14 BULLETIN 672, TJ. B. DEPARTMENT OF AGRICULTURE. 



Another theory that attracted much attention was the supposition 

 that the birds were poisoned by sulphurous or sulphuric acid resulting 

 from waste from the great smelters near Salt Lake City. It was 

 believed that sulphur from the smelter smoke, depositing on vegeta- 

 tion, was washed into the streams and marshes by rains, and that 

 in combination with moisture it formed sulphurous and sulphuric 

 acid. It was supposed that the ducks in feeding found this in 

 quantities sufficient to be fatal. It was found, however, that small 

 quantities of these acids, diluted as they must be hi nature, had no 

 effect upon ducks, and birds were able to withstand for a con- 

 siderable period solutions strong enough to be very sour. In these 

 experiments the characteristic appearances and actions of the 

 duck sickness were not produced. Further, the fact that the sick 

 birds are. found in the Tulare basin and elsewhere where there are 

 no smelters, and where there is no other appreciable trade waste 

 of sulphur, serves at once to refute this theory. 



Many contended that waste water from the settling ponds of the 

 sugar factories was at the bottom of the trouble. This seemed 

 plausible, as sugar factories are located on each of the three rivers in 

 Utah on whose drainage sick ducks occur. Those who supported 

 this theory attributed the affection either to sulphuric acid used in 

 great quantities in the factories and allowed to escape through drains, 

 or to toxic matter from bacterial agencies generated in the catch 

 ponds that receive the factory drainage. The first supposition has 

 been shown to be untenable. As regards the second, the drainage 

 from these ponds enters the rivers in quantity only during the season 

 that the factories operate in fall. By the time this drainage reaches 

 the marshes in abundance few ducks are dying, and finally the mor- 

 tality ceases while the mills are still in operation. In 1914, drainage 

 from these settling ponds emptying into the Weber came down with 

 the rise in the water level consequent upon the cessation of general 

 irrigation in mid-September, and there was sufficient toxic matter 

 present to kill large numbers of carp and chubs in the lower channels. 

 Many fish-eating birds (all subject to the duck sickness under proper 

 conditions) were attracted by the abundance of fish floating helpless 

 on the water and fed here until these fish disappeared, but no birds 

 were found sick. During late summer many sick ducks had been 

 found along the lower reaches of the Weber where it spreads out on 

 the lake front, but with this rise in the water, conditions among the 

 ducks improved immediately. As in other cases the fact that the 

 duck sickness occurs in areas where there are no sugar factories serves 

 to militate against the theory that toxic matter in factory drainage 

 is the cause. 



In addition to these, the trouble has been ascribed variously to the 

 presence of sewage in the water, parasitic nematodes, arsenic poisoning, 

 and other minor hypotheses, none of which has been found tenable. 



