105 



the A\-tMght of zinc nocessary to produce 11.2 litres of liydrogeii is cal- 

 culated. (11.2 litres of hydrogen weigh one gram). 



The accuracy of the method was tested by Mr. Kimerline. a soph- 

 omore student in chemistry, who made three determinations each of 

 three metals. The average of the closely agreeing results is as follows: 

 aluminum, 9.02 (theory 9.03); magnesium, 12.08 (theory 12.18); zinc, 32.55 

 (theory 32.7). In a class of 70 freshmen who had worked in the lab- 

 oratory only 18 hours, and using horn-pan balaiu.-es, the average of 37 

 results picked at random was 31.9. 



The apparatus apparently gives good results even in the hands of In- 

 experienced men. 



