February 4,1871.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS 
623 
CHEMICAL NOTES TO THE PHARMACOPOEIA. 
BY WILLIAM A. TILDEX, B.SC. LOND. 
DEMONSTRATOR OF PRACTICAL CHEMISTRY TO THE 
PHARMACEUTICAL SOCIETY. 
necessary, but prevents irregularities in the decom¬ 
position. 
The foregoing explanation of the reaction is ren¬ 
dered probable by what we know of chloral. This 
body in the form of hydrate is now familiar to every 
one. It is made by passing dry chlorine gas into 
absolute alcohol. 
Cerii Oxalas. —CeC 2 0 4 3H 2 0. 
[§ A salt which may be obtained as a precipitate 
by adding solution of oxalate of ammonia to a solu¬ 
ble salt of cerium.] The chloride may be employed. 
[§ A white granular powder, insoluble in water, 
decomposed at a dull red heat into a reddish-brown 
powder (a mixture of CeO and Ce 2 0 3 ), which dis¬ 
solves completely and without effervescence in boil¬ 
ing hydrochloric acid, and the resulting solution gives 
with solution of sulphate of potash a white crystal¬ 
line precipitate (of double sulphate of cerium and 
potassium). If the salt be boiled with solution of 
potash and filtered, the filtrate is not affected by 
solution of chloride of ammonium (showing the ab¬ 
sence of alumina) ; but when supersaturated with 
acetic acid it gives with chloride of calcium a white 
precipitate (oxalate of calcium) which is soluble in 
hydrochloric acid. Ten grains when incinerated lose 
52 grains in weight.] That is, a residue of oxide 
weighing 4*8 grains is left. If it consisted solely of 
cerous oxide Ce O, the residue would weigh 4'G grains, 
but a small quantity of peroxide is always formed; 
thus the slight increase in weight is accounted for. 
Chlorofoiimum.—C H Cl 3 . 
Into a capacious still is introduced a quantity of 
rectified spirit diluted with much water. Heat is 
applied, and when the temperature reaches 100° F., 
a mixture of slaked lime and chlorinated lime is 
added. When the mixture commences to froth, the 
fire is removed, and in a short time the process is 
complete. There is no necessity for continuing the 
application of heat any length of time, as the whole 
of the chloroform comes over at the commencement. 
The product is purified by washing it first with 
water, then with strong sulphuric acid; finally it is 
dried and purified from traces of acid by redistilling 
it from a mixture of chloride of calcium and dry 
slaked lime. 
Chlorinated lime is an agent capable of acting by 
supplying either oxygen or chlorine. Thus it may 
split in a manner represented by either of the two 
folio whig equations — 
CaC10Cl=CaC] 2 + O. 
or Ca Cl 0 Cl=Ca 0 + CL. 
In the production of chloroform it acts both ways. 
First the alcohol is believed to lose hydrogen and 
become converted into aldehyd. 
C 2 H 6 0 + 0=C 2 'H 4 0 + H 2 0. 
Then the aldehyd is acted upon by the chlorine from 
another portion giving chloral, which in its turn is 
decomposed by the lime into chloroform and calcic 
formate. 
C ? H 4 0+ 3C1 2 = C 2 HC1 3 0 + 3HC1. 
Aldehyd. Chloral. 
2 CoHCl 8 0 + Ca2HO = Ca2CH0 2 + 2CHC1 3 . 
Chloral. Formate of “ Chloroform. 
Calcium. 
The chloroform distils over, the formate remains 
mixed with the excess of lime and water in the re¬ 
tort. The slaked lime employed is not absolutely 
C 2 H 6 0 + 4 Cl 2 = C 2 H Cl 3 O + 5 H Cl. 
Alcohol. Chloral. 
When treated by alkalies it breaks up as shown in 
the equation already given. Ammonia is employed 
when it is desired to test it quantitatively. By the 
amount of chloroform produced, the proportion of 
real chloral present can easily be calculated. 
The sulphuric acid employed to purify chloroform 
must be free from all traces of oxides of nitrogen; 
for it has been shown that the apparently sponta¬ 
neous decomposition to which chloroform is some¬ 
times subject is to be attributed to contamination of 
this kind. 
The best indication that chloroform is free from 
noxious impurities is that it evaporates from the 
hand without leaving a residue or odour of any kind. 
Admixture of spirit would be indicated by the specific 
gravity. 
Chloroform is still sometimes called percliloride of 
formyl, in accordance with the supposition that it is 
a chloride of an assumed radicle (C H/", formyl, the 
existence of which is doubtful. All the different 
views which may be held respecting the constitution 
of chloroform in reality amount to one and the same 
thing; in this bod}' we have an atom of quadrivalent 
carbon united with and saturated by the four univa¬ 
lent atoms, one of hydrogen and three of chlorine. 
By dissolving chloroform in spirit of wine acidu¬ 
lated with hydrochloric acid, to which a few drops of 
percliloride of platinum have been added, and digest¬ 
ing the mixture upon granulated zinc in a flask to 
which a Liebig’s condenser is attached, dicliloride of 
methylene is gradually produced, and distils over. 
CHClg + H 2 = CH 2 C1 2 + HC1. 
Dicliloride of methylene has been tried with some 
success as an anaesthetic, but its production in quan¬ 
tity is uncertain and difficult. 
By submitting chloroform to the action of excess 
of chlorine, a liquid, tetrachloride (formerly called 
bichloride) of carbon, C Cl 4 . is produced. 
These bodies form part of a series which well illus¬ 
trates the law of “ substitution;” for they may all be 
formed simultaneously by the action of chlorine upon 
marsh gas,—the atoms of hydrogen in that body 
being one after the other replaced by equivalent 
chlorine atoms. 
Marsh gas or methyl hydride . . 
Methyl chloride or methyl-hydro¬ 
chloric ether. 
Methylene dicliloride 
Chloroform. 
Carbon tetrachloride. 
C 
HHHH 
C 
HIIHC? 
C 
Ithcici 
c 
HCICICI 
c 
cicicTci 
