e into absolute alcohol; the
latter must be cooled at first, but towards the end of the operation has
to be heated nearly to boiling. The alcohol is converted finally into a
syrupy fluid, from which chloral is procured by treatment with sulphuric
acid (see P. Fritsch, _Ann._, 1894, pp. 279, 288). The crude chloral is
distilled over lime, and is purified by further treatment with sulphuric
acid, and by redistillation. A mixture of starch or sugar with manganese
peroxide and hydrochloric acid may be employed instead of alcohol and
chlorine for the manufacture of chloral (A. Staedeler, _Ann. Ch.
Pharm._, 1847, 61, p. 101). An isomer of chloral, _parachloralide_, is
made by passing excess of dry chlorine into absolute methyl alcohol.

_Chloral hydrate_, CCl3.CH(OH)2, forms oblique, often very short,
rhombic prisms. The crystals are perfectly transparent, only slightly
odorous, free from powder, and dry to the touch, and do not become
white by exposure. The melting-point of pure chloral hydrate is 57 deg.,
the boiling-point 96-98 deg. C. When heated with sulphuric acid it is
converted into anhydrous chloral and _chloralide_, C6H2Cl6O3. When
mixed with water, chloral hydrate causes a considerable degree of
cold; and, as with camphor, small fragments of it placed on the
surface of water exhibit gyratory movements. Chloral hydrate does not
restore the colour to a solution of fuchsine which has been
decolorized by sulphurous acid, and so one must assume that the water
present is combined in the molecular condition (V. Meyer, _Ber._,
1880, 13, p. 2343). Chloral may be estimated by distilling the hydrate
with milk of lime and measuring the volume of chloroform produced
(C.H. Wood, _Pharm. Journ._, (3) 1, p. 703), or by hydrolysis with a
known volume of standard alkali and back titration with standard acid
(V. Meyer, _Ber._, 1873, 6, p. 600). Chloral hydrate has the property
of checking the decomposition of a great number of albuminous
substances, such as milk and meat; and a mixture of it with glycerin,
according to J. Personne, is suitable for the preservation of
anatomical preparations. When heated with concentrated glycerin to a
temperature of 110 deg. to 230 deg. C, chloral hydrate yields chloroform,
CHCl3, and allyl formate, HCO(OC3H5).

_Pharmacology and Therapeutics._--The breaking up of chloral hydrate,
in the presence of alkalis, with the production of chloroform and
fo