ARTICI.E IX. — Bquipmcnt for maintaining a Plow of O.vygcn-frec 

 Water, and for controlling Gas Content* By Victor E. Shelford. 



In Article VI of this volume a piece of apparatus for controlling 

 gas content and adding gases and fluids to water is described by the 

 present writer. His earlier work, as well as that reported by Dr. Wells 

 in Article VIII, was done with that apparatus on a water table of 

 temporary construction, but the table and the apparatus have both 

 been replaced by the permanent structures herein described. The new 

 equipment consists of a large drain-table (13), shown in the lower 

 part of the accompanying figure, with the boilers on the floor above. 

 The drain table is provided with double-decked towers nine feet high, 

 for supporting bottles, tanks, etc. in the manner indicated in articles 

 VI and VIII of this volume. Aside from possessing many advantages 

 in the control of conditions where fluids and gases are added, the new 

 apparatus has great advantages in the control of oxygen content, as 

 continuous flow is insured, and with aerating troughs of various 

 lengths almost any amount of oxygen can be obtained in running 

 water. The other apparatusf used gas heat for boiling and could de- 

 liver not more than 100 c.c. of oxygen-free water per minute, and this 

 amount was not certain to be free from oxygen continuously. The 

 new piece of apparatus delivers a liter of water per minute and could 

 probably deliver a maximum of four or five liters per minute. 



It uses high pressure steam for boiling the water and deliv- 

 ers it with the temperature brought down to that of the water sup- 

 ply. We may accordingly follow the course of the water supply from 

 the supply pipe to the exit from the cooling coil. Water is introduced 

 into the first boiler, No. i, from the supply pipe at the right of the 

 upper group of apparatus. It is passed through a Schutte & Koerting 

 i^" strainer to an inclosed float cock, No. 9. This float cock, a stock 

 article on the market, maintains water at a definite level in both tank 



*The apparatus described in this article was developed in connection with the 

 work on stream pollution done by the author and described in Article 6 of this volume; 

 the new apparatus was provided by the University of Illinois in the new Vivarium 

 Building to supersede the piece described in that article. The drawing was provided 

 by the Department of Zoology. 



tSee Shelford and Allee, Journal of Experimental Zoology, Vol. 14, pp. 207-266. 

 1913. 



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