Hjfdrcrted Chloride of Aluminium. '253 



Hydrogen being taken as the unit, and oxygen called 8, the com- 

 position would be 



Oxygen. 12.0000=1^ atoms. 



Aluminium, 10.5504 = 1 atom. 



Alumina, 2'2.5501 



II. Hydrated Chloride of Aluminium. 



(A) A phial containing chloride of aluminium was closely cork- 

 ed ; but this did not entirely exclude the access of moisture, and du- 

 ring three years that it had been thus enclosed, enough water had 

 been absorbed to cause a portion to deliquesce into a thick, oily 

 liquid of a deep lemon yellow color. 



The liquid covered a portion of the solid yellow chloride, which 

 is probably the hydrated chloride mentioned by Berzelius in his 

 Traite de Chimie. The hydrated liquid chloride does not hiss in 

 water like the anhydrous chloride, but sinks to the bottom without 

 easily mixing. When mixed with water and agitated to make them 

 unite, the color disappears and the solution becomes perfectly color- 

 less and transparent. 



A drop of the Hquid chloride when heated in a small bulb with a 

 capillary neck, gave ofFno water separately, but only in combination 

 with muriatic acid, and alumina remained in the bulb. 



Analysis. — A quantity of the liquid hydrated chloride of alumi- 

 nium weishins; 129 crrains, was mingled with water enough to make 

 the solution rather dilute. Ammonia was added to the solution and 

 a gelatinous precipitate of alumina was thrown down. After stand- 

 ing some hours, the supernatant liquid, which was perfectly limpid, 

 was drawn off, and pure water added to wash the precipitate. The 

 clear liquid was again drawn off, and the precipitate repeatedly wash- 

 ed in the same way, being well stirred with a glass rod, each time 

 that water was added. The precipitate was thrown upon a double 

 filter of equal weights, the same precautions being used as in the 

 preceding analysis, and washed until there was no longer a trace of 

 cloudiness by adding nitrate of silver to the filtered water. The pre- 

 cipitated hydrate of alumina was dried on the sandbath, very gradu- 

 ally, for several days, that the drying might be uniform through the 

 mass and the filter was loosely covered by paper to prevent the ac- 

 cess of dust. 



