103 



Determination of Equivalent Weights of Metals. 



James H. Ransom. 



Some years ago I presented to the State Science Teachers' Association 

 a description of an apparatus for determining the equivalent weights of 

 the metals. The object was to devise an apparatus so simple and inex- 

 pensive that it might be used in every high school. That apparatus, 

 which consists only of a flaslv and stopper, gives fairly accurate results, 

 and Avhere more complicated apparatus is not available it may well be 

 used instead of giving up the determination of at least one of these most 

 important chemical constants. 



In colleges, however, where a greater variety of apparatus is avail- 

 able, it has seemed desirable to use apparatus which necessitates more 

 care in its adjustment. It is desirable because the student becomes 

 interested in working with complicated pieces, and on that account recalls 

 more vividly the thought back of the method. Also I have found that 

 with the apparatus about to be desci'ibed the students of average ability 

 obtain results more nearly in agreement with one another and with the 

 theory. 



The pieces of apparatus needed are two litre flasks, a two-hole rubber 

 stopper, separating funnel, test-tube, pinch-cock, glass tubing and rubber 

 connection. The accompanying sketch shows the apparatus when ready 

 for use. 



A weighed quantity (.0 to 1.0 grm.) of pure zinc is put into a test- 

 tube and this put into one of the litre flasks. The flask is filled with 

 water wliich has been slightly warmed to expel the dissolved air. The 

 stopper, carrying the separating funnel with the tube long enough to 

 reach to the bottom of the test-tube, and also carrying a tube bent to 

 a right angle and reaching nearly to the bottom of the flask, is ad- 

 justed in tiie flask so that the tube of the funnel will enter the test- 

 tube and reach neaiiy to the zinc. When pressing the stopper into 

 place the exit tube should be closed with the pinch-cock and the funnel 

 stop-cock opened so that water will fill the tube of the funnel up to the 

 stop-cock or above. Now by allowing Avater to flow from the funnel 



