Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III. OXYGEN AND OZONE. OXYGEN (O; 16). 18. Preparation. In hard glass test tubes heat-separately small amounts of each of the following substances: mercuric oxide (HgO), barium peroxide (BaO2), potassium chlorate (KClO3), potassium dichromate (K2Cr2O7), Fig. 6. potassium nitrate (KNO3). In each case test the gas evolved by introducing a glowing splinter into the mouth of the tube. 19. Mix about 10 gms. of manganese dioxide (MnO2) and 10 gms. of potassium chlorate (KClO3). Arrangean apparatus as shown in Fig. 6, and introduce the mixture of MnO2 and KClO3 into the test tube. Apply heat very slowly and gradually. After a regular flow of oxygen comes from the apparatus, collect several bottles of the gas by displacement of water. (These bottles of oxygen are for use in the following experiments on the properties of the element.) What reaction has taken place in the above preparation of oxygen ? Why is the MnO2 mixed with the KClO3 ? 20. Introduce about 2 gms. of sodium peroxide (NasC) into a test tube and add about 5 cc. of water. What happens? Test the gas evolved. Is the gas oxygen ? 21. Properties. Dry a small piece of phosphorus (P) by means of filter paper and place it in a deflagrating spoon. Ignite the phosphorus by touching it with a hot file and then thrust into a bottle of oxygen. What causes the white fumes ? When the phosphorus has stopped burning, withdraw the deflagrating spoon from the bottle and introduce a piece of moistened blue litmus paper. Does the paper change? If so, what causes the change? (caution! The greatest care must be exercised in experiments involving the use of phosphorus. Phosphorus is spontaneously inflammable in the air. After finishing the above experiment the iron deflagrating spoon should be strongly ignited...