404 C. L. Reese — Influence of Swamp Waters in 



I obtained a series of specimens of water from both fresh 

 and salt water swamps, as well as of the deposits from the 

 bottom of the same, from the neighborhood of Georgetown, 

 South Carolina, but after a preliminary and unsuccessful test 

 for phosphate with ammonium molybdate with both of them, 

 I decided for a number of reasons, only to use the specimens 

 from the fresh water swamp. The salt waters contain very 

 little organic matter, and are constantly changing, and could 

 consequently have little eifect ; whereas the fresh swamp waters 

 are dark in color, and contain a large quantity of organic 

 matter, and are at the same time more or less stagnant, not 

 being affected by the tides at all. The material from the bot- 

 tom of salt swamps consists mainly of the roots of marsh grass, 

 whereas that from fresh swamps is composed of an accumula- 

 tion of decaying leaves, roots, etc. Finally [ have been led to 

 believe that fresh swamps have been influential in the forma- 

 tion of phosphate nodules from the fact that cypress stumps 

 are frequently found in the phosphate beds, and occasionally 

 an amber-like substance.* 



On getting no appreciable test for phosphoric acid in the 

 swamp waters, I allowed specimens of fresh swamp waters to 

 stand for two weeks mixed with precipitated and carefully 

 purified calcium phosphate, filtered, evaporated to dryness 

 ignited, and tested for phosphoric acid with negative results in 

 each case. 



I next mixed the material taken from the bottom of fresh 

 water swamps (composed of cypress and black gum leaves and 

 roots, sand, etc.), with swamp water and normal calcium phos- 

 phate, and allowed the mixture to stand one day, filtered, and 

 filtrate gave slight test for phosphoric acid. On evaporating 

 to dryness, igniting, and redissolving in nitric acid, it gave a 

 heavy yellow precipitate with ammonium molybdate, showing 

 that some of the phosphate had gone into solution. 



In subsequent experiments, by allowing the mixture to 

 stand for a longer time, I got heavy precipitates of phospho- 

 molybdate without evaporating. 



Further experiments, in which the floats of the natural 

 phosphate rock were used instead of the precipitated phosphate,, 

 gave similar results although not so marked, as should be ex- 

 pected, owing to the presence of some calcium carbonate which 

 would have a tendency to cause the phosphate to be reprecipi- 

 tated, particularly after the action of the humus materials should 

 be completed, as is shown in the results of later experiments. 

 The floats are also less finely divided, and hence we could 

 not expect the phosphate in them to be so rapidly dissolved. 



* This substance will be described in another paper. 



