Is this analysis or synthesis? Complete the equation, by using weights, and explain it. Notice whether the right- hand member of the equation has the same number of atoms as the left. Has anything been lost or gained? What element has heat separated? Does the experiment show whether O is very soluble in water? How many grams of O are obtainable from 122.58 g. KCIO3? PROPERTIES. 23. Combustion of Carbon. OXYGEN Experiment 14.--Examine the gas in one of the receivers. Put a lighted splinter into the receiver, sliding along the glass cover. Remove it, blow it out, and put in again while glowing. Is it re-kindled? Repeat till it will no longer burn. Is the gas a supporter of combustion? How did the combustion compare with that in air? Is it probable that air is pure O? Why did the flame at last go out? Has the O been destroyed, or chemically united with something else? Wood is in part C. CO2 is formed by the combustion; name it. The equation is C + 2O = CO2. Affix the names and weights. Is CO2 a supporter of combustion? Note that when C is burned with plenty of O, CO2 is always formed, and that no matter how great the conflagration, the union is atom by atom. Combustion, as here shown, is only a rapid union of O with some other substance, as C or H. 24. Combustion of Sulphur. Experiment 15.--Hollow out one end of a piece of electric-light pencil, or of crayon, 3 cm. long, and attach it to a Cu wire (Fig. 9). Put into this a piece of S as large as a pea, ignite it by holding in the flame, and then hold it in a receiver of O. Note the color and brightness of the flame, and compare with the same in the air. Also note the color and odor of the product. The new gas is SO2. Name it, and write the equation for its production from S and O. How do you almost daily perform a similar experiment? Is the product a supporter of combustion? 25. Combustion of Phosphorus. Experiment 16.--With forceps, which should always be used in handling this element, put a bit of P, half as large as the S above,into the crayon, called a deflagrating-spoon. Heat another wire, touch it to the P, and at once lower the latter into a receiver of O. Notice the combustion, the color of the flame and of the product. After removing, be sure to burn every bit of P by holding it in a flame, as it is liable to take fire if left. The product of the combustion is a union of what two elements? Is it an oxide? Its symbol is P2O5. Write the equation, using symbols, names, and weights. Towards the close of the experiment, when the O is nearly all combined, P2O3 is formed, as it is also when P oxidizes at a low temperature. Name it and write the equation. 26. Combustion of Iron.