4 
THE PHARMACEUTICAL JOURNAL. 
[July 2, 1870. 
aside, crop up again. This week the daily papers report 
from Berlin that Liebreich has been employing as an 
anaesthetic the chloride of ethylidene—that is, the mono- 
chlorinated chloride of ethylo, with which Dr. Snow 
made us familiar nineteen years ago. Some of our most 
eminent surgeons, Mr. Bowman, Sir W. Fergusson, 
Mr. Henry Lee, and others, operated on patients imder 
this agent, and there was almost an unanimous opinion 
in favour of it, Snow himself being peculiarly impressed 
with its safety. The chloride when pure boils at a tem¬ 
perature a few degrees lower, and has a lower specific 
gravity and a lower vapour density than chloroform. 
It has a higher boiling-point, a higher specific gravity, 
and a higher vapour density than bichloride of methy¬ 
lene. Its composition is C 2 H 4 Cl 2 ; chloroform is C H Cl 3 ; 
and bichloride of methylene is CH 2 C1 2 . It is isomeric 
with Dutch liquid, but differs in boiling-point. The 
dose required to produce deep anaesthesia is about half 
an ounce. The notice of monochlorinated chloride of 
ethyle recalls to us the remembrance that our distin¬ 
guished countryman, Snow, was suddenly seized with 
his fatal illness while in the act of writing on this 
agent. He was drawing near to the conclusion of the 
chapter in his work which treats of this subject, when 
in the middle of a sentence he wrote his last word on the 
page—the word was “ exit.”—‘ Medical Times and Gazette ,’ 
June 1 \th, 1870. 
ON THE USE OF TINFOIL FOR PRESERVING SUB¬ 
STANCES LIABLE TO CHANGE ON EXPOSURE 
to,; AIR. 
BY ERNEST BATJDRIMONT. 
Tin reduced to thin sheets has for many years been 
employed for preserving a great number of substances 
from the action of air and moisture. The thin leaves 
(foil) of this metal are essentially repellent of moisture. 
When cemented to the surface of damp walls, they pro¬ 
tect the paperhangings which may be afterwards ap¬ 
plied, and they are in like manner used for lining the 
interior of boxes and drawers in which dried medicinal 
leaves and flowers are kept. It has long been the prac¬ 
tice to enclose chocolate in tinfoil, to prevent the fatty 
matter contained in it from soiling the paper which 
forms the outside wrapper; in the same way butter of 
cacao itself is preserved, and some sorts of sweetmeats, 
sausages, and cheese are among the articles similarly 
protected. Tobacco-pouches are lined with tinfoil to 
preserve the flavour and humidity of the tobacco. Cakes 
of opium are kept in a moist and uniform state by wrap¬ 
ping them in this material, and bisulphate of soda is 
kept in the same way, for use in making artificial Seltzer 
water with Briefs apparatus. Lastly, on account of the 
opacity of tinfoil to the rays of light, bottles are coated 
with it for the purpose of excluding light from vegetable 
substances which would be injured by its action. 
Notwithstanding the knowledge of all these facts, it 
might be said that the application of tinfoil for the pre¬ 
servation of substances liable to change is still rather 
limited, and there seemed to be a prospect of its admit¬ 
ting of a more general use than has hitherto been made 
of it. At the same time there was an absence of any 
precise experiments for the purpose of determining in a 
scientific manner the degree of impenetrability of tin- 
foil. Having been engaged for some time in the inves¬ 
tigation of this subject, I have obtained the following re¬ 
sults :— 
For many years past I have observed that cacao butter, 
which readily becomes rancid even when kept in bottles 
into which it has been introduced in the melted state, if 
the bottles be opened from time to time, does not imdergo 
the same change when moulded in tablets and wrapped 
in tinfoil. This fact, which was confirmed by many ob¬ 
servations, and could only be explained by assuming the 
impenetrability of tinfoil to atmospheric air, formed the 
starting-point for some experiments in the same direc¬ 
tion, which proved satisfactory. Thus, a piece of well- 
burned quicklime, enclosed in a double wrapper of tin- 
foil, was exposed in the atmosphere of the laboratory by 
the side of another similar piece which was exposed 
without protection. While the latter became slacked, 
that which was protected by the tinfoil, and weighed 
92-2 grams on the 1st of December, 1867, had only 
gained 3 decigrams in weight at the expiration of a 
month, and after being kept until the 2oth of March, 
1868, it had only increased to 94 grams. It had thus 
gained only l - 8 grams in four months. On being then 
taken out of its metallic envelope much heat was developed 
from absorption of moisture, and it fell into powder. 
