Description of Apparatus.
The apparatus[4]employed in this work consists of four parts:
“1) a flask, A, in which the reactions were conducted. A melting point bulb of about 40 cc. capacity, the diameter of its neck being 20 mm., was used for this purpose.
This was closed with a two-hole rubber stopper, through one hole of which passed:
2) A small glass tube,BB, running up from the flask about 40 cm., and then bent twice at right angles. One limb of this tube was surrounded by a small Liebig’s condenser, while the shorter turned down to meet—
3) a Schiff’s azotometer filled with mercury and connected at its top with the tube above mentioned. In practice it was found desirable to have a little water on the top of the mercury column.
4) Through the second hole of the rubber stopper closing the flask was passed a short piece of glass tubing bent obliquely just above the stopper and tightly connected with a rubber tube about 50 cm. long,DD. This tube was clamped near its lower end with a Mohr’s pinch-cock, while the upper was connected with the stem of a small funnel,F.
When an experiment was to be conducted, the azotometerC, was connected to the tube,B, and tied tightly, a piece of good rubber tubing being used for the connection. The reservoir of the azotometer,M, was then raised until the mercury had driven out all the air inC, and the stop-cock closed. Next the funnel F was filled with water, the pinch-cock closingDopened and the water allowed to flow down and drive out all the air in the tube. The latter was then clamped and thus kept full of water. The apparatus being now ready, the flaskA, containing the substances in the desired quantity, was made fast toBandDby means of its stopper. The stop-cock ofCopened. The flaskAwas heated in a water bath for any desired time, the oxygen being collected inCas fast asit was given off.
At the end of the experiment, all the gases which remained inAandBwere driven over into C by lowering the reservoirMand opening the pinch-cock atD. When this was accomplished the stop-cock ofCwas closed and the gases brought under atmospheric pressure by bringing the mercury inCandMto the same level.
It will be seen that in this gas volume was included the air whichAandBcontained at the beginning of the experiment.
The oxygen evolved from the contents of the flask was determined thus: After reading off the total volume of air and oxygen and reducing to normal conditions, the total volume of oxygen was obtained by absorption with phosphorus or pyrogallol, and from the residual nitrogen could be calculated from the volume of air to be deducted the total volume of gases. The remainder is the volume of oxygen sought.”