burning sun, a very gentle air, and such a con- 

 dition of the sea— tJiat those parts and pools which are only reached by the ti)ring tides 

 shall have been several days uncovered. 



