1815.] Objections to Sir H. Davy’s Theory of Chlorine. 211 
precision, since it cannot be known at what points the soldering is 
in perfect contact. hee ray DS 
The acid which I have employed with this battery consists of one 
measure of sulphuric acid diluted with about 50 equal measures of 
water; for though the ignition effected by this acid be not perma- 
nent, its duration for several seconds is sufficient for exhibiting the 
phenomenon, and for showing that it does not depend upon mere 
contact, by which only an instantaneous spark should be expected. 
Although in this description I have mentioned a wire ,,',5 of an 
inch in diameter, I am doubtful whether this thickness is the best. 
Iam, however, persuaded that nothing is gained by using a finer 
wire; for though the quantity of matter to be heated is thus less- 
éned, the surface by which it is cooled does not diminish in the 
same ratio; so that where the cooling power of the surrounding 
atmosphere is the principal obstacle to ignition, a thicker wire, 
which conveys more electricity in proportion to its cooling surface, 
will be more heated than a thin one, a fact which I not only ascer- 
tained by trials on these minute wires, but afterwards took occasion 
to confirm on the largest scale by means of the magnificent battery 
of Mr. Children in the summer of 1813, 
I remain, dear Sir, ever very faithfully yours, 
Buckingham-street, Fitzroy-square, Wa. H. Wo. aston: 
Aug. 5, 1815. 
Articte VIII. 
Objections to Sir H. Davy’s Theory of Chlorine. By J. Berzelids, 
M.D. F.R.S. Professor of Chemistry at Stockholm. 
(To Dr. Thomson.) 
SIR, Stockholm, June 6, 1815. 
I nave just recewed the English scientific journals for the last 
seven months. In one of the numbers of your Annals you express 
a wish that I should explain how the theory of Sir H. Davy respect- 
ing the nature of muriatic acid is inconsistent with the law respect- 
ing the combination of oxides with each other. I therefore give the 
following statement. 
According to the old theory, muriate of lead is composed of 100 
parts acid and 410 of oxide of lead, The submuriate of lead is 
composed of 100 acid + 410 x 4 = 1640 oxide. This salt, when 
prepared by precipitation, contains combined water, which may be 
separated by heating the salt in a retort. ‘The quantity of this water 
amounts to 1334 parts for every 1740 parts of the dry salt. Now 
the oxygen in this water is just equal to that in the oxide of lead 
present. You know, likewise, that in the submutiate of copper 
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