972 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[June 7,1873. 
April | 
Old leaves 
Buds 
I Old leaves 
x a y | New leaves 
June, Old and new leaves 
July ... 
August 
September 
October 
November 
December 
100 
44 
110 
84 
125 
116 
110 
106 
100 
66 
O -- 
» 
Immediately after distillation. 
millig. 
After six months. 
millig. 
99 
28 May (new leaves) 
110 ... 
28 November ... 
. 108 
99 
28 June . 
. 84 ... 
28 December ... 
. 82 
99 
28 July . 
. 125 ... 
28 January, 1872 . 
. 118 
99 
28 August 
. 116 ... 
28 February 
. 110 
99 
28 September. 
. 110 ... 
28 March. 
. 110 
99 
28 October . 
. 106 ... 
28 April. 
. 98 
99 
28 November. 
. 100 ... 
28 May . 
. 92 
99 
28 December . 
66 ... 
28 June . 
. 50 
99 
The loss of acid 
is much 
more considerable when 
every month from the same bushes, which were very 
vigorous, and had been grown near Paris under the 
best possible conditions, so that the numbers ob¬ 
tained are comparable with each other. The experi¬ 
ments being made at the end of each month, the 
figures indicate the maximum quantity of prussic 
acid produced during that lapse of time. 
Examining attentively the preceding table, it will 
be remarked that the richness of the yield, instead of 
progressively increasing until the month of July, 
when it attains its maximum, presents in April and. 
May a remarkable irregularity. In fact, the figures 
fall from 100 to 76 ; but, on the other hand, having 
gathered the buds which appear just then and dis¬ 
tilled them, a distillate was obtained containing 100 
milligrams of acid. The question arises, What is the 
origin of so enormous a quantity of acid in organs 
which have only been a fortnight in existence ? It 
is not probable that the roots alone have contributed 
to its production: might it not be that the old leaves 
part with a portion of their elements to the new 
ones ? 
In May we see the same peculiarity renewed ; the 
proportion of acid is lower in the old leaves and 
higher in the new ones, which are then half deve¬ 
loped. In June a fresh anomaly presents itself ; the 
proportion of 84 milligrams appears at first surpris¬ 
ing, but this is explained if it be remembered that 
this product is obtained by distilling a mixture of 
equal parts of new and old leaves, and that the 84 
milligrams expresses nearly the mean between the 
numbers 110 and 44 obtained in the preceding 
month. In July the hydrocyanic acid amounts to 
125 ; from that time the proportion decreases, until 
at the end of December, after a cold of 20° C., it falls 
to 66. 
These experiments show the extreme variability of 
cherry-laurel water, according as it is prepared at 
different periods of the year; they also explain the 
different results obtained with the similar doses, to 
remedy which inconvenience the ‘ Codex ’ prescribes 
a strength of 50 milligrams. 
Cherry-laurel water, however, contains not only 
prussic acid in varying proportions, but also a vola¬ 
tile oil, which is a powerful poison, and of which the 
‘Codex ’ takes no account. 
The titrated water does not remain Tbng unaltered ; 
it is known that it loses gradually part of its acid. 
To ascertain the rate and proportion of this loss, a 
portion of each monthly distillation was put into a 
well-filled glass-stoppered bottle, and examined after 
keeping for six months, with the following results :— 
First titration. 
Immediately after distillation. 
28 January, 1871 
28 February . 
28 March. 
28 April (old leaves) 
Second titration. 
After six months. 
millig. 
millig. 
. 76 , 
... 28 July, 1871 ... 
... 68 
. 96 . 
... 28 August 
... 80 
. 100 . 
.. 28 September ... 
... 86 
76 . 
.. 28 October 
... 68 
First titration. 
Second titration. 
the distilled water is kept in bottles stopped with 
cork and not full. In order to ascertain these altera¬ 
tions, water distilled in February, 1871, and then 
containing 96 milligrams of acid, was examined dur¬ 
ing fifteen consecutive months, with the following 
results :— 
March 28, 1871 
April 28 
May 28 
June ... 
July ... 
August 
September 
October 
millig. 
86 
84 
80 
80 
80 
76 
74 
74 
November 28 
December 28 
January 28, 1872 
February 28 
March 28 . 
April 28 . 
May 28 . 
millig. 
74 
72 
72 
72 
72 
72 
72 
These figures show that from water kept in corked 
and only partially-filled bottles the loss of acid was 
at first very rapid, and afterwards became very slow, 
the strength remaining at 72 milligrams during six 
months. 
NOTES ON THE CULTIVATION AND PREPARATION 
OF LACTUCARIUM.* 
BY THOMAS FAIRGRIEVE. 
Lactucarium—a substance allied to opium in appear¬ 
ance and in physical and physiological properties—is pre¬ 
pared from the milky juice of various species of Lactuca. 
It was introduced into the pharmacy of this country by 
Dr. Duncan, Professor of Materia Medica, Edinburgh, in 
the early part of this century ; but it had been in use for 
some time previously in America, on the recommendation 
of Dr. Coxe, of Philadelphia. Professor Duncan em¬ 
ployed the garden lettuce as his source of lactucarium, 
and his process of preparation was as follows :—When 
the plant reached the flowering period, a portion of the 
stalk was cut off, and the milky juice which exuded was 
permitted to harden in the sun. On the following day 
this hardened juice was secured by cutting a thin slice off 
the stalk, and to this fresh wound a further quantity of 
juice flowed and again hardened, and so the process con¬ 
tinued from day to day till the plant was exhausted. The 
thin slices which bore the thickened juice were digested 
in spirit of wine till a solution of a certain degree of con¬ 
centration was obtained, which was then evaporated to a 
thick extract. 
Among later local cultivators were the late Dr. Young 
of Canonmills, and Mr. John Duncan, of Duncan, Flock- 
hart, and Co., who used the wild lettuce, Lactuca virosa, 
as the source from which they drew lactucarium. This 
plant is still found sparingly on Arthur’s Seat, near Dud- 
dingston, and is abundant on the rocks of Stirling castle 
and elsewhere. 
For the last sixteen years I have had from one to two 
acres under cultivation for the preparation of lactucarium. 
The plant employed is Lactuca virosa, var. montana, the 
seeds being sown in autumn, and the young plants planted 
out early in the following spring. The plant, under 
favourable circumstances, grows to a height of from 10 
‘Transactions and Proceedings of the Botanical So¬ 
ciety of Edinburgh,’ vol. xi. part 2. 
