Heat hy the Method of Mixtures. 



279 



heating tube by a silk cord passing over a pulley, and held taut 

 by a mass attached to the free end, whose weight is somewhat 

 less than the component weight along the track, of car and body 

 together, and somewhat greater than that of car alone. The 



2. 



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car is held in position by a pin J, on the steel wire aoc, which 

 is pivoted at a between the rails of the track. A second pin e 

 at the lower end of this wire enters a catch on the inside of 

 the door B at the lower end of the heating tube and holds it 

 closed against the tension of a coiled spring. 



The calorimeter itself is placed under the lower end of the 

 track (six or eight feet distant from the heating chamber) and 

 consists as shown in section in fig. 3 (taken at right angles to 

 the section of the heating chamber iig. 2), of an inner copper 

 chamber which differs from that ordinarily used in being much 

 shorter (diameter = height) and in having a tightly fitting bot- 

 tle-shaped top, the opening in which is just large enough to 

 admit the heated body. Just under this opening is a wire 

 basket with attached copper paddles, which is hung on three 

 light brass wires, passing freely through tubular holes at the 

 sides of the neck of the opening and on up through the outer 

 double cover of the calorimeter. They are attached above by 



