194 On the Decomposition of the Earths. [Marcn, 
That is, I find 24 per cent., or nearly 1 more of oxygen in all the 
different compounds than the above authors. 
A disquisition on the grounds of these differences would lead me 
too much into detail to be pursued on the present occasion ; and, 
besides, [ have a train cf experiments in view, suggested by Dr. 
Henry’s paper on the analysis of ammonia, which I have reason to 
think will tend to clear up some remaining obscurities, both with 
regard to the last-mentioned article, and to the compounds of azote 
and oxygen. If these should succeed, they may afford a subject 
ior an appendix to the present essay on a future occasion, 
ArticLe IV. 
A further Continuation of the Observations made by burning @ 
highly compressed Mixture of the Gaseous Constituents of Water, 
In a letter to the Editor by Edward Daniel Clarke, LL.D. Pro- 
fessor of Mineralogy in the University of Cambridge, and Member 
of the Royal Academy of Sciences at Berlin, &c. 
(To Dr. Thomson.) 
SIR, 
THE increasing powers of the gaseous blow-pipe, which I had 
called Newman’s, as being made by that artificer, but which I 
now find to have been invented by Mr. Brooke, * require some fur- 
ther observations. The improvement, suggested by Professor 
Cumming, of a pneumatic cylinder for containing water, for the 
passage of the gas, has tended greatly to ensure the safety of the 
operator ; but it has also caused the failure of certain experiments 
for the reduction of the earths to the metallic state; as it might 
have been obvious to every chemist, who is sensible of the effect 
likely to be produced by humid gases, and by the action of vapour, 
and of occasional sallies of water, from the jet of the apparatus, 
when so constructed, upon substances exercising a powerful attrac- 
tion for orygen. The absolute necessity of removing such an ob- 
stacle to success in these experiments, induced me to make trial of 
oil, as a substitute for water, in the pneumatic cylinder; and the 
consequences have surpassed my most sanguine expectations. The 
ebullition is thereby rendered more tranquil ; the heat of the ignited 
gas sustains no diminution; it is propelled in a more desiccated 
state, and the safety of the apparatus is greatly augmented. In 
the experiments with water in the cylinder, the occasional detona- 
tions, which took place above the flaid A B, sometimes forced the 
water into the tube w y3; or, if the diameter of the jet, mz, 
. were much increased, forced it into the reservoir; rendering- an 
explosion of the whole apparatus extremely probable. 
* See the description of it, by Mr. Brooke himself, Annals, vii. 367. 
