January 7, 1871.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
MI 
CHLORAL. 
Hydrate—Alcoholate—Tests—Therapeutical 
Value—Pharmaceutical Preparations.* * * § 
BY ALFRED H. MASON. 
The principal object of this paper is to show that 
the hydrate of chloral of commerce is not all pure 
hydrate of chloral, but that other compounds have 
been put upon the market. I have examined 
samples, obtained from different sources, varying 
very seriously in the proportion of chloroform they 
produce upon decomposition with alkaline reagents, 
and I feel it a moral duty to pharmaceutists to ad¬ 
vise them of these facts. When it is considered 
that one agent alone in London has disposed of 
twenty-two thousand pounds’ weight f during the 
past twelve months, it is certainly high time for us 
to be alive to the necessity of dispensing a gua¬ 
ranteed article. 
Chloral, C 2 C] 3 HO, is formed by the prolonged 
action of chlorine upon absolute alcohol. J To pre¬ 
pare it, the current of chlorine must be kept up as 
long as hydrochloric acid gas continues to escape, 
and the product is to be agitated with three times its 
volume of concentrated sulphuric acid. On gently 
warming this mixture in a water-batli, the impure 
chloral separates as an oily liquid, which floats on 
the surface of the acid; it is purified by distillation 
from fresh sulphuric acid, and afterwards from a 
small quantity of quicklime, which must be kept 
completely covered by the liquid until the end of the 
operation. The chemical reactions which take place 
in its formation were described in a valuable paper 
by Mr. Henry Sugden Evans, of London, last session. 
Chloral is a thin, oily, colourless liquid, of pecu¬ 
liar and penetrating odour, which excites tears, and 
it has but little taste. 
Liebreich says,§ if chloral be left in contact with 
concentrated sulphuric acid, it is transformed into 
polymeric insoluble chloral; this body is more easily 
purified, since it is not soluble in alkalies or acids, 
and it may be treated a long time with these sub¬ 
stances without decomposing. Warm this insoluble 
chloral, and it converts itself into soluble chloral. 
The sp. gr. of soluble chloral is 1*502. By degrees 
it thickens, and is sometimes transformed suddenly 
into soluble chloral evolving a large amount of heat. 
When we mix anhydrous chloral with water, we 
obta in in a short time acicular crystals of hydrate 
of chloral, this body being distinguished from ordi¬ 
nary chloral by containing one molecule of water. 
Its formula is C 2 Cl 3 II0+ H 2 O. 
This method is the one alone authorized by Dr. 
Liebreich, of Berlin, || who took out a patent in July, 
1869, for the sole use for anaesthetic purposes of 
chloral, hydrate of chloral, and trichloroacetic acid, 
(CjHCls'Og). 
The physiological and therapeutical experiments 
made by Liebreich led to the introduction of this 
product as a medicinal agent, and since he has pub- 
* Read at a meeting of the Liverpool Chemists’ Associa¬ 
tion, held December 22nd, 1870. 
t Dais includes both kinds of hydrate of chloral, as distin¬ 
guished novo by the agents themselves,—guaranteed and un¬ 
guaranteed. 6 
X Downes’ ‘ Manual of Chemistry,’ p. 813. 1868. 
§ ‘ L’Hydrate de Chloral,’ O. Liebreich, 1870, p. 15. 
I Idem. 
Third Series, No. 28. 
lislied liis formula,* with the results of his experi¬ 
ments, I think we should fix upon his method as the 
officinal one. The superiority of the hydrate of 
chloral manufactured under liis supervision I shall 
prove to you (i. e., if the larger proportion o f chloro¬ 
form produced In/ alkaline reagents from the chloral 
compound employed is to be the test, which is, I 
think, self-evident). He tells us that numerous ex¬ 
periments show that this method is far the most 
trustworthy. 
Chloral is obtained in other ways ; for instance, 
by the method of Stiedeler, from starch, by distilla¬ 
tion with hydrochloric acid and dioxide of manga¬ 
nese, Jformic acid, carbonic acid and other bodies 
accompanying it; but Liebreich states he has made 
experiments with this preparation and finds it is not 
to be depended upon in its action, from the great 
difficult}" of preventing the formation of other com¬ 
pounds, especially chlorides of carbon, which serve 
to contaminate the chloral and render its adminis¬ 
tration dangerous. 
It was contended by M. J. Personnel that the 
hydrate of chloral described by M. Roussin as pure, 
was nothing more than a compound of chloral and 
alcohol. Differences being observed in the physical 
properties of the preparation made by Liebreich and 
that made by Roussin, it was found that they were 
two entirely distinct compounds, which was fully 
confirmed by an appeal to analysis. Theoretically, 
hydrate of chloral should contain 64*35 per cent, of 
chlorine. M. Personne found that the preparation 
he had made contained 63*79 per cent., whilst a 
sample of that made by M. Roussin yielded only 
51*89 per cent. Following this indication, Personne 
endeavoured to ascertain by experiments whether 
the hydrate of chloral prepared by Roussin did, or 
did not, contain alcohol. The results were very 
satisfactory in proving the presence of this com¬ 
pound. Further, by combining anhydrous chloral 
and absolute alcohol in proper proportions, Per¬ 
sonne was enabled to prepare synthetically a sub¬ 
stance having properties entirely similar to those 
of the supposed hydrate of chloral prepared by 
Roussin. 
It is this preparation, alcoholate of chloral, repre¬ 
sented by C 2 C1 3 H0 + C 2 H 6 0, that we meet with 
in commerce, also hydrated alcoholate of chloral, 
which are not to be trusted as therapeutic agents 
according to the system laid down by Liebreich. 
At a meeting of the Pharmaceutical Society, Mr. 
John Williams suggested that an alkaline reagent 
would show the percentage of chloroform the chloral 
preparation would produce. Mr. Charles Umney 
has also made some very valuable experiments, and 
instituted what is now known to pharmacists as 
“ the ammonia process ” for testing hydrate of 
chloral. The mode of operating, and the results of 
his experiments, are published in the Pharmaceu¬ 
tical Journal. 
I find that hydrate of chloral is insoluble in cold 
chloroform, tetrachloride of carbon, turpentine and 
bisulphide of carbon, but on the application of heat, 
solution is effected. The hydrate is, however, per¬ 
fectly soluble in cold water, ether (*735) and absolute 
alcohol (*805); after the application of heat, and 
upon cooling, the hydrate separates in beautiful 
crystals, generally needles, but from bisulphide of 
# < L’Hydrate de Chloral.’ Oscar Liebreich. 
f Journal de Pharmacie et de Chimie. 
