214 



SCIENTIFIC AMUSEMENTS. 



that the resulting oxide of iron is not soluble in water, and that a 

 pretty high temperature is requisite to bring about the reaction. 

 The hydrogen thus produced may be collected and examined by 

 passing the issuing mixture of steam and hydrogen through a 

 Liebig's Condenser (Expt. 36) to condense the steam, and collecting 

 the hydrogen by displacement (Expt. 104). The pneumatic trough 

 is hardly safe to use, because should anything occur to interrupt the 

 current of steam, water might be forced back by the condensation 

 of steam into the hot tube, producing an explosion, or at least 

 breaking the tube. Fig. 93 represents an arrangement by means 

 of which this danger is obviated by the simple device of connect- 

 ing a funnel tube with the steam generator ; this serves as a sort of 

 safety valve, inasmuch as air is sucked in through the funnel instead 



Fig. 93. Hydrogen from Steam and Red Hot Iron. 



of water through the delivery tube, in the event of the steam supply 

 becoming interrupted by any accident. 



Expt. 250. To burn Phosphorus in Nitrous Oxide. Prepare 

 a jar of nitrous oxide (Expt. 187) and introduce into it a bit of 

 phosphorus in a deflagrating spoon just lit by touching with a 

 hot wire as in Expt. 234. The phosphorus will burn nearly as 

 brilliantly as in oxygen. The chemical action here taking place 

 is that the nitrous oxide splits up into nitrogen and oxygen, the 

 phosphorus combining with the latter with the evolution of great 

 heat and light, whilst the nitrogen is set free. 



Expt. 251. To burn Phosphorus in Nitric Oxide. Prepare 

 a jar of nitric oxide as in Expt. 222, and introduce into it a 

 deflagrating spoon with a bit of dry phosphorus which has been 



