you must put on some of the airs of scientists and begin to learn a 

 few things by their true names. 



I shall give you but one this time and that is a short one. It is 

 oxygen. I wish you to learn that it belongs to a class called simple 

 substances. A simple substance may be divided into large or small 

 quantities, but each will still be the same substance. There are 

 many substances which we call compounds, that can be taken apart, 

 as milk. A chemist can do it. In one dish he can put the cheese 

 curd, in a very small dish the sugar, and in the largest dish the 

 water — all coming from a quart of milk. 



If the subject can be made easy for you to understand, I think 

 you will find pleasure in observing how simple substances go into 

 partnership to make compounds. 



Let us begin to make the acquaintance of oxygen. It is a great 

 friend of ours when properly controlled, but if once allowed the 

 opportunity, it is more powerful than all the giants you can imagine. 

 An interesting thing about it is that with all its capacity for power, 

 in can do nothing alone. Without a partner, it is as incapable of 

 accomplishing anytliing as one-half of a pair of shears. We find as 

 we study oxygen that it seems to revel in partnerships, and with 

 marvellous rapidity it will abandon an old one to enter a new one. 

 This entering into new partnerships and breaking up old ones is 

 something in which 1 hope you will become interested, for it lies at 

 the foundation of chemistr3\ The chemist would speak of the 

 partnership as a compound, and to keep him good-natured, we must 

 begin using some of his words. 



That you may see with your own eyes oxygen entering into a 

 compound (partnership) with another element, we will try an experi- 

 ment. The easiest way to obtain oxygen is from the air of which it 

 forms about one-fifth. I tiiink we will make the other partner 

 carbon. Charcoal is one form of carbon, and the wax in a candle 

 contains carbon ; as the latter is the handier and the cleaner, we will 

 use the candle. With a lighted match, we will heat the end of the 

 candle, which furnishes the carbon, and the oxvffen in the air bciiins 

 the partnership. 



Perhaps you think it is only guess work that there is oxygen in the 



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