. The human body and health : an elementary text-book of essential anatomy, applied physiology and practical hygiene for schools . t one fifth of the solid portion of all living lifeless compounds contain it. Oxygen may easily be prepared by heating together ina test tube black oxide of manganese and chlorate of pot-ash. To catch thegas, arrange a bentglass tube with itsone end through thecork in the test tubeand the other pass-ing just within themouth of a bottlefilled with waterand turned upsidedown in a dish ofwater (Fig. 18).The bottle is filledwith water at firstto expel the a
. The human body and health : an elementary text-book of essential anatomy, applied physiology and practical hygiene for schools . t one fifth of the solid portion of all living lifeless compounds contain it. Oxygen may easily be prepared by heating together ina test tube black oxide of manganese and chlorate of pot-ash. To catch thegas, arrange a bentglass tube with itsone end through thecork in the test tubeand the other pass-ing just within themouth of a bottlefilled with waterand turned upsidedown in a dish ofwater (Fig. 18).The bottle is filledwith water at firstto expel the air. Properties of Oxygen. — Oxygen is the most importantof all the elements, and is absolutely necessary for the lifeof animals. No fire can burn without it. It differs fromthe other elements in the fact that it may be made to joinitself to nearly all the elements. Iron exposed to theair rusts. The rust is the union of iron and oxygen,and is called iron oxide. Carbon, when heated, uniteswith oxygen to form carbon dioxide. When oxygen combines with any substance, the pro-cess is named oxidation. The substance with which the. Fig. 18. — Making oxygen, e, rubber tube; n,chlorate of potash and black oxide of manga-nese ; o, oxygen which is bubbling out from t,the test tube. 82 LIFE PKOCESSES oxygen unites is said to be oxidized. Burning a matchmeans oxidizing tlie wood. Any piece of timber lying out-of-doors slowly is slow oxida-tion. The oxygenof the air is made Fig. 19. - A match being oxidized. ^q combine with the wood by means of very tiny plants called bacteria. Thesecannot grow unless
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