278 Wadsworth — Determinatio?i of Specific 



and makes the maximum more sharply defined. The greatest 

 drawback to the use of this method is the preliminary labor of 

 observing for and computing T and j3. But this preliminary 

 labor is well worth while, when the highest degree of accuracy 

 is aimed at. 



Conclusion. — It appears then from the preceding discussion 

 that the greatest possible care should be taken in reading tem- 

 peratures, and since the errors of these readings are much 

 greater than any others likely to be committed, it is advisable, 

 in order to minimize the effect of these errors, to use 



1. A small amount of water in the calorimeter ; i. e., a small 

 calorimeter. 



2. A large mass of metal having a maximum surface for 

 given weight (sheets or wire) ; 



3. As high an initial temperature, T, as can be conveniently 

 attained. 



4. The calorimeter should be surrounded by a water jacket 

 maintained at a constant temperature /3, higher than the initial 

 temperature t of the water in the calorimeter by the amount 

 determined by (21) and (13). 



. Physical Laboratory, Ohio State University, 

 December, 1888. 



NOTES ON OALORIMETRT. 



The ordinary method of transferring the hot body from the 

 heating chamber to the calorimeter by allowing it to slide 

 down and out of an inclined tube into the mouth of the calori- 

 meter is open to a number of objections, chief among which is 

 the loss of heat in passing through the air, the loss of water 

 by splashing, etc., and more important than all else, the loss 

 of time in moving the calorimeter up to and away from the 

 heating chamber, and in uncovering and covering the calori- 

 meter at the most critical stage of the operation, when the 

 attention of the observer should be entirely directed to the 

 reading of temperatures, and disturbing influences should be 

 reduced to a minimum. To avoid these difficulties I devised 

 some time ago the arrangement shown in fig. 2. The tube, 

 which forms the heating chamber of a Regnault apparatus, is 

 removed and replaced in a more nearly horizontal position, A, 

 B, fig. 2. A track consisting of two parallel steel wires, tied 

 together at intervals, is laid along the bottom of this tube and 

 continues for some distance beyond the lower end. On this 

 track rolls a square (or cylindrical) double-walled car of sheet 

 copper, mounted on four wheels, two (on one side) with 



frooved faces, and two (on the other side) with straight faces. 

 n this car is placed, just over a trap door at the forward end, 

 the object whose specific heat is to be determined. When the 

 latter is being heated the car containing it is drawn up into the 



