FIG. 15. SPATULA (Horn).

Metals being injured by many chemicals, horn spatulas are used for mixing dry substances, and glass rods for stirring liquids instead of spoons.

TUBE.

(a)

FIG. 16.

(a) slide, (b) cover glass for use with microscope. For description of microscope, page 98.

(a) Balance used for weighing small quantities of light-weight material. Trip scales, as (b), are not highly enough sensitized for this purpose; they are, however, necessary for heavier material.

(Figs. 23-26 are mentioned last as they will not be found in the individual equipment, there being, usually, only a limited number of these articles for general use.)

5

In addition to the articles illustrated, there will be needed for each individual equipment:

A small asbestos mat.

Stoppers, preferably of rubber, to fit a test tube, a flask, and a heavy glass bottle. The test-tube stopper should have one hole through the center. There should be two stoppers for the flask and bottle, one with one hole and the other with two holes through it. These holes must be exactly the size of the glass tubing that is used.

Glass and rubber tubing about 4 inch in diameter. A piece of glass about 1/8 inch thick and 3 inches

square.

A tin or enamel dish about 2 inches deep and 101⁄2 inches in diameter.

Forceps.
Scissors.

File for cutting glass.

Glass rod. A fairly good substitute for the solid rods usually bought can be made as described on p. 14. Filter paper.

Litmus paper, blue and pink.

Thermometer, chemical.

A piece of copper wire about 9 inches long.1

Bunsen Burner

This burner was so called after the inventor, a German chemist, named Bunsen. The principles of its arrangement have been adapted to nearly all forms of gas-stove burners.

Experiment I. Object: To study the Bunsen burner. Procedure: Take the burner to pieces and examine

This list does not include the apparatus for milk testing, see page 385, nor the articles required for urinalysis.

its different parts. Put the parts together again and connect the burner with the gas pipe. Turn on and light the gas; to do so, turn on a full current of gas and hold the lighted match about two inches above and to the side of the top of the burner, then regulate the flow of gas so that there will be no waste. Close and open the air holes and notice the difference in the flame. Extinguish the flame by pinching the tube. Light the gas at the air holes. Extinguish the flame and relight the gas in the usual manner. Arrange the air holes so that there is a yellow flame. Do this by turning the small outer tube. Hold a piece of glass tubing in the flame.

How long does it take to get the tubing soft enough to bend?

a

FIG. 27. PARTS OF A BUNSEN
BURNER.

(a) Air holes.

(w) Wing top. This is used when a wide flame is needed.

Is the flame luminous, i. e., does it give light?
Is there a deposit formed on the glass tubing?

Is there much or little air entering the air holes of the burner?

Arrange the air holes so that the flame becomes blue.

In what way does this arrangement differ from that required for a yellow flame?

Is there a deposit on the tubing?

How long does it take to get the tubing soft enough to bend?