Hare’s Blowpipe. 299 
For this purpose, almost any kind of gasometer or air 
holder will answer; or two boxes or kegs, into which the 
gaseous materials may be pumped by a condenser, as in 
‘the case of Mr. Brooks’ apparatus, used by Clarke. Fig. 
9. A. reservoir, C. bladder holding gas, B. fe ree D. 
blowpipe. 
In default of a better mode, two smaller tubs or kegs, or 
air tight boxes inverted into larger ones, might be resorted 
to. Being filled with water, this fluid might be displaced 
by gas delivered from the vessels generating it, and the gas 
thus collected would be propelled by the pressure of the 
water through tubes connected with the compound blow- 
pipe. 
Professor Silliman uses chests sunk in his pneumatic cis- 
tern, and filled by bellows pumps,* as in my original appa- 
ratus. I now employ sometimes the shelves of my pneu- 
matic cistern, which are made like inverted trays; so that 
bell glasses filled with gas may be emptied into them by 
the hand. 
A more commodious apparatus is represented by fig. 6th. 
At A. is a cistern, divided by a partition into two apart- 
ments, in which there are two gasometers, not differing ma- 
terially from those used for confining carburetted hydrogen 
for gas lights, excepting that one of them is so contrived as 
to act asa self-regulating reservoir of hydrogen generated 
within it. A tray of copper full of holes, is supported by 
a sliding band or screw on the pipe in the centre, so as that 
it may be fixed at any desired elevation. This tray being 
covered by a stratum of granulated zinc, diluted sulphuric 
acid is poured into the containing vessel till all the atmos- 
pheric air is expelled from the gasometer through the pipe. 
situated in its axis and communicating with the blowpipe 
seen with its table annexed to the cistern. ‘The cock of 
this pipe being then closed, the action of the acid solution 
on the zine causes hydrogen to be rapidly liberated, which 
fills the gasometer; and if the latter be prevented from ris- 
ing too high, depresses the acid below the metal so as to 
suspend its action, until the escape of the gas through the 
blowpipe being permitted, (by opening the cock) the acid 
rises again over the metal and the evolution of gas recom- 
* Or more frequently by conveying the gases as they are evolved from 
the materials, through tubes immediately into the boxes. 
