Lesson X.] 



CHEMISTRY. 



zinc, or zinc cuttings, in a wide-mouthed 

 bottle (see Fig. 32) fitted with a glass 

 tube to deliver the gas, and one to pour 



a fluid into the bottle ; we then add dilute 

 sulphuric acid (one part of acid to five 

 parts of water) by means of the tube- 

 funnel. You then see effervescence take 

 place, and the gas rapidly issuing from 

 the tube a. Do not begin to collect any of 

 the gat until all the almoiphtric air has been 

 txptllcd from the bottle, or an explosion will 

 take place. Some chemists collect two 

 bottles, and afterwards reject the gas they 

 contain, before obtaining any for cx- 

 periir.* 



118. T. MM some examples of the 

 several methods of procuring this gas. 



llcpcat the same process as that 

 t now [Q. 117J, but substitute 



.Is for the zinc, and the gas 

 generated. Again, take a gun-barrel and 

 place a quantity of iron turnings in it, lit 

 one end with a long brass tube, and then 



e centre of the barrel red-hot, and 

 pour water slowly into the o: 

 will soon observe that gas escapes by the 

 !>o collected as usual, 



H the first supply of course. 



.as become of the oxygen 

 of the ,. 



1 hat combines i >t iron 



to form oxide o. 



iiis gas was some- 

 times collet . is it 



/ this is done by voltaic 



electricity, and r.hcn we consider clcc- 

 ic process. 



121. T. Give me some illustrations of 

 its properties. 



/'.In the first place it is the lightest 

 of all ponderable substances, being nearly 

 1 1 J times lighter than atmospheric air, and 

 16 times lighter than oxygen. In order to 

 prove this, I will perform an amusing ex- 

 periment. [Experiment 17.] I have re- 

 moved the gas-delivering tube from the 

 bottle we had before, and inserted another 

 of a different shape (A) to which a small 

 balloon, made from the lining membrane 

 of a turkey's crop, is attached. Of course, 

 the dilute sulphuric acid has been added 

 to the zinc in the bottle, 

 and the gas generated 



before the balloon was 

 attached, so as to drive 

 oft* the atmospheric air. 

 [The balloon is seen 

 tilling as in Fig. 23]. 

 hat the balloon is 

 full, I will tie a string 

 round the neck 

 and set it free. [Does 

 sol. You observ 

 it has ascended to the 

 ceiling of the room, and 

 if this was performed *.**. 



in the open air, the balloon would soon be 

 out of sight. I have another pn 



u I have got a bladder Till 

 hydrogen, and littnlto a common tobacco- 

 pipe, and you must also observe that 1 

 squeeze the neck of the bladder to ; 

 gas escaping. Now I will blow some 

 soap-bubbles by dipping of the 



to soap-suds, ami :M; the 



bladder a squeeze tinder my a; 



1 al loons lil.. drogen 



/'. I A hydrogen an inflammable 

 gas .' 



hut although it burns it docs 

 not support combustion. 



Ummable. 



