TIIE PHARMACEUTICAL JOURNAL AXE TRANSACTIONS. 
[May 20, 1871. 
C24 
mixed with f 5ij of water, for two or three days ; 
then percolate with water till 8 fluid ounces of liquid 
are obtained, in which dissolve the sugar. 
This syrup is quite pleasant to the taste, and can 
be taken alone or mixed with water; it has been 
prescribed for several years by Dr. Ludlow, of Phil¬ 
adelphia, with decided benefit in cases of rheuma¬ 
tism, and can be given for a long period without 
exciting disgust. 
The quantity of solution of potash may be doubled 
without rendering the syrup unpalatable, and thus 
would increase the amount of guaiac dissolved.— 
Proc. Amer. Pharm. Assoc. 1870. 
CHEMICAL NOTES TO THE PHARMACOPOEIA. 
BY WILLIAM A. TILDEN, B.SC. LOND. 
DEMONSTRATOR OF PRACTICAL CHEMISTRY TO THE 
PHARMACEUTICAL SOCIETY. 
Glycertnum, C 3 H s 0 3 or C 3 H 5 (PIO) 3 .—Glycerine 
is obtained from fats or fixed oils by one or other of 
several processes:— 
1. In the manufacture of emp. plumbi (q. v.). The 
acfueous solution, separated from the plaster, is, if 
necessary, treated with a little sulphuretted hydro¬ 
gen, to remove from it a small quantity of oxide of 
lead retained in solution. The precipitated sulphide 
of lead is removed by subsidence, and the clear 
liquid evaporated to a syrup. 
2. By throwing steam previously heated to about 
500° F. into heated fat contained in a boiler a distil¬ 
late is obtained, which separates on standing into 
an aqueous solution of pure glycerine and an oily 
layer consisting of the acids of the fat. (Price’s 
Glycerine.) Suppose stearine to have been the ma¬ 
terial employed:— 
C 3 H 5 3C 13 H 35 0 2 + 3H.H0 
Stearine. Water. 
= C 3 H 5 3 H O + 3 H C, ,H„ 0 2 . 
Glycerine. Stearic acid. 
3. The spent leys from which hard soap has been 
separated contain a quantity of glycerine. Thus— 
C 3 H 5 3 C 13 H 33 0 2 + 3 Na H O 
Oleine. Hydrate of Sodium. 
= C 3 H 5 3 H 0 + 3 Na C ls H 33 0 2 . 
Glycerine. Oleate of sodium! 
. Tllls is now recovered in some works by neutra¬ 
lizing the alkaline liquid by an acid, evaporating to 
a low bulk, and distilling the residue in a current of 
steam. 
Pure glycerine should be colourless and odour¬ 
less, sp. gr. 1-25 (B.P.). The glycerine of the Phar¬ 
macopoeia contains a small percentage of water. 
Much of the glycerine of commerce, particularly the 
foreign, which is generally made by the lead-plaster 
process, contains chlorides of sodium and calcium, 
and will not therefore form a clear mixture with 
nitrate of silver.. Glycerine is readily oxidizable, 
and is therefore incompatible with such agents as 
permanganates. It is slightly volatile at the boil¬ 
ing-point of water, but cannot be distilled in the 
ordinary way without much decomposition, intensely 
irritating vapours of acrolein being evolved, it 
may, however, be distilled without change in a cur¬ 
rent of superheated steam or in a partial vacuum. 
The vapour of glycerine is inflammable. Glycerine, 
as shown by the formula C 3 H s (HO) 3 , is the hydrate 
of a trivalent radicle. The action of acids upon it 
gives rise to the formation of salts (of 'which the fats 
are examples) analogous to the compound ethers 
formed from ordinary alcohol,—the difference be¬ 
tween them being that, whereas ordinary alcohol is 
the hydrate of a univalent hydrocarbon, it can form 
with a monobasic acid only one such compound, as 
acetic ether, C 3 H 5 .C 2 H 3 0 2 . 
Glycerine, being the hydrate of a tn valent hydro¬ 
carbon, may form with such an acid as acetic or 
stearic three different compounds. 
Glycerine.(C 3 H 5 ) , "(HO) 3 . 
Glyceryl mono-acetate . (0 3 H 5 ) , "(HO) 2 O 2 H 3 O !! . 
,, di-acetate . . (C 3 H 5 )"'(H0)(C 2 H 3 0 2 ) 2 . 
tri-acetate . . (C 3 H 5 V ,, (C 2 H 3 0 2 \ v 
„ mono-stearate. (C 3 H 5 )" , (H0) 2 C 13 H 35 0 2 . 
,, di-stearate . . (C 3 H 5 ) W (HO) (C 18 H 35 0 2 ) 2 . 
„ tri-stearate . (C 3 H 5 ) ,,/ (C 13 H 33 0 2 ) 3 . 
(Common stearine.) 
The relation of glycerine to oil of mustard is in¬ 
teresting. When distilled with biniodide of phos¬ 
phorus, it yields the iodide of a radicle containing 
the same elements as glyceryl, but univalent. 
2 C 3 H 5 3 H 0 + P 2 1 4 
= 2 C 3 H 5 1 + 2 P H O (H 0) 2 -f I 2 . 
Iodide of aliyl. Phosphorous acid. 
And this iodide, digested with sulphocyanide of 
potassium, yields mustard-oil and iodide of potas¬ 
sium. 
C 3 H 5 1 + K N C S = KI + (C 3 H 5 ) N (C S)". 
Mustard oil. 
Hydrargyri Iodidum Rcbrum. 
Four parts of percliloride of mercury are dissolved 
in boiling distilled water and mixed with live parts 
of iodide of potassium similarly dissolved. The 
scarlet precipitate is collected, washed and dried at 
212 °. 
HgCl 2 + 2KI = Hgl 2 + 2KC1. 
In the process of precipitating the iodine, a salmon- 
coloured precipitate is first thrown down; this is a 
compound of iodide and chloride, which is changed 
by the further addition of iodide of potassium into 
pure iodide. An excess of iodide of potassium causes 
the precipitate to disappear. 
It may also be prepared by rubbing together in a 
mortar mercury and iodine in the proportions repre¬ 
sented by the formula. 
Urr I — H°T 
xx © I x 2 — xx o x 2 
200 -f 127x2 451 
Bed iodide of mercury is almost absolutely insolu¬ 
ble in water, but is slightly soluble in alcohol, freely 
so in ether, and in a solution of iodide of potassium, 
forming in the last case a double salt, HgI 2 KI. 
It is also dissolved by hydrochloric acid, common 
salt, sal ammoniac and by a solution of corrosive 
sublimate, in which case it gives a double iodo-chlo¬ 
ride, Hg I 2 2 Hg Cl 2 . 
One of its most curious properties is that of chang¬ 
ing into a yellow allotropic modification when heated 
gently. When sublimed it forms magnificent thin 
prismatic crystals, which, whilst warm and undis¬ 
turbed, are yellow, but resume the red colour spon¬ 
taneously after a time, or immediately on being 
rubbed. 
