On the Blowpipe. 405 
The hydraulic blowpipe might also be converted into an ex- 
cellent gasholder for such gases as are unabsorbable by water. 
Hoping you will excuse my trespassing so long on the time and 
patience of your readers, I remain, sir, yours most obediently, 
’ H. B. Leeson. 
P. S. As it is frequently desirable to have some means of pre- 
serving the products of experiment unexposed to the action of 
the atmosphere, the operator should procure some small glass 
tubes, open at one end but hermetically sealed at the other : 
when wanted for use, nothing more is necessary than to heat 
the tube over a spirit-lamp so as to expel the air, and then in- 
troducing the product of experiment, immediately to close the 
open end of the tube by hermetically sealing it. 
The preceding Paper was accompanied by the following Letter 
from Mr. Joun Murray. 
To Dr. Tilloch. 
Siz,—In submitting to you Mr. Leeson’s description of an 
appendage to Tofft’s blowpipe, by means of which it may be 
made to substitute Brookes’s instrument for the explosive atmo- 
sphere, I take leave to add, that when Mr. L. mentioned the 
idea to me, I suggested an iron cylinder to contain mercury in- 
stead of oil or water, on the plan adopted by the Marquis Ri- 
dolfi of Florence, and which I described in a former Number of 
the “ Philosophical Magazine.” With Dr. Hope’s Safety Wire- 
gauze Box, | found it quite safe, charged with an explosive at- 
mosphere; and I may here add, that with this attached to 
Brookes’s blowpipe, I never had any explosion. I have used it 
two years, and without water or oil in the safety cistern. 
I suggested the cylindrical double valve whieh Mr. Leeson 
has modified, ‘The cane I mentioned as uniting all the advan- 
tages of a system of capillary tubes, and it is of considerable con- 
sequence to prevent explosion in the cylinder itself; for, if the 
receding explosive flame were suffered to acquire the momentum, 
it would thereby gain; the safety valve might be so injured as to 
give way altogether by the force of repeated subsequent explo- 
sions. 
I have since fitted up the safety cistern with a bundle of iron 
wires, and, with the addition of a capillary pipe as a jet, I operate 
without the least danger. 
I have deemed it proper to add these explanatory observations, 
and am, ‘with much respect, sir, your obedient servant, 
London. J. Murray. 
LXXXIII, Jw- 
