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: Experiment 9.—Chemical Change, Continued. (For the Teacher.)—With the apparatus shown in Fig. 3, the teacher is to perform the familiar experiment of electrolysis of water, while the pupils take notes of all that goes on and answer on opposite page any questions which the teacher may emphasize. Note following points: How many substances have you as a result of your experiment 1 How many had. you to begin with ? How does experiment in this respect differ from preceding ? What is analysis ? What is synthesis 1 Fig. 8.—Electrolysis Of Water. Note.—The above experiment is here introduced merely to show the difference between chemical and physical changes. The analysis of water will be discussed later. Experiment 10.—Solution. Materials and Apparatus.—Large beakers, sugar, filter-paper, funnel, funnel-stand. Take 50 c. c. of water in a beaker and add to it 10 grams of finely pulverized sugar, stirring with a glass rod. Does the sugar disappear ? Where has it gone ? Is this a physical or a chemical change ? Has the sugar lost its essential characteristics ? Taste it. Fold a filter-paper and place it in the glass funnel. Support this on the funnel-stand and pour the solution into it. Does the sugar pass through as readily as water, or can you separate out the sugar ? Can you separate them by boiling away the water ? Evaporate until you get a thick sirup, and then set aside for several days. Can you dissolve clay in water ? Try it. Pass it several times through two thicknesses of filter-paper. Is this a solution 1 What is a solution ? Experiment 11.—Hot Solution. Materials and Apparatus,—Beaker, alum, mortar, and pestle. Take 25 grams of cold water in a beaker and add to it 10 grams of pulverized alum. Stir for some time. Does all the alum dissolve? Why will it...