Growth. 



33 



nient for continued use. Fit two wide-mouthed bottles of 

 equal capacity with stoppers. Make two cylindrical holes in 

 each stopper, with a round file or cork borer. Bend a short 

 piece of glass tubing at an acute angle^ and pass through the 

 cork of one bottle, and fit a short section of rubber tubing to 

 the free end, which is closed by means of a clamp. Bend a 

 second piece of glass tubing at right angles, making one arm of 

 sufficient length to extend to the bottom of the bottle. Con- 



A B 



Fig. i8. — Apparatus for generation of carbon dioxide or liydrogen. ^, bottle 

 containing fragments of marble ; B^ bottle containing hydrochloric acid ; F^ rubber 

 tubing ; Z>, clamp closing a short section of rubber tubing at outlet ; //, outlet. 



nect the short free end with the free end of a similar tube 

 which extends only fialf way to the bottom of the second bottle. 

 Fit a short section of tubing to the remaining opening in the sec- 

 ond stopper. Now place zinc or marble fragments in the first 

 bottle, and fill the second nearly full of a solution of hydro- 

 chloric acid. To generate gas, remove the clamp from the 

 outlet tube, which is suitably connected with the wash bottle. 

 Apply the mouth to the free end of the short tube of the 

 second bottle, and blow, forcing the acid over into the bottle 

 containing the zinc or marble until it is covered to a depth of a 

 3 



