224 



ELEMENTARY GENERAL SCIENCE 



CHAP. 



, wool ; weigh. Add potassium chlorate and put back glass 

 wool ; weigh again. Connect up as in Fig. 113 and heat until 

 no more oxygen is evolved ; measure the volume of gas given 



FIG. 113. To Illustrate Experiment 223. 



off, that is the volume of water driven out of A. Allow the 

 tube to cool and weigh again. 



Enter your results thus : 



Wt. of tube, manganese dioxide, and potassium 



chlorate 36 '85 gms. 



Wt. of tube and manganese dioxide 35 '32 gms. 



1. Wt. of potassium chlorate 1*53 gms. 



Wt. of tube, manganese dioxide, and potassium 



chlorate 36 "85 gms. 



Wt. of tube, manganese dioxide and potassium 



chlorate, after heating 36 '25 gms. 



2. Wt. of oxygen evolved . . . 



3. Volume of oxygen 



60 gms. 

 430 c.c. 



We thus find, if the experiment is carefully performed, that from 



100 '60 



100 gms. of potassium chlorate we should obtain .- x gms., 



1 'OO 1 



i.e., 39 gms. of oxygen, and, further, that 430 c.c. of oxygen 

 weigh '60 gms. that is, 1 litre weighs 1'39 gms. We have not 

 here, however, corrected the volume of gas for the pressure and 



