1022 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[June 21, 1875 
specific gravities 0719, 0S5, and 1*272, the vapour ten¬ 
sions, and consequently the boiling-points, follow just the 
contrary order, and the body possessing the greatest den¬ 
sity is really the most volatile. The vapour tension of 
alcohol, at ordinary temperatures, viz., about 15° C., is 
equal to the depression of the mercurial column to the 
extent of 30mm., the boiling-point of alcohol, being 79° C. ; 
the vapour tension of benzole, in the same manner, is 55, 
and the boiling-point of the liquid 78° C., and of bisulphide 
of carbon as high as 250, with a boiling-point of 48° C. ; 
low specific gravity is, therefore, not always coupled with 
low boiling-point and great volatility. 
A law was enunciated by Dalton, which, though since 
proved to be only approximately true, nevertheless enables 
us to obtain a rough idea of the vapour tension of any 
liquid if we know its boiling-point, which was this :— 
“ The vapours of different liquids have equal tensions at 
temperatures equally removed from their boiling-points.” 
Thus, the boiling-point of alcohol being 79°, the vapour 
tension of alcohol at 50 0 ought to be equal to the vapour 
tension of water (with a boiling-point of 100° C.) at 71°, 
which is approximately correct. Now, the boiling-points 
of the light petroleum spirits used in the carburation of 
air are pretty well known, and some of them are expressed 
in the following table, together with the specific gravity 
of the spirit :— 
Boiling-Points of Light Petroleum Spirit of Different 
Specific Gravity. 
Specific gravity. Boiling-point, 
0’600 .. 4° C. 
0-628 . 30 „ 
0-669 . 68 
0-699 . 92 
0726 . 118 
0741 
0-757 
136 
160 
The spirit more commonly employed has a specific gra 
vity of about 0-650, having a boiling-point of 58° C. In 
the following short table the vapour tension of this spirit 
has been calculated, by the above approximate law, for 
several different but often experienced temperatures. 
Table of Maximum Vapour Tension of Petroleum Spirit of 
a Sp. Gr. *650 at different Temperatures. 
Temperature. Vapour tension. 
- 10 ' 
0 
+10 
15 
20 
40 
C. (14°F.) . 43-5 
m.m. 
>) 
(32 
(50 
(60 
) 
) 
) 
(68 „ ) 
(104 „ ) 
81-0 
132-0 
167-9 
203-0 
301-8 
» 
» 
These vapour tensions, therefore, express the maximum 
proportionate quantities of the spirit which can exist dis¬ 
solved in air, or other medium at those temperatures; 
thus the quantity of vapour dissolved at 15° C. (60° F.) or 
the temperature of a tolerably warm day, is just about 
double that which will be dissolved at 0° C. (32° F.) or 
the freezing point of water ; the reduction of the tempera¬ 
ture from 15° to 10° C. (60° to 50° F.) is coupled with a 
loss of about one quarter of the amount of hydrocarbon 
vapour. These points are capable of direct experimental 
proof, and all claims and statements made by inventors 
may be brought with perfect justness to such results. 
We may perhaps state the above table in a still clearer 
way, by converting the figures representing the vapour 
tensions into the percentage of vapour present in any bulk 
of gas at any particular temperature. It will then stand 
thus:— 
Table of Percentage of Vapour of Petroleum Spirit of a 
Sp. Gr. *650, present in Air or other Medium at different 
Temperatures. 
Temperature. 
-10°C. (14°F.) 
0 „ (32 „ ) 
Percentage. 
.. 57 
. 10-7 
Temperature. Percentage. 
4* 10 « 
(508 F.) . 
15 „ 
(60 „ ) . 
.. 22-0 
20 „ 
(68 „ ) . 
. 27-0 
40 „ 
(104 „ ) . .... 
. 39-0 
Now, for 
an “ air gas ” scheme to be 
successful, the air 
must hold in solution a sufficient quantity of vapour at 
the lowest temperature to which it may possibly be ex¬ 
posed as shall confer upon it both inflammability and an 
adequate luminosity, and this really means that at a 
higher temperature it will hold in solution a much greater 
quantity than is necessary in order to obtain such a result. 
In many cases, doubtless, this is the case. 
The quantity of vapour held in solution at any one 
time, no matter at what temperature the observation be 
made, will be found to be just that quantity which would 
be found sufficient to saturate the air or gas at the lowest 
temperature to wdiich it has been exposed ; hence any 
lowering of the temperature after carburation should be 
carefully avoided, as a loss would thereby be incurred of 
a quantity of vapour which would not be restored on the 
temperature becoming again higher; this, of course, applies 
only to the gas or air after it has left the liquid hydro¬ 
carbon, and is not in contact with it. 
The liquid hydrocarbons, which at present are almost 
exclusively proposed to be employed for the purposes of 
carburation, are the light oils and spirit which form the 
first distillate in the preparation of paraffin oil from the 
crude Amei’ican mineral oil. As this light spirit is too 
volatile and inflammable to be burned in any sort of lamp 
at present in use, and no other commercial application 
has been discovered, very large quantities of it are dis¬ 
posed of as an entirely waste product, obtainable at a 
merely nominal cost. Whether the difficulties of impor¬ 
tation, or its taking its position as a marketable product, 
will materially affect the estimates at present put forward 
for the continuous acquirement of large quantities, will 
remain hereafter to be seen. 
(To be continued.) 
prlwmarfwij unit f tominnp. 
[ “Perfumed Spirit.” 
Court of Exchequer , June 14. Sittings at Nisi Prius, at 
Westminster, after Term , before Baron Bramwell and a 
Specicd Jury.) 
The Attorney-General v. Carmouche. 
The Attorney-General, the Solicitor-General, Mr. Locke, 
Q.C., and Mr. Pinder were counsel for the Crown. The 
defendant did not appear. 
This was an information filed by Her Majesty’s Attor¬ 
ney-General to recover from the defendant certain penal¬ 
ties for breaches of the Excise Laws. The information 
contained forty-six counts, and treble penalties were sought 
to be enforced on each count. The defendant was a 
Belgian, carrying on business at the Albion Works, Bow 
Common, and at Mark Lane, and at the former place was 
engaged in the business of an ordinary distiller, without 
having a licence to carry on that business. His advice 
notes described the spirit as “ perfumed spirit,” and his 
labels on his casks also described the spirit to be such. 
Several witnesses who had dealt with the defendant, and 
were now called as witnesses for the Crown, proved that 
there had been in some instances a perfume placed in the 
spirit, but they would not swear that it was what is 
known in the trade as “ perfumed spirit to be used for 
perfumery.” It appeared that a Mr. Watts, of the firm 
of Batley and Watts, carrying on business in Whitecross 
Street, purchased a quantity of “ perfumed ” spirit from 
the defendant, and, suspecting from the price of it that 
all was not fair and above board, instituted inquiries, and 
communicated with the Excise, and so brought about the 
exposure of the defendant’s frauds upon the Excise. Mr. 
