187 
and bottom waters, but determinations of these dissolved gases 
made by Professor Palmer immediately upon collection in the 
field, yielded results which throw some doubt upon the value of 
those made on samples which were shipped for analysis at the 
laboratory of the Chemical Survey. Twenty-four to forty-eight 
hours elapsed between the time of collection and that of anal- 
ysis, and during this time changes no doubt took place in the 
gases dissolved in the samples, so that the results of the analy- 
ses give no trustworthy basis for a statement of the amount 
of dissolved oxygen and carbon didxid in the water at the time 
of collection. 
I am indebted to Professor Palmer not only for the data of 
the chemical analyses which he has furnished me from the 
records of the Chemical Survey, but also for many other cour- 
tesies in connection with this subject. 
COMPARISON OF CHEMICAL CONDITIONS AND PLANKTON AT THE DIF- 
FERENT STATIONS. 
In Tables X.—XIII. will be found data from the chemical 
analyses of the waters of Illnois and Spoon rivers and Quiver 
and Thompson’s lakes, together with plankton data of the same 
or contiguous dates. The most important of the determinations, 
those of chlorine, oxygen consumed, free and albuminoid am- 
monia, organic nitrogen, nitrates and nitrites, as well as the 
plankton, are graphically shown in Plates X LIII.-L. 
CHEMICAL ANALYSES OF WATER FROM PLANKTON STATIONS, AVERAGEs OF ALL ANALYSES. 
PARTS PER MILLION. 
| 
| | | Residue on Bees Eieiomemaporation 3 7] Nitropen = | a a 
ve lly supe aca alle eee ee ee ieee ie 
42) | Ignition = | Ammonia | 2 | *5 3) 
ra Y Z | as Se xe 
Locality on z = rele S BA | ae a 
3 2| = eae S yale ay |? 
Be Sel esse 3 Oe eel gees |p ee 
a o 2 Y I) pe es fe ee |) seh fese MD 3] 
A BH} A|a!AH}A/;|O]/O] & < | |4/4a O Bm 
a 5 = =e | easel SA (Saar ee SS Falls 
Illinois River... 188/367. 5/304.1] 61.4 32.8] 25.1/21.6]10.4] .86 | .46 1.03),147|1.58) 1.91 2.00 
Spoon River ...... | 137/522. 3/167. 1'274.3 41.9) 24.4) 3.8/14.1] .245 | .604 |1.292'.039/1.01 -388 -969 
Quiver Lake .| 50/268. 9| 248.2) 25.1 27.5) 25.6] 4.8] 5.9) .165 | .251 -61/,023) .66) 1.62 62 
‘Thompson's Lake| 40 326.4) 1282.9! 44.6 36.5! 28.3'16.3]11.9' .422 | .546 | 1.05 -048) .64) 6.68 1.00 
* Plankton and silt averages are for collections coincident with or contiguous to collections of 
water samples. 
The foregoing table gives the number of samples analyzed 
from each locality and the averages of the different substances 
