1820.] and Examination of the Chemical Vroperlies of hilhiu. 345 



in less pure specimens of a pale rose red colour, which I gene- 

 rally laid aside as not sufficiently pure for my purpose. 



Chemical Properties of Lithia. 



The greater number of these properties are already known 

 from the experiments of Arfvedson and Vauquelin. 1 have 

 extended my researches somewhat further ; and I have some- 

 times obtained results a little different from these chemists. 



Caustic Lithia. — Into a solution of sulphate of lithia in a glass 

 tube furnished with a glass stopper baiy tes water was dropped as 

 long as a precipitate continued to fall. Much patience was 

 necessary to obtain a liquid neither precipitated by barytes 

 water, nor by sulphuric acid. The solution of caustic lithia was 

 filtered as rapidly as possible into a tubulated retort, to which a 

 receiver had been previously adjusted. The solution was then 

 distilled by placing the retort on a sandbath. When the liquid 

 in the retort became very concentrated, a white powder sepa- 

 rated, and likewise some small granular crystals whose form, 

 could not be determined. These fell while the liquid was still 

 hot. 



The retort was now taken from the fire and placed in a cellar 

 without exposing the liquid which it contained to the action of 

 the air. Neither the powder nor the small crystals appeared to 

 increase during the cooling. Hence it would appear that caustic 

 lithia is not much more soluble in hot than in cold water. The 

 very concentrated solution was evaporated to dryness in a plati- 

 num crucible by means of a spirit lamp. By this means dry 

 caustic lithia was obtained in which acids could detect no trace 

 of carbonic acid. 



A portion of this matter exposed to heat in a platiniun crucible 

 melted before it became sensibly red-hot. The fused mass was 

 transparent. When allowed to cool in the open air so as to 

 absorb carbonic acid, it became opaque. 



Caustic hthia has a very sharp burning taste. It destroys the 

 cuticle of the tongue, like potash, and seems to me in point of 

 causticity very nearly to equal tiiat alkali. It does not dissolve 

 with great facility in water. But the small quantity with which 

 I was provided did not allow me to determine the exact solubility 

 of it in that liquid. It appears, as has been already observed, 

 not to be much more soluble in hot than in cold water. In this 

 respect it has an analogy with lime. Heat is evolved during its 

 solution in water. 



When exposed to the air, it does not attract moisture, but 

 aV)sorbs carbonic acid, and becomes opaque. When exposed 

 for an hour to a wiiite heat in a covered platinum crucible, its 

 bulk does net appear to be diminished ; but it has absorbed a 

 quantity of carbonic acid. 



It dissolves <mly in small quantity in alcohol of the specific 

 gravity 0-86. When weak alcohol is added to an aqueous sola- 



