THE 



AMERICAN NATURALIST 



Vol. XLI February, 1907 No. 



AX AUTOMATIC AERATING DEMCT. EOR AQUARIA 

 LOUIS MURBACH 



The use of the water blast as a means of aerating is well enough 

 known to need no more than passing mention. Its cost is prohi- 

 bitive for smaller schools and its use Hmited to lahonitoric^ where 

 noise would not be a disturbing factor. Furtlu'riiKuc it may be 

 desirable to have an aquarium under observation in dillVn iit rooms. 

 Some time ago a simple device was described A'r//.. noI. ;!s. 



no. 453, 1904, pp. 655-661, 2 figs.) which, howrvcr. uvvv>^\vmv~^ 

 the exchange of the water in the aquarium. 'I'hi- mi^ir involve 

 the loss of organisms if the flow were contitmous a> from a tap, or 

 it would necessitate lifting the water perio(hCallv. 



These were some of the difHculties I eiicount(MV<l uhcn about a 

 year ago I wished to aerate some small a.|iiaria ci.maim'ng sea 

 water, in a class room where fresh water wa> availal)lr. but a flow 

 of sea water could not be had. .Vii oivh'iiary fihcr or varuuin 

 pump was fitted into a calcium-chloride jar about 4o cm. tall. 

 The accumulating air in the jar was carried through the -topper 

 hy a small tube to the aquarium. \ ball valve of paraffin held 

 against the lower opening of the jar by a lever and weight wa> to 

 regulate the outflow of water. This and siiiu'lar devices tri<-d. 

 failed to regulate the varying presstn-e in the su[)ply pipc<. and wa- 

 not satisfactory. If regulated for the day when more tap- were in 

 use, the pressure increased during the night, with few or no other 

 taps on, so that the fresh wattM- overflowed through the air tube 

 and diluted the sea water. 



The above obstacles were entirely overcome in a devic(> that I 

 Jiit upon the past sttmmer at the Marine Riol.)gical Lal)oratory 



61 