Satisfied by this experiment of the efficacy of tinfoil 
for preserving bodies from the action of air and moisture, 
it seemed probable that substances the most susceptible 
of change might be kept in the same way. It was found 
that substances so deliquescent as chloride of calcium 
and liver of sulphur, and efflorescent salts such as car¬ 
bonate and sulphate of soda, remained almost unchanged 
when wrapped in tinfoil, increasing or diminishing only 
to a few thousandths of their weight in several weeks. 
Other experiments were made of a more precise cha¬ 
racter. It is well known that fresh lemons become 
rapidly dried and ultimately hard when exposed to the 
air, and that they also become perished and covered with 
mould. I had endeavoured to prevent this drying and 
moulding by placing the lemons in close vessels, in dry- 
air, in sand, and also in bran, but none of these methods 
proved efficacious. Thus, for example, in twenty-one 
days the lemons lost on an average, 17’33 per cent, of 
their weight in sand, and 17*13 per cent, in bran. Ex¬ 
periments were made for the purpose of ascertaining the 
efleet of enveloping the fruit in tinfoil, and also of coat¬ 
ing it with a fihn of collodion. Some of the fruit pre¬ 
pared in each way, and some unprepared, was weighed, 
exposed to the air, and again weighed at intervals of a 
month. This method was applied to lemons and oranges* 
and the following results were obtained:— 
1. The unprepared fruit became rapidly dried. In 
two months the lemons had lost 42 per cent, of their 
weight, while the oranges, in the same time, had lost 
only 26 per cent. 
2. Collodion, when applied to the fruit alone, exerted 
but a feeble preservative influence in retarding sponta¬ 
neous evaporation. In two months lemons coated with 
collodion had lost 29 per cent., and oranges 22’5 per cent. 
3. Tinfoil almost entirely prevents the drying of the 
fruit. In two months lemons lost only 1*58 per cent.* 
and in three months 3T6 per cent. In one case, indeed, 
the loss was only 0-92 per cent, during the longer 
period. Oranges lost about 5 per cent, in two months. 
On the removal of the metallic envelope, the fruit was- 
found to be as fresh and fragrant as when the experi¬ 
ments were commenced. These observations and experi¬ 
ments will tend to show the remarkable power of tinfoil 
in preserving substances enclosed in it from the influence 
of air and moisture derived from air, and may induce 
those who are interested in the subject to extend the 
application of this preservative means .—Journal de Thar - 
made et de Chimie. 
EFFECT OF BISULPHIDE OF CARBON ON WOOD. 
Bisulphide of carbon, according to Sidot, renders wood 
very sonorous, and makes it an excellent conductor of 
heat and electricity. Sidot passed vapours of bisulphide 
of carbon over pieces of wood in a porcelain tube, first 
in the cold, in order to expel the air, and then at high, 
temperature, the tube being slowly and gradually heated 
for an hour until it was red-hot. The various kinds of 
wood yield, by this treatment, a coal which is not sur¬ 
passed by the most sonorous substances known. Sidot 
made a bell of oak wood, and subjected it to this treat¬ 
ment with bisulphide of carbon. The sound it gave 
after the process compared favourably with that of a 
