24 



Transactions of the Society. 



IV. — Aerator Suitable for Laboratory Aquaria . 

 By J. F. Gemmill, M.A. D.Sc. M.D. 



(Bead November 16, 1910.) 

 This instrument has some advantages over the one I described in a 



former number of the Journal. ; 



Fig. 2. 



It adapts itself readily to such 

 variations of pressure as occur 

 from hour to hour in the water 

 supply of towns, and accordingly 

 it is somewhat easier of adjust- 

 ment and needs less supervision 

 than the other. At the same 

 time, its construction is simpler, 

 and it provides an uninterrupted 

 supply of air. As in the former 

 instrument, the air is washed free 

 of impurities, and is under suf- 

 ficient pressure to enable it to 

 be distributed to different aquaria 

 and to be forced through such 

 nozzles (e.g. suitable pieces of 

 partly decayed wood f) as will 

 give out streams of very fine air- 

 bubbles ; also, should leakage oc- 

 cur anywhere there is no danger 

 that the aquaria may be flooded 

 with tap-water. The working of 

 the instrument will be under- 

 stood from the sketch, etc., ap- 

 pended (fig. 2). 



A. An ordinary small aspi- 

 rator of glass or metal attached 

 to a water tap, the water supply 

 being under considerable pres- 

 sure. 



B. Opening in the aspirator 

 for the entrance of air. 



C. Rubber tubing attached 

 to outflow of aspirator, and con- 

 nected with the tube E. 



* See this Journal, 1'JIO, pp. 9-13. 



t Loc. cit. 



