Comparison of the Blowpipe of Hare and Brook. 9 J. 



Especially, would this danger be serious, were such vol- 

 umes of the gases employed as to keep up a train of experi- 

 ments for hours, without recruiting the gases. This is the 

 case in the large pneumatic cistern in the Laboratory of 

 Fale College. The recipients for gas, in this, amount col- 

 lectively to the capacity of fifty gallons ; they are all con- 

 nected at pleasure ; the gas in them, when they are full, 

 has a pressure of fifteen inches of water, and the consump- 

 tion of half a cubic foot of gas reduces the pressure only 

 one inch, and so in proportion. 



This instrument, or one on similar principles, has been in 

 use, in our hands, for- the purposes of the compound blow- 

 pipe, seventeen or eighteen years ; and no explosion ever 

 occurred, or can occur, because the well of the cistern is 

 between the two hostile gases. 



The scale of the instrument has enabled us to indulge, 

 even to luxury, in the numerous and splendid experiments 

 of fusions and combustions, which were performed on most 

 substances that possess any particular interest, in the suc- 

 cessive public courses of chemistry before the various clas- 

 ses, as well as in private researches, for years before the 

 Cambridge experiments ivere ever heard of. 



Application of Harems Bloivpipe to the synthetical formation 

 of Water. 



The synthetical formation of water, from the combustion 

 of the oxigen and hydrogen gases, is of course an interest- 

 ing experiment, to all who attend on a course of chemical 

 demonstrations. 



The apparatus of Lavoisier, or rather an enlarged and 

 improved one which we had made under our direction, in 

 London, exhibits the fact extremely well ; but the appara- 

 tus is expensive, — rather complicated, and not without some 

 practical difficulties in the use. 



was missing; and (he fragments of (iie tin extinguisher were shot out 

 among the audience, to the distance of twenty feet ail around; several 

 persons were scratched, and one young man had the right temporal artery 

 divided, so as to produce a copious hamorrhase ; perhap'! tbi= little inci- 

 dent will justify (he remarks in (he text, 



