CONCLUSIONS 41 



in the corks with Httle stoppers made of glass tubing, and 

 weigh. Fill the tube F with lumps of chloride of calcium and 

 weigh. Connect the tubes and attach 

 E to the U tube C of the freshly CE==:;^^^;;:;IIjIK:>. 

 charged hydrogen apparatus (Fig. 21). ' (p 



When the whole apparatus is free 

 from air and completely filled with V^> 



pure hydrogen slowly passing through, Fig. 24. 



heat the tube E till a portion of 



the oxide of copper has been decomposed. Allow the tube 

 to cool, and when every trace of moisture has been carried 

 forward by the current of hydrogen into tube F, detach the 

 tubes E and F, plug and weigh them separately. The loss in 

 weight of E will be the weight of oxygen used. The gain in 

 weight of F will be the weight of water produced. The differ- 

 ence between the weight of water produced and oxygen used 

 will be the weight of hydrogen used. Calculate the percentage 

 composition of water, and from that the quantity of hydrogen, 

 combining with 8 parts by weight of oxygen, i.e. the combining 

 weight of oxygen up to the present taken. 



In repeating the determination to obtain a concordant result, use the 

 same tube of copper oxide, care being taken that no damp air gains access 

 to it, copper oxide being a very hygroscopic substance. If necessary 

 reoxidise the copper by passing air through the heated tube. If more 

 dilute sulphuric acid is required during the progress of the experiment, pour 

 in a few drops at a time down the side of the funnel tube, so that no air, 

 which would, of course, be fatal to a correct result, be admitted. 



XI. CONCLUSIONS 



The foregoing studies in natural science are of two kinds : — 

 (i) Those which have reference to the properties of the 



