PRELIMINARY EXPERIMENTS 



15 



Method. Place the zinc in the flask (a), adjust the stop- 

 per (c) , and add the weak sulphuric acid through the thistle 

 tube (6). Note the 

 result. Hold an in- 

 verted test tube over 

 the delivery tube 

 (/) and remove it, 

 keeping it inverted. 

 Touch a match to the 

 open end. Result? 



Repeat the experi- 

 ment several times. 

 When you are sure 

 that there is no air 

 left in the flask r touch 

 a match to the end 

 of the delivery tube. 

 It is well to shield 

 the face when doing 



FIG. 3. Preparing hydrogen. 



this with a fan or piece of pasteboard. 



Note the color of the flame of burning hydrogen. 



Hold a bit of wire in the hydrogen flame. Note the heat. 

 Hold a piece of cold earthen plate over the hydrogen flame. 

 What forms on the plate? 



Now place an Argand lamp chimney over the burning 

 hydrogen flame and move it slowly down. What happens? 

 Try tubes of various sizes over the flame. 



Conclusion. Mention some properties of hydrogen. 

 What substance forms when hydrogen burns? 



Note. If a bit of pipe stem or a platinum tip is used, the hydro- 

 gen flame will be found to be colorless. The yellow color seen when 

 glass tips are used is due to the sodium in the glass. 



