CHLORAL. 789 



from quicklime slaked and recently ignited, discontinuing the 

 distillation when the lime in the retort is no longer covered 

 by the liquid ; the product obtained is chloral, perfectly pure. 

 (Liebig). 



Chloral is a pretty fluid oleaginous liquid, colourless, greasy to 

 the touch, having a penetrating disagreeable odour which pro- 

 vokes tears 5 its taste is first oily and then caustic. Its density 

 is 1.502 at 64.4 (18 cent.), and it boils at 201.2 (94 cent.) 

 distilling without alteration ; the density of its vapour is very 

 nearly 5000, and its combining measure, 4 volumes (Dumas). 

 Chloral is miscible with alcohol and ether ; it dissolves, appa- 

 rently without alteration, sulphur, phosphorus and iodine, with 

 the aid of heat. 



Hydrate of chloral. Chloral is first obtained from alcohol in 

 the state of a hydrate, the water being derived from a reaction 

 of the nascent hydrochloric acid and alcohol, which gives rise to 

 water and chloride of ethyl. When pure chloral is brought in 

 contact with a small quantity of water, combination takes place 

 immediately on mixing the liquids, with evolution of heat, and 

 in a few seconds the compound is deposited as a crystalline 

 mass, composed of needles, which re-dissolve in a larger quan- 

 tity of water. By evaporation of the solution in vacuo, the 

 compound is obtained in large rhombohedral crystals, which 

 contain 2 atoms of water. The solution of the hydrate of 

 chloral is neutral, and has no action on red oxide of mercury ; 

 the dry hydrate may be distilled without change. 



Insoluble chloral. Like aldehyde pure chloral cannot be kept 

 long without alteration. It gradually passes into a solid mass 

 resembling porcelain, without change of weight, and equally 

 whether contained in vessels which are hermetically sealed or 

 open. This mass is not dissolved by water, but when placed 

 in contact with a very small quantity of water, it slowly changes 

 into the crystalline hydrated chloral, which dissolves at once 

 when a large quantity of water is added to it. Insoluble chloral 

 is modified by contact with sulphuric acid, and somewhat altered 

 in composition ; w r hen washed with water it loses a little hydro- 

 chloric acid, and acquires some water. The formula assigned to 

 modified insoluble chloral is C 12 H 4 C1 8 O 7 : which is 3 atoms of 

 chloral, minus 1 atom of hydrochloric acid plus 2 atoms of 

 water. 



