brittain] CHEMISTR Y IN NA Tl T RE- STUD Y I O I 



bon — carbonic acid gas. This will be one proof that the carbon of 

 the food unites with oxygen in the body. But we have found that 

 this union before (in the stove, etc.) was accompanied by light and 

 heat. In this case no light appears. Let us inquire whether heat is 

 produced by the oxidation of carbon in the body. By breathing 

 closely against the bulb of the school thermometer, the teacher can 

 show that his breath, and, therefore his body, is much warmer than 

 the surrounding air. He can then show that inanimate objects in the 

 room, as water, desks, etc., in which no oxidation is going on, are 

 no warmer than the air. It will then be plain that the oxidation of 

 carbon in the body produces heat to keep the body warmer than the 

 air. So it seems that oxidation always produces heat, but sometimes 

 no light. Next, must be found how the carbon in the body obtains 

 oxygen with which to unite, and the number of inhalations per minute 

 should be counted. Every pupil should be allowed to test his own 

 breath for carbonic acid gas. Finally the children may be asked to make 

 an off-hand sketch of a human body with a piece of carbonaceous 

 food entering at the mouth, the body when the oxidation is going on 

 at a temperature of 99 degrees while the air outside is 10 degrees be- 

 low zero — with oxygen entering by the nostrils about 18 times a 

 minute and carbonic acid gas escaping by the same opening at every 

 expiration. 



Thus ends an attempt to show how the beginning of Chemistry, as 

 they may be developed in nature-lessons, without formulas or equa- 

 tions, may be used to train the pupils of the common school to 

 observe and reason, and in later life may help them in fitting together 

 intelligently their lives and their environment. 



University of New Brinswick John Brittain. 



FREr>ERICTON, N. B. 



