SOME IMPROVED LABORATORY METHODS. 



W. S. HENDRIXSON. 



Three laboratory experiments for students in beginnings chem- 

 istry are here submitted in the hope that they may be found use- 

 ful to other teachers of chemistrv^ as they have been helpful in 

 the author's lalboratory. 



1. Bleaching powder, potassium hypochlorite and potassium 

 chlorate may be prepared in one experiment by use of the appa- 

 ratus illustrated in tig-ure 167. In the Hask U evolved chlorine 



Fig. 167 



in the usual way by use of manganese dioxide and hydrochloric 

 acid. The gas passes into the bottle which contains diluted sul- 

 furic acid, in the proportion, 1 of water to 4 of acid by volume. 

 Acid of this concentration will absor'b most of the water and 

 gaseous hydrochloric acid. The horizontal test tube contains 

 about three grams of lime spread evenly throughout the length. 

 The excess of chlorine passes from this tube into the second test 

 tube which contains a solution of five grams of potassium hy- 

 droxide in fifteen c.c. of water. This tube must be kept cool dur- 

 ing the first part of the operation. After two to three liters of 

 chlorine have been passed through about one-third of the con- 

 32 



