324 APPENDIX 



this is apt to cause the tube to break. When the salt has melted 

 and a brisk evolution of gas is taking place, hold a glowing splin- 

 ter of wood to the mouth of the tube. Heat the fluid salt until no 

 more gas is seen to be given off, and then set aside to cool (proceed- 

 ing meanwhile with Exps. 11 and 12). When the tube is quite cold, 

 add some distilled water and warm, until a portion of the fused 

 mass has dissolved. Filter the solution into a clean test-tube, add 

 two drops of nitric acid and five drops of a solution of silver nitrate. 



EXP. 11. Dissolve about one-fourth gram of potassium chlorate 

 in distilled water and add two drops of nitric acid; then five drops 

 of silver nitrate. 



EXP. 12. Dissolve about one-fourth gram of potassium 

 chloride in distilled water and add two drops of nitric acid; then five 

 drops of silver nitrate. 



What is the behavior of potassium chlorate, and of potassium chloride, respec- 

 tively, toward nitric acid? toward silver nitrate? If a precipitate forms, 

 what must it be ? What conclusion can be drawn as to the nature of the solu- 

 tion obtained in Exp. 10 ? Write the equation expressing the result of heating 

 potassium chlorate. 



EXP. 13. Clean, dry and weigh a porcelain crucible and lid. 

 Add about one gram of potassium chlorate to the crucible, and re- 

 weigh exactly. The difference between the first and second weigh- 

 ings will give the precise amount of salt used. Set the crucible 

 upon a pipe-stem triangle, supported on an iron ring and stand, 

 and heat gradually with a Bunsen burner, until all the oxygen has 

 been expelled. This can be done without any danger of loss from 

 spattering, if the heating is conducted uniformly and slowly. When 

 the salt is in quiet fusion, allow the crucible to cool to room tempera- 

 ture, then weigh. The loss of weight will indicate the quantity of 

 oxygen driven off. How much oxygen is contained in one hundred 

 parts of potassium chlorate? 



EXP. 14. To ascertain the density of oxygen gas. The appa- 

 ratus furnished for this experiment consists of a tube filled with a 

 mixture of potassium chlorate and black oxide of manganese for 

 generating oxygen, a U-tube containing strong sulphuric acid, 

 and a delivery tube. The U-tube serves to prevent the escape of 

 everything but oxygen. Place this apparatus, with the exception 



