56 REPORTS ON INVESTIGATIONS AND PROJECTS. 



present has, on the contrary, decreased. The quantity of calcium present has 

 increased only 7 per cent over the preceding year instead of 18 per cent, as 

 might have been expected. The difference between these two values is more 

 than equivalent to the deficiency found for carbonates. It therefore follows 

 that a precipitation of calcium carbonate must have taken place during the 

 past year. The increase in sulphates is only 16 per cent, and since the defi- 

 ciency of calcium is a little more than equivalent to the amount by which 

 the carbonates fall short of the average increase in concentration, it would 

 seem as though a small amount of calcium sulphate has also been precipi- 

 tated. This may have resulted, however, from a change in relative concentra- 

 tion due to seepage-water from the Colorado River and to local storm-waters. 

 On the other hand, there has taken place a marked increase in the quantity 

 of iron and aluminum present, amounting to about 75 per cent for each. 



The determination of nitrates in the water for the present year was made 

 immediately after it had been received at the laboratory. In a short time, 

 however, the nitrates had entirely disappeared. As samples collected the 

 two previous years were allowed to stand for a time before being analyzed, 

 it is possible that nitrates may have been originally present in these samples 

 also, in small amounts. The increase in nitrates for 1908 over 1907 amounted 

 to only 11 per cent, instead of the average increase of 20 per cent, which 

 shows that they had undergone a partial change in composition ; while during 

 the past year they have entirely disappeared. The cause of this disappearance 

 of the nitrates is not apparent at present. The large value found for silica in 

 the first analysis may have been due to the action of the water on the glass of 

 the carboy in which the sample was collected. 



In order to interpret the action of the water upon organisms living in it, 

 and to prepare for a more skilled study of the lake in its lower stages, Prof. 

 G. J. Peirce, of Stanford University, has undertaken a study of the behavior 

 of some ponds on the flat shore of San Francisco Bay, into which water is 

 pumped from the bay for the manufacture of salt. The water rapidly evap- 

 orates during the dry season, leaving an accumulation of salt on the bottom 

 and sides of these ponds, and even more or less of a crust on parts of the 

 surface of the mother-liquor. 



From a minimum specific gravity of 1.06 in the rainy season, the concen- 

 tration rises in the course of three or four months, until the specific gravity 

 reaches 1.225. At this concentration much common salt has crystallized out, 

 leaving a mother-liquor proportionally much richer in calcium and magne- 

 sium salts than the bay water. 



A small crustacean (an Artemia described by Professor Kellogg in Science) 

 and the larvae of some flies are the only animals living, in large numbers at 

 least, in these brines. There are, however, a very considerable number of 

 plants, without exception unicellular, which live in the brines at all concen- 

 trations. These plants are bacteria of various sorts, chromogenic and other, 

 and Chlamydomonas-like algae, both green and brown, which are found in 

 various stages of their existence at different times in these ponds. These 



