28 
ANIMAL ACTIVITIES . 
piece of phosphorus. Float the cork on water in a 
soup-plate and light the phosphorus, at the same time 
lowering over it a jar of air, in such a manner that the 
mouth of the jar just dips below the 
surface of the water in the plate (Fig. 
36). The phosphorus oxide formed 
dissolves quickly in the water. The 
water rises in the jar to replace the 
oxygen used up, showing that about 
one fifth of air is oxygen. 
Remove the jar from the plate 
and thrust into the gas a lighted 
match. This colorless gas forming 
about four fifths of the air is nitro¬ 
gen. It will not burn or aid the 
burning of other substances. This 
element is found in all animal bodies 
united with other elements to form 
compounds. Bread and meat contain compounds 
partly composed of nitrogen. 
Experiment. The Element Carbon in Starch and 
Sugar. Heat in the bottom of a test- 
tube a small amount of sugar (Fig. 
37). Notice the water which col¬ 
lects on the sides of the tube. What 
are two elements found in sugar ? 
Heat slowly until no more steam 
escapes, break the tube and examine 
the residue. It is charcoal, a form 
of carbon. What three elements in 
sugar ? 
Fig. 36.—Apparatus 
for Removing 
Oxygen from Air. 
Drawn by A. E. 
Sanford. 
Repeat this experiment,using starch 
and wood. 
Graphite and diamond are other 
forms of carbon. 
Experiment. Carbon Dioxide. Burn 
Fig. 37.— Heating 
a Test-tube. 
Drawn by A. E. 
Sanford. 
in a covered 
bottle a little charcoal attached to a wire. When it 
ceases to glow remove it, and shake up the gas in the 
