EXPERIMENTS IN TUK CHEMISTRY. 75 



with water in which a few crystals of iodide of potassium have 

 been dissolved, and heat. Stir the liquid, to prevent lumps. 

 When cooked, immerse in the paste slips of blotting-paper. 

 Use while moist. Be careful not to heat the glass tube too 

 hot, lest the ether vapor may ignite. Keep the jar well rilled 

 with vapor by frequently shaking it. Lower into the ozone a 

 bit of silver-leaf moistened with water ; it will quickly crumble 

 into dust, the oxyd of silver. 



34. i. To make the iodide of nitrogen, cover a few scales 

 of iodine with strong aqua ammonia. After standing for a 

 half-hour, pour off the liquid and place the brown sediment in 

 small pieces on bits of broken earthenware to dry. This will 

 require several hours. They may then be taken to the class- 

 room very carefully and exploded by a slight touch of a rod, 

 or even a feather. 



37. I. For making NO B a special apparatus is necessary 

 for complete success. The Florence flask may, however, be 

 used, and the heat of the spirit-lamp will be sufficient. The 

 fumes may be caught in the evolution flask, which is kept 

 cool by a towel frequently wet. When the retort is partially 

 cooled, at the conclusion of the process, pour in a little warm 

 water, to dissolve the sulphate of potash, otherwise the retort 

 may break by the crystallization of the salt. 



2. Mix equal parts of nitric acid and oil of vitriol (perhaps 

 a teaspoonful of each), and pour the mixture on hot finely- 

 powdered charcoal, or on a little oil of turpentine. It will 

 be oxydized with almost explosive violence. This should be 

 performed out of doors. 



3. Bits of tin may be obtained of any tinsmith. Put them 

 in a tumbler and nearly cover them with the NO 6 . In using 

 copper, the apparatus shown on page 39 is excellent. The 

 acid may be turned in gradually through the funnel tube. 

 Before putting in the acid pour into the flask warm water to 

 cover the lower end of the funnel tube, which should nearly 

 reach the bottom of the flask. When a jar is filled with the 

 NO, it may be lifted out of the water and inverted, when the 

 NO 4 will pass off in blood-red clouds. If the jar be left in 

 the cistern and one edge be lifted so as to admit a bubble of 

 air, red fumes will fill the jar. By standing a moment the 



