KE ACTIONS OF FISHES TO ATMOSPHERIC GASES 213 



of gases by pumps or boiling, offers no difficulties if only small 

 quantities of water are desired but if a continuous flow is needed 

 the difficulties are greatly increased. The exhausting of gases 

 with pumps is to be preferred, as it interferes less with the plank- 

 ton, the bicarbonates; it would, however, no doubt remove some 

 of the half-bound carbon dioxide and thus affect the bicarbonates 

 present in solution to some extent. 



A piece of apparatus to give a constant flow of water from 

 which the gas has been exhausted by a vacuum has been devised 

 but a good air exhaust and compression pump and considerable 

 experimentation would be necessary to perfect the first machine 

 and as yet this has been found impracticable. Apparatus which 

 boils water and gives a constant flow is. less expensive, particu- 

 larly because less skilled labor is required to build it. A com- 

 bined atmospheric deaerating and boiling device installed for the 

 control of gases is shown in figure 1. The principle is as follows: 

 The hot water of the laboratory system is passed through a 

 float valve of high grade, which regulates the flow into a storage 

 or delivery tank. Above the storage tank and between it and 

 the float valve, are two open boilers, which bring the water to 

 the boiling point, and a series of sieves which lowers the gases 

 to saturation when the boilers are not used. The water is with- 

 drawn from the storage tank through two tap water coolers. 

 When the boilers are used, the water comes off with a very low 

 gas content.' 



With the aid of figure 1 we may follow the course of the hot 

 water through the apparatus when a flow of water at cold tap 

 temperature is desired. First the water passes through valve A 

 to the float valve Fv which is opened by the lowering of the water 

 in the receiving tank. The water then passes through the 'return 

 bend' to valve F which is set so as to give about the flow desired. 

 After passing this valve the water rises to the top of the appa- 



^ The cost of such a piece of apparatus varies greatly with the conditions and 

 methods of installation. The total cost of the present piece, including labor, 

 sink, drain and small water table, was about $300. The plans were drawn and all 

 the parts ordered by the authors, who also supervised the installation. $500 to 

 $600 wouid be a fair contract price in Chicago if detailed plans were furnished. 



