392 Scientific Intelligence. — Hydrography. 



bonic acid, the author supposes that this gas is generally pro- 

 duced in the interior of the earth, but this chemical process is 

 only more active in volcanic or volcanised places. Muriatic 

 acid and sulphuric acid exist only in springs that are in the vi- 

 cinity of volcanoes in a state of activity. All the saliferous de- 

 posits are of volcanic origin. The air, acting upon the beds of 

 sulphur, produces sulphurous acid and sulphuretted hydrogen. 

 Sulphuric acid may be formed of sulphurous acid or pyrites. 

 Muriatic acid is formed by the action of sulphuric acid upon 

 salt. The carbonic acid circulating in all the volcanic rocks de- 

 composes the alkalies and salts, and 'impregnates the springs 

 with them. The two other volcanic acids also act ; and thus is 

 explained the formation of mineral springs. In the fourth 

 chapter, the author considers the composition of mineral waters, 

 the merit of their analysis, and of their artificial recomposition, 

 their imponderable parts, the existence of mutually decomposing 

 salts, &c. The following are the results of the analyses of these 

 springs. 



In 1000 parts there were found : 



9. Petrifying quality of the Irawaddy.-^l formerly noticed the 

 petrifying qualities of the water of the river Irawaddy : I now saw 

 a strong proof of the rapidity with which it converts foreign bo- 

 dies into stone. The pioneers were ordered to remove a house, 

 which would have interfered with the defence of the stockade, if 

 the enemy had assailed it. Upon endeavouring to cut down the 

 massive teak-pillars on which it was raised, they found that the 

 edges of their hatchets were all turned. On examining into the 

 cause of this, they found that the pillars were petrified through- 

 out, though the house had only been built ten years, and the 



