848 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



the "dead oil" that accumulates at the bottom of the upper section of 

 the well about ouce a month, and that is all the care we give it. The 

 valves at the bottoms of the wells are now left open, and the ammonia- 

 water, freed from the "dead oil," light tar, and all insoluble matter, is 

 allowed to flow into the river as fast as it is made. It is evidently soon 

 diffused, and produces no bad effects upon the fishes that constantly 

 sport in the water, near the outlets of the wells, nor is it noticed by 

 the dwellers on the banks of the streams. 



If my explanations and drawings do not make the case clear to you, I 

 shall be glad to endeavor to elucidate any obsfture parts, and to show 

 you, or any one interested, the actual working of this simple but very 

 efficient device. 



I am, very respectfully and trul^', your friend, 



J. R. SHOTWELL. 

 Prof. Spencer F. Baird, 



United States Commissioner of Fish and Fisheries, 



Washington^ D. G. 



Surface Line. 



¥ 



■^^ 



Tar well. 



^H^ 



A is the inlet to well. B is the space filled with coke and breeze 

 through which the ammoniacal liquor passes upward, leaving the insol- 

 uble matter in the interstices of the coke. The water containing ammo- 

 nia and other soluble salts passes to the top F, and descending down 

 pipe C to chamber K, and then out through valve 1 and pipe D to river. 

 The wall G is two bricks thick from the top to E. From E to J it is 

 three bricks thick, to form a ledge for bottom, E. J is the bottom of the 

 well, three bricks thick. E, the bottom of the upper section B, is made 



