June 7, 1873.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
971 
.sation and freezing of moisture from the surrounding 
air. 
The last process to he mentioned is patented by 
Mr. Ruck, and is to be worked by “The New Gas 
Company, Limited.” Superheated steam is passed 
over a mixture of coke and metallic iron at a high 
temperature. A mixture of hydrogen, carbonic oxide, 
and carbonic anhydride is thus obtained, which is 
called “ heating gas,” and is intended to be used for 
heating purposes without further treatment, except 
passing over oxide of iron to remove traces of sul¬ 
phuretted hydrogen. In this state it is said to con¬ 
sist of about 58 per cent, of hydrogen, 30 per cent, of 
carbonic oxide, and 12 per cent, of carbonic anhydride. 
To convert it into illuminating gas it is made to 
bubble through light petroleum spirit of a specific 
gravity of about 0'680, in a similar manner to the 
“air gas.” 
This process has been advocated by some persons 
as utilizing what is called “the exhaustless store of 
heating power that lies ready to hand in water.” But 
it will be clearly seen that this involves the same 
mistake as that in the first two processes which we 
have considered. For, although the hydrogen in the 
gas does come from the water introduced into the re¬ 
tort as steam, yet it is obtained at the expense of the 
coke and iron over which it passes. So that the heat 
is not derived from the water, but from the coke or 
iron ; and the real question at issue is again, whether 
this is an economical method of obtaining heat from 
coal or coke. 
It has been stated that the combustion of one ton 
of coke in the retorts, and of two tons externally in 
the furnace, will yield 133,000 cubic feet of gas, and 
that this will be increased in volume to 165,000 cubic 
feet by passing through the petroleum ; the cost of 
the heating gas being estimated at Id. per 1000 cubic 
feet, and of the illuminating variety Is. 8 d. In this 
estimate there is apparently no account taken of the 
cost of the iron oxidized (i. e. consumed) in the retorts, 
although this must be a point of some importance, 
especially as scrap iron is used, which is rather costly. 
The four questions as to cost and storage of petro¬ 
leum, uniformity of illuminating power, and practi¬ 
cability of distribution through pipes, all apply again 
here. It is true that certain advantages are claimed 
for this gas in regard to the last particular, but we 
fear these will not, for the most part, bear investiga¬ 
tion. It is said that this product is a true gas, and 
that therefore it forms a more intimate union with 
the petroleum than air does. But it is evident that 
this is using the word “gas” ambiguously ; for although 
air is not in the ordinary sense a combustible gas, yet 
it is quite as truly a gas as the mixture of hydrogen, 
carbonic oxide, and carbonic anhydride in question. 
The petroleum vapour forms precisely similar mix¬ 
tures in both cases ; and although the mixture 
would become homogeneous rather more rapidly in 
the “new gas” process than in the “air gas,” yet the 
difference of time would be very slight, and, the 
mixture once made, the result would be as perma¬ 
nent in the one case as in the other. A real advan¬ 
tage in favour of the new gas is its low specific 
gravity—little more than "half that of air—so that its 
passage through pipes would be effected with less 
mechanical difficulty. 
On the other hand, we must point out two disad¬ 
vantages. The first of these seems to be inseparable 
from the process, namely, the large percentage of 
carbonic oxide which the gas contains. It is a very 
serious matter to introduce into our dwelling-houses 
a gas containing 30 per cent, of so active and well 
known a poison as carbonic oxide. Of course, if we 
could be sure that it would all be burnt, no objection 
could be raised, but gas fittings are by no means 
always perfect, and serious escapes frequently occur. 
As this gas has decidedly less odour than common 
coal gas, the facility for detection in such cases would 
be proportionally diminished. The other disadvan¬ 
tage is the presence of so much as 12 per cent, 
of carbonic anhydride As this could be removed 
with little difficulty, we are rather surprised to see 
that the directors do not propose to do so ; for it has 
a powerfully deteriorating effect upon the illuminat¬ 
ing power. Mr. Barlow found that 1 per cent, of it 
in common coal gas caused a loss of 7 per cent, of 
light, and even if the New Gas Company is able by 
an increased quantity of petroleum to overcome this, 
it is likely that the removal of the carbonic anhydride 
would be much cheaper, and the purified gas would 
be less injurious to the atmosphere of the rooms in 
which it was burnt. 
CHERRY-LAUREL WATER.* 
BY M. LEGER. 
The leaves of the cherry-laurel yield to distillation 
a volatile oil and prussic acid in variable proportions, 
dependent upon the time of year at which they are 
gathered. According to Brugnatelli, the most is ob¬ 
tained in the spring-time. Soubeiran, on the other 
hand, affirms that in the neighbourhood of Paris the 
leaves afford the richest yield in July and August. 
Garot states that in the month of April the leaves 
give, upon boiling them with water, a large quantity 
of vegetable wax and no volatile oil, whilst in August 
the contrary is the case. This observation the author 
has found to be completely erroneous, as he has ob¬ 
tained both products simultaneously at all seasons of 
the year. There being therefore considerable discre¬ 
pancy between various authorities upon this subject, 
the author, in an investigation lasting more than a 
year, has sought to elucidate it, by ascertaining what 
period of the year corresponded with the largest 
quantity of hydrocyanic acid, leaving for future in¬ 
quiry the estimation of the volatile oil. The method 
employed was that of Buignet. 
The essence and the prussic acid, as has been 
shown by Lepage, preexist in the leaves of the 
cherry-laurel, being developed there during vegeta¬ 
tion by the action of synaptase upon amygdalin, two 
substances which Robiquet had already found in 
almonds, and of which Wicke and Lepage had de¬ 
monstrated the existence in the cherry-laurel. When, 
therefore, the leaves are distilled with water there 
is no chemical action produced, as in the case of 
almonds ; the object of the distillation is simply to 
separate the products already elaborated by Nature. 
The author distilled each month 1 kilogram of leaves 
with sufficient water to obtain 1500 grams of product 
(‘ Codex ’); the various distillates, containing all 
the essence and acid, were immediately titrated, and 
the following table indicates the results obtained 
during one year :— 
January . 76 milligrams. 
February . 96 „ 
* Abstracted from the ‘ Repertoire de Pharmacie,’ vol. i. 
new series, p. 269. 
