2 Analysis of native Caustic Lime. [1816. 



deposits a considerable quantity. It contains also muriate of 

 lime and muriate of soda. The upper spring contains a little 

 carbonic acid gas, some sulphuretted hydrogen, and some 

 sulphate of soda. The following is the manner in which the 

 caustic lime is formed in this bath. The lower spring yields 

 a quantity of lime, but as this spring does not rise freely, but 

 oozes through the bottom of the bath, the lime forms a stra- 

 tum at the bottom of the lagune ; which stratum, absorbing 

 the carbonic acid gas of the water above, passes to the state of 

 a carbonate, and thus forms a defence to the lime, which is 

 continually depositing itself underneath, and prevents it losing 

 its causticity. In fact, the caustic lime is found enclosed 

 between the stratum of the carbonate of lime and the clayey 

 bottom of the laguna. 



Signor Taddei found the masses of caustic lime so large, 

 that he could not get them out but by breaking them into 

 pieces. He, however, succeeded in removing the whole of it : 

 and I, having visited the spot two months after, found small 

 incrustations of the same substance newly formed. 



ANALYSIS OF THE NATIVE CAUSTIC LIME. BY MR. FARADAY, ASSIST- 

 ANT IN THE LABORATORY OF THE ROYAL INSTITUTION. 



THIS substance came to England in a bottle filled up with 

 water, the atmospherical air being perfectly excluded. 



It is almost entirely soluble in muriatic acid without effer- 

 vescence, leaving nothing but a few light flocculi. The solu- 

 tion, when tested, was found to contain lime and iron. 



A clean uniform piece of the substance was dried, as much 

 as could be, by bibulous paper. A fragment of it being heated 

 red, lost 62*26 per cent, of water. 



The remainder of the original substance, weighing 188 

 grains, was dissolved in muriatic acid, and evaporated at a 

 high heat on the sand-bath, acid was again added, and the 

 evaporation repeated. Water was poured on it, and the silica 

 separated : when well washed, dried, and heated red, it 

 weighed 7*5 grains. 



The filtered solution was precipitated by carbonate of pot- 

 ash, and the precipitate boiled in solution of pure potash. 

 The solution was separated from the solid matter, neutralized 

 by sulphuric acid, and precipitated by carbonate of ammonia. 



