59 
quarter of section 21—something over 200 acres. Probably more than one-* 
half the area of the lake is less than 12 feet deep. Much of the bed of the 
lake is hard sand and gravel, much is fine black mud and some is white 
mud. The mud is sometimes from four to six feet deep and very thin. 
Much of the bed is covered with chara, sometimes of stunted growth, 
but often the growth is luxuriant, stems two and three feet long being 
common. The bar in the center of the west half of section 22 is covered 
with from 10 to 12 feet of water and the surface of the bar is covered with 
a mat of chara from 12 to 18 inches thick, that was so firm as to make the 
work of sounding difficult. There are several different species of pota- 
mageton growing in the lake. They grow in water of different depths, 
so that my oarsman could tell about the depth from the kind of weed. 
Large areas are covered with different species of bullrushes; pickerel weed 
is abundant and so is Vallisneria spiralis and Peltandra undulata. I was 
able to make a list of 163 plants and trees found in and around the lake. 
PHOTOMETRIC MEASUREMENTS OF DIFFERENT SAMPLES OF OIL. 
By CHARLES T. KNIppP. 
It was a question in my mind for some time whether the difference in 
the different grades of oil warrants the difference in the price—whether 
White Seal oil is worth five cents more per gallon than Eosene oil, and if 
so, what particular quality gives it its value. 
The test was a simple one, yet it required care and time in taking the 
observations to insure accurate results. Five samples of oil were fur- 
nished by the local dealers. The oil was taken from large storing tanks 
and can be considered quite pure. Each sample was tested for its quality 
and quantity of light, its specific gravity and its “flashing point.” 
The photometric test was made on a Bunsen photometer bar adjusted 
to 100 inches between centers. .The oil was burned in a student’s lamp 
and balanced against an incandescent lamp burning at 110 volts. The 
voltage was controlled by a rheostat. A new wick was used for each 
sample and the lamp was allowed to burn for a few hours before the 
measurements began. In order to keep the lamp burning at a constant 
candle power, readings were taken on the bar at intervals of fifteen 
minutes. The test for each sample extended over from five to seven 
hours. 
