OP ARTS AND SCIENCES. 



41 



TABLE XI. 



The comparisons above 100° were of rather more miportance than 

 those below for the purpose of the present investigation. For this 

 work the newly constructed apparatus designed by Prof. Rowland was 

 put in use for the first time. 



It consists of a massive copper ve.s.sel of circular section, having inner 

 dimensions of 18.5 cm. depth and 23 cm. diameter, and with walls and 

 bottom 1.2 cm. thick. Upon the carefully turned flange which forms 

 the upper edge of the walls is bolted a correspondingly heavy circular 

 copper plate, a projection from which enters a short distance into the 

 vessel. From the middle of this plate, and cast upon it, rises a heavy 

 copper bar of 10 cm. by 6 cm. cross-section outside, and 55 cm. high, 

 but containing a vertical channel in its broader front face having a 

 depth of 3.5 cm. and a width of 8 cm. Sheet-iron covers of suitable 

 length and about 4 cm. width are provided to close those portions of 

 the front of this channel which should be closed during the work. 

 The cylindrical vessel up to the flanges is placed within a sheet-iron 

 casing, from which rises at the back a sheet-iron outlet pipe which 

 extends upward along the back of the channelled bar to its top. The 

 heated gases escaping through ihis flue from the Bunsen burner placed 

 beneath the copper ves.^el heat the bar to any desired temperature, 

 regulation being had by means of inlet valves admitting cool air at the 

 base of the flue. 



See note to preceding table. 



