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IOWA ACADEMY OF SCIENCE Vol. XXV, 1918 



tents of tube two should be set aside as a solution of potassium 

 hypochlorite. The remainder is heated to boiling and the stream 

 of chlorine passed through it for a few moments. One to two 

 grams of potassium chlorate will <»rystallize out on cooling, and 

 it should be purified by crystallization. The characteristic reac- 

 tions of both salts should be brought out by suitable tests. 



2. TJie preparation of Sulfuric Acid: — Probably most teach- 

 ers who have used the usual cumbersome apparatus for laibora- 

 tory illustration have found it disappointing and wanting in re- 

 ality. The apparatus shown in figure 168 has been successfully 

 used in this laboratory. 



Fig. 16S 



The great European war has made difficult or impossible the 

 securing of good combustion tuibing. Ignition tubes of hard 

 glass have always been expensive and hard to get ready made. 

 For them the writer has substituted tubes made of half inch gas 

 pipe for general use in experiments requiring high temperatures, 

 such as in the preparation of nitrogen dioxide by heating lead ni- 

 trate, methane, oxygen from potassium chlorate alone, ammonia. 

 In all these cases is used a piece of pipe ten inches long capped 

 at one end w^hile the other end is reamed to take smoothly a rulb^ 

 ber stopper. 



In the ignition tube, figure 168, is placed tea to twenty grams 

 of granulated iron pyrite. The test tube contains about three c.c. 

 of concentrated nitric acid. The larger bottle may be used with 

 only its walls wet if it is desired to produce the ' ' chamber cry^s- 

 tals"; otherwise it should have its walls wet, and a few c.c. of 

 water on the bottom. The second bottle has an alkaline solution 

 to absorb the excess of gases, but is really not necessary. Air is 

 forced through from the pressure sj^stem. If no such system is 

 available the exhaust system or filtering pumps may be used. One 

 lamp is sufficient. Once the comhustion is started little external 



