THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[July .13, 1872. 
32 
heated externally by a furnace, so as to maintain a uni¬ 
form temperature. This was measured by the change in 
electrical resistance of a line platinum wire, and also 
by a mechanical pyrometer. The mixed gases were 
contained in gas-holders worked with strong sulphuric 
acid, both the amount of hydrochloric acid passed and 
the amount of chlorine produced being ascertained by 
passing the gases into a solution of caustic soda. 
The Lecturer then explained the numerous diagrams 
and tabulated results of experiments with which his 
discourse was illustrated, from which it would appear 
that there is a certain comparatively small range of 
temperature, between the critical limits of which the 
percentage of hydrochloric acid decomposed varies greatly, 
and that this is not the same for the chloride as for the 
sulphate of copper, being higher for the latter, although 
it is the same whether solid sulphate of copper be used 
or merely pieces of brick saturated with it. This shows 
that the action is essentially a surface action. It is, 
however, remarkable that in experiments on a large 
.scale, this temperature is invariably lower than in the 
laboratory experments, usually 100° or 150°; also, that ’ 
when the mixed gases are passed through a series of 
parallel tubes, an increased velocity in the flow of the 
gas yields only about one-third the increase of the 
amount of chlorine produced that an irregular porous 
surface does under like circumstances. 
From the results of all the experiments contained in 
the tables, the speaker inferred— 
1 . That with the same mixture of gases, at the same 
temperature, the amount of hydrochloric acid de¬ 
composed by the aid of a molecule of the copper 
salt, in a given time, depends upon the number of 
times the molecules of the mixed gases are passed 
through the sphere of action of the copper salt. 
2. That in long tubes of the same diameter the num¬ 
ber of opportunities of action in the same time 
are nearly the same at all velocities. 
3. That in long tubes of different diameters the num¬ 
ber is the same when the velocities of the currents 
of gas are in inverse proportion to the square of 
the diameters. 
4. That in porous masses the opportunities of action 
increase with increased velocities, in nearly direct 
proportion. 
fi. That, other conditions remaining the same, the 
percentage of hydrochloric acid decomposed varies 
with the square root of the proportionate volume 
of oxygen to hydrochloric acid. 
'6. That the CuCl 2 formed bears no definite proportion 
to the amount of chlorine produced. 
7. That as the sphere of action includes molecules not 
in contact with the copper salt, therefore hydro¬ 
chloric acid must be decomposed under circum¬ 
stances where the union of either element with 
the copper salt is impossible. 
The President said he need scarcely ask them further 
do record their thanks to the lecturer, for the clear and 
comprehensive account he had given them of his nu¬ 
merous and interesting experiments on the mutual action 
of hydrochloric acid and oxygen in the presence of salts 
of copper. The process for preparing chlorine, at present 
used, was essentially clumsy and unscientific ; the hy¬ 
drochloric acid given off from the salt cake was first 
dissolved in water, and then treated with manganic 
peroxide in order to liberate the chlorine, giving rise 
-at the same time, to a large amount of waste pi*oducts, 
which were thrown into our streams and polluted them. 
As especially interested in our rivers, he sincerely hoped 
the process would prove a commercial success, 
w t Dr. Williamson said he would like to ask a question 
or two for his own information. He understood that 
the mixture of air and hydrochloric acid was heated 
before being passed into the decomposing chamber; was 
it cooled again before it went into the chambers con¬ 
taining lime for the preparation of chloride of lime, and 
was the undecomposed hydrochloric acid previously 
removed by washing P 
Dr. Debus would like to know whether the sulphate 
of copper was found to be unaltered after having been 
exposed to the action of the mixed gases for a consider¬ 
able time, and also whether, when he used straight tubes 
with the mixed gases passing through at different ve¬ 
locities, the gas in both instances had attained the same 
temperature when it came in contact with the sulphate 
of copper. 
Mr. Stevenson remarked that he had no practical 
acquaintance with Mr. Deacon’s process; but he thought 
that if the old process continued to be used, we possessed 
a great advantage in Mr. Weldon’s method for revivify¬ 
ing the manganese, so that, in this revolutionary period 
of the manufacture, we had the benefit of both pro¬ 
cesses. 
Dr. Voelcker said the lecturer had made an allusion 
to the action of chromium on the mixed gases in the 
early part of his lecture; would he, perhaps, kindly 
explain what was its especial peculiarity ? 
Dr. Gladstone observed that many interesting points 
started up in one’s mind in connection with the subject, 
and he should like to know more fully why the lecturer 
believed the sphere of action to include molecules not 
in contact, and that the decomposition was not due to 
direct chemical action. It appeared to him that it was 
unnecessary to suppose the cause to be the mechanical 
striking of the molecules of the gas against the sulphate 
of copper surface, in their passage through the appai'atus, 
and therefore depending on the flow; for it must be re¬ 
membered that, when a gas was mechanically in a state 
of rest, the molecules composing the gas are in a state 
of motion, and that when we heat that gas this rate of 
motion of the molecules amongst themselves varies, al¬ 
though the gas is still mechanically at rest. 
Mr. Deacon replied that it was one thing to express 
clearly what one had carefully thought over, and another 
to answer offhand questions that embraced a wide field of 
inquiry ; moreover, he had come there to speak simply 
on the scientific aspect of his subject, and he thought it 
would save the time of the Fellows present, and avoid 
going over old ground, if they would permit him to put 
aside all technical questions, and reply only to those 
which had a scientific interest. 
In the first place, there is a definite range of tempera¬ 
ture where chlorine is freely formed, but no chloride of 
copper ; although at a higher temperature, the sulphate 
of copper is partly converted into chloride. This only 
applies to pure sulphate of copper, which, even after the 
action had been continued for six months, contained but 
mere traces of chlorine. In the presence of clay, how¬ 
ever, the sulphate of copper is decomposed, and chloride 
formed, probably owing to its containing some base 
which combines with the sulphuric acid. 
In the case where the exterior glass tube contained 
two clay tubes of different diameters, the gas coming in 
contact with the copper salt certainly had the same 
temperature, although moving with different velocities. 
With regard to his allusion to chromium, he had ex¬ 
pected—from the well-known oxidizing power of chromic 
acid—that it would have been very active, but, on the 
contrary, he had found that it was reduced to oxide of 
chromium, which is one of the most inactive substances. 
With respect to the theory he had laid before them, 
without vouching for its correctness, he could say that 
it was the only way he knew of accounting for the 
results he had obtained. 
BRITISH PHARMACEUTICAL CONFERENCE. 
A Meeting of the Committee was held on Tuesday, 
July 2nd. There were present:—Messrs. Attfield, Car- 
teighe, Greenish, Hanbury, Mackay, Moss, Savage, 
Schacht and Williams. 
The Hon. Sec., Professor Attfield, read the minutes 
