PNEUMATIC AiTAR.-iTrSt, 577 



VII. 



* 



D*SC/i/>tion, of an A^^aratin for . tramforring G^sseS' over 

 iVuter or Mercury, &«. Bj/ the.Ks.v, Gilbert Au3ein» 

 M. R. I. A.* 



A HE difficulty of tiar.sfening gasses from one jar or re- Difficulties of 



. , .•,!'"• X t_ " transferrin* 



ceiver to another without loss, or mixture atmospheric- ^,^,3^5 ^^ ^^^ 



air, by the common mode in the pneumatic apparatus, must usual api-ara- 

 have been experienced often by philosophical chemists. "*' 

 And this difficulty is encreased when ver-y large jars are 

 used, and when the production of gas in them is inconsid- 

 erable J as when oxygen gas is olatained from vegetables 

 exposed to light, or from the decomposition of water. Of 

 the'sriiall quantity, obtained in this manner, a portion is 

 often lost in transfeirring it into a smaller jar for the purpose_vct 

 of subjecting it to examination. 5 and the result of the ex-l 

 periment is rendered uncertain, if the object be to measure 

 the quantity. In order to obviate this inconvenience, I beg 

 leave to submit to the Royal Irish Academy the description 

 of a small apparatus, which I have found to answer well, 

 and conceive may be admitted as a useful instrument into a 

 philosophical laboratoiy. 



The principle part of this apparatus consists of two pieces A new appara- 



of plate glass, with a hole of about half an inch diameter *"^'" "'•'^'^ 



these "iiiss 

 drilled through each. They should be something broader, piates'are ap- 



and about twice as long as the diameter of the jars used in P^'^'^ *° ^'''^ 



... - - . , rr^i 1 , 1 , , . mouth of the 



collecting aHo transternng the gasses. Ihe holes shoulu be jar. &c. 



disposed as in the figure. That in the plate (Fig. i.|, 



marked ^<:/J should be nearly in the middle of the piece. 



The hole in the upper plate (hj near the extreme edge. 



The upper plate is shorter than the under piate, and its edge 



is grounded air and straight, so as to fit the edge of the 



third plate, which is not drilled, and should be a square. 



piece cut off the second plate, as it is very necessary that 



these two plates should be of the same thickness. The 



* rrom the Irish r^Ieinoirs, lyoti. 



length 



