Fig. 21 

 air blower. 



The 



IT 



Marine Aquaria 19 



asbestos and nitration becomes much more efficient. The 

 rate of filtration may be regulated by the vacuum produced 

 in the system. 



Aeration. The problem of aeration is easily solved in 

 laboratories supplied with compressed air. To avoid pos- 

 sible contamination of water by oil vapors from the pump 

 or by rust which often accumulates in the pipes the air is 

 washed by passing it through a wash bottle filled with 

 water. In most cases the pressure in the compressor is 

 greater than may be used conveniently for aeration. Pres- 

 sure in the wash bottle, regulated by a number of outlets 

 inserted in the rubber stopper and provided with rubber 

 tubing and screw clamps, may be very accurately adjusted 

 and the system used as a safety valve. 



To obtain quick absorption, air blown through water 

 must be delivered in the finest bubbles. 

 This is accomplished by using small 

 blocks made of porous stone (filtros) 

 mounted by means of DeKhotinsky ce- 

 ment at the end of a glass tube. (The blocks are 

 usually available at stores selling aquarium supplies 

 and fishes.) Should less efficient aeration be desired 

 air is blown through a capillary tubing or through a 

 blower (Fig. 21). 



In laboratories not equipped with compressed air, 

 aeration may be provided by a small electric pump.* 



By means of the following simple devices aeration 

 may be obtained in laboratories not provided with 

 electricity. Two glass cylinders about 8 inches long 

 and iY 2 inches wide connected by a long vertical tube 

 are mounted 4 to 5 feet apart on the wall or on a suit- 

 able stand (Fig. 22). As the water runs drop by drop 

 through the upper cylinder into a glass tube and fills 

 the lower cylinder, air is sucked through the outlet 

 (A). By regulating the level of the lower outlet (L) 

 a small pressure is produced in the lower cylinder and 

 air is driven through the outlet (C). After being ad- 

 justed the cylinders work for a long time without any 

 further attention. 



Aeration of the aquarium containing running sea- 



* Of the great variety of pumps available on the market the most convenient type for 

 a small laboratory is a model manufactured by Marco Air Product Company, Blooming- 

 field, N. J. This small and inexpensive instrument is sufficient to aerate 6 or 7 medium- 

 sized tanks. Its operation requires very little attention. 



V 



• 



VJ 



Fig. 22. — A sim- 

 ple air pump. A, 

 C, and L, outlets. 



