218 EFFECT OFilOT AIR BLAST APPLIED TO THE MANUFACTURE OF IRON ' 
14. Mr. snow HARRIS EXHIBITED AN 
APPARATUS OR MODIFIED ELEC- 
TROMETER, FOR PERFORMING 
THE EXPERIMENTS OF POUILLET, 
BY WHICH THE INSULATION OF 
THE GOLD LEAVES IS RENDERED 
INDEPENDENT OF THE GLASS, BY 
MEANS OF TWO RODS, TERMINAT- 
ING IN GILDED BALLS. 
To determine whether electricity is deve- 
loped during the evaporation of water or 
any liquid, a platinum crucible, containing the 
substance to be examined, is placed upon the 
cap of the electrometer, having one of 
' Deluc’s small piles communicating with the 
rods. His results were contrary to those of 
Pouillet. 
15. Dr. NEWBIGGING MADE SOME 
OBSERVATIONS UPON AN EXPERI- 
MENT WHICH HE HAD MADE WITH 
REGARD TO THE COLOUR OF AR- 
TERIAL BLOOD. 
He placed some blood in a cup containing 
green spots on its surface. The portions op- 
posite to these spots assumed a vermilion 
colour, but in no other part was this change 
visible. 
Thursday, \^th August. 
16 . Mr. HARTOP MADE SOME OBSLR- 
VATIONS ON THE EFFECT OF 
THE HOT AIR BLAST, WHEN AP- 
PLIKD TO THE MANUFACTURE 
OF IRON. 
He opposed some of the statements made 
by Dr. Clark at the last meeting of the 
Association, relative to the product and the 
quality of the iron ; the former having been 
overrated, and the latter being decidedly 
inferior, as far as Yorkshire was concerned. 
17. Dr. APJOHN EXPLAINED A FOR- 
MULA FOR ASCERTAINING THE 
SPECIFIC HEAT OF GASES ; THE 
EXPRESSION BEING 
48 a ci p 
/'=/ %- 
e 30 
He has found it to correspond almost exactly 
with experiment. He modifies it to 
(/'-/> 30 
a = % — 
48 (Z p 
If the air be quite dry, the/" (which ex- 
presses the elastic force of vapour at the dew 
point) will be unnecessary, and the formula 
becomes 
f X e 30* 
a = % — 
48 <Z p 
The experiments were made by means of 
a. syphon with short horizontal arms. Sul- 
phuric acid was introduced into the legs. 
Two bladders, the one filled with common air, 
and the other with the gas to be experi- 
mented on, were attached to one of the arms, 
and two thermometers, the one with a moist 
bulb, and the other dry, were introduced 
into the other leg. The bladder was then 
* These formula are elucidated in a paper 
in the last Volume of the Trans, of the Irish 
Academy. 
pressed, and the air forced through the acid. 
It passed over the thermometers, and gave 
the temperature of the gas at the dew point. 
This enabled the value of a to be determined, 
or the specific heat. A correction was 
made for the impurity of the gas, which was i| 
transmitted over mercury and analysed. :] 
Most of the experiments corresponded with ij 
those of the French chemists, except in one | 
or two instances. The general result obtained [ 
was, that under equal weights, the gases j 
have the same specific heat; and, under \ 
equal volumes, the specific heat is proper- | 
tional to the specific gravity, except with i! 
hydrogen, which, under equal volumes, has ! 
double the specific heat. [ 
The results are presented in the following: 
table I, 
SP. HEAT, VOLUMES. SP. GR. SP. 
HEAT. ' 
Air 
. 1-000 
1-000 
1-000 
Azote • 
9613 
0-0694 
•9877 1 
Hydrogen . . . . 
•1315 
•9722 
1-8948 
Carbonic oxide 
-1-0508 
•9722 
1*0808 1 
Carbonic acid * 
-1-667 
1-5277 
1-0916 
Nitrous oxide . 
-1-5277 
1-5277 
1-1652 
ef 30 
o= % — 
48 d p 
18. Dr. DALTON INTRODUCED THE 
SUBJECT OF A SYSTEM OF CHE- 
MICAL SYMBOLS, BY EXPLAINING 
HIS IDEAS RESPECTING THE COM- 
POSITION OF THE SIMPLE COM- 
POUNDS, AND EXHIBITED THE EX- 
PRESSIONS WHICH HE PROPOSED 
MANY YEARS AGO, TO GIVE A 
PICTORIAL VIEW OF THE MODE 
IN WHICH THE ATOMS ARE COL- 
LOCATED. 
He considers the composition of nitrous 
oxide to be 2 atoms azote, adopted by Berze- 
lius, who has not stated from whom he ob- 
tained it. Olefiant gas, he considers, is 
composed of single atoms of carbon and hy- 
drogen, while the gas which exists in coal, 
though commonly termed olefiant gas, is, in 
reality, double olefiant gas, and is termed by 
Dr. Dalton, bin-olefiant gas. This is proved 
by its affording twice the quantity of carbo- 
nic acid, and requiring twice the quantity of 
oxygen, to burn it, which olefiant gas re- 
quires. 
Mr. Whewell observed that the atoms 
might as well be supposed to be arranged in 
lines, as in the mode represented by Dalton, 
which was objected to by the latter, as being 
a tottering equilibrium. 
Mr. Babbage recommended the publica- 
tion of tables, representing the composition of 
substances by symbols,* with the addition of 
* Berzelius is erroneously considered to 
have first introduced the use of letters to ex- 
press briefly the composition of bodies. Dr. 
Thomson adopted this method in one of the 
earliest editions of his System of Chemistry, 
where he classified minerals according to their 
chemical composition. In his paper on Oxalic 
Acid, published in the Philosophical Transac- 
tions for 1807, he employs formulae of this kind. 
Berzelius indeed, has owned, that he borrow- 
ed the idea from Dr. Thomson. 
