92 Comparison of the Blowpipe of Hare and Brook. 



We have, this season, availed ourselves of Mr. Hare's 

 blowpipe, and have appHed it with good success, to exhibit 

 the formation of water. For this purpose, the two tubes 

 which end in the frustrum of platina, are screwed out and 

 inserted through a cork : they are then again screwed into 

 the platina, and are lastly connected with the tubes which 

 lead to the reservoirs of gas, exactly as when we are to use 

 the compound blowpipe. 



An apothecary's bottle, which should be from fifteen to 

 eighteen inches high, and of the capacity of about three or 

 four gallons, is then filled with oxigen gas. This is easily 

 done, without the air pump, by using a tube bent twice at 

 right angles, and long enough to reach with one leg to the 

 bottom of the bottle ; the other leg is screwed to the stop 

 cock of a large bell glass ; this last is filled with oxigen gas, 

 and by being pressed into the well of the pneumatic cistern, 

 while the long leg of the bent tube is passed to the bottom 

 of the large bottle, on turning the key of the stop cock of 

 the bell glass, the oxigen gas flows in, and lifts the common 

 air out, and takes its place, thus filling the bottle with an at- 

 mosphere of oxigen gas, without resorting to the air pump, 

 and without wetting the inside of the bottle, which would,' 

 of course, render the experiment nearly nugatory, and the 

 result ambiguous. It is known when the bottle is filled with 

 oxigen gas, by bringing a taper, that instant blown out, to 

 the mouth af the bottle, when if full, the taper will be re- 

 liehted. 



Things being thus arranged, the flame of the compound 

 blow pipe is lighted, and is introduced into the bottle, taking 

 care not to bring it within nine or ten inches of the bottom : 

 the cork which is on the tubes, closes the mouth of the 

 bottle,* which is, from the first moment, kept cold by 

 copious streams of water poured incessantly over the 

 shoulders of the botde, which, if neglected for a minute or 

 two, will grow hot — the vapour of the water formed will no 

 longer condense — it remains in the condition of steam, and 

 if the bottle be tight, will produce an explosion; or, if after 

 the glass is once hot, we attempt to pour on water, the bot- 

 tle cracks. But, by reasonable attention, there is no diffi- 



* Not, however, nbsoluldy light, for fear of explosion, fiom (he great 

 ratefaclion arising from the beat. 



