CHLORAL. 
§ 207.] 
171 
The urine is evaporated to a syrup at the heat of the water-bath, 
and then strongly acidulated with sulphuric acid and repeatedly shaken 
out in a separating tube with a mixture of 3 vols. of ether and 1 vol. of 
alcohol. The ether-alcohol is separated and distilled off, the acid resi¬ 
due is neutralised with KHO, or potassic carbonate, and evaporated ; 
the dry mass is then taken up with 90 per cent, alcohol, the filtrate 
precipitated with ether, and the precipitate washed with ether and 
absolute alcohol. 
Next the precipitate is boiled with absolute alcohol and filtered 
hot. On cooling, the potassium salt of urochloral acid separates out in 
tufts of silky needles. The crystals are dried over sulphuric acid and 
again washed several times with absolute alcohol and ether to remove 
impurities. 
To obtain the free acid, the potassium salt is dissolved in a little 
water and acidulated with hydrochloric acid ; the liquid is then shaken 
out in a separating tube, with a mixture of 8 vols. of ether and 1 of 
alcohol. The ether-alcohol is distilled off, the residue treated with 
moist silver oxide until no further separation of silver chloride occurs, 
the silver chloride is separated by filtration, the soluble silver salt decom¬ 
posed by SH 2 , and the filtrate carefully evaporated to a syrup ; after a 
few hours, the acid crystallises in stars of needles. 
Urobutylchloral acid can be obtained in quite a similar way. 1 
§ 207. Separation of Chloral from Organic Matters. —It will be 
most convenient to place the organic fluid or pulped-up solid, mixed 
with water, in a retort, to acidify with tartaric acid, and to distil. 
Chloral hydrate distils over from a liquid acidified with tartaric 
acid ; to obtain the whole of the chloral requires distillation in a vacuum 
almost to dryness. 
The distillation will, unless there is also some partly decomposed 
chloral, not smell of chloroform, and yet give chloroform reactions. 
To identify it, to the distillate should be added a little burnt magnesia, 
and the distillate thus treated boiled for half an hour in a flask con¬ 
nected with an inverted condenser ; in this way the chloral hydrate is 
changed into chloroform 2 and magnesium formate— 
2CCl 3 CH(OH) 2 +MgO -> 2CHCI3+ (HCOO) 2 Mg-f H 2 0. 
The fluid may now be tested for formic acid : it will give a black precipi¬ 
tate with solution of silver nitrate— 
(HC00) a Mg+4AgN0,=4Ag+(N0 8 ) a +2C0 2 +2HN03. 
1 V. Mering u. Musculus, Ber., viii. 662 ; v. Mering, ibid., xv. 1019; E. Kulz, 
Ber., xv. 1538. 
2 Kipponberger (Arch. Pharm., ccxxxviii., 1900) states that when chloroform is 
distilled with an alkali some of it is decomposed, giving carbon monoxide and a 
chloride. The carbon monoxide may be estimated by means of palladium chloride. 
One part of metallic palladium*=112-6 parts of chloroform. 
