328 Dr. T. Andrews on the Heat disengaged during the 



insulated by being surrounded by a glass tube, descends 

 througli an opening in the lid, and is connected below witli the 

 platina cup through the medium of a very fine platina wire, 

 and above with a circular disc of copper, which is seen de- 

 tached in fig. 2, and in its proper position in fig. 1. Before 

 the commencement of an experiment, this disc was firmly 

 fixed to the lid of the copper vessel, but it was also carefully 

 insulated from it. Thus, by bringing the disc and any other 

 part of the copper vessel into contact with the opposite poles 

 of a voltaic battery, the fine platina wire could be instantly 

 ignited. 



In performing an experiment, the copper vessel was first 

 filled with pure oxygen gas, the lid carrying the platina cup, 

 &c. then introduced into its place, the copper disc attached 

 to the lid, and its metallic connexion with the insulated wire 

 c carefully secured. The whole was next placed in the calo- 

 rimeter, which contained the projjcr quantity of water previ- 

 ously cooled to the required temperature, and weighed. The 

 inner vessel was secured in its place by the vertical rod a a. 

 The calorimeter was covered with a lid containing apertures 

 for the vertical rod and the thermometer, and the whole was 

 surrounded by an outer vessel of tin plate to prevent the efflacts 

 of radiation. The details of the arrangement will be obvious 

 from an inspection of fig. 1. By means of the horizontal arm 

 c c, the inner vessel could be agitated through the water in the 

 calorimeter. A pin shown at b restrained the motion of th.e 

 vertical rod within such limits that the iimer vessel was never 

 permitted to rise during the agitation above the surfiice of the 

 water in the calorimeter. Upon the sities and bottom of the 

 inner vessel small hollow knobs were placed, which maintained 

 at all times a certain distance between the two vessels. 



Previous to the commencement of an experiment, the inner 

 vessel was gently moved up and down till every part of the 

 apparatus had acquired the same temperature. The ignition 

 was effected by a similar method to that already described in 

 the previous section, by bringing the vertical rod and the cop- 

 ]iev disc respectively into contact with the terminal wires of a 

 galvanic arrangement. The same a})erture in the liil served 

 for the introduction of the thermometer and afterwards of the 

 galvanic wire. After the combination had begun, the inner 

 vessel was gently moved up and down within the calorimeter 

 for a sufficient period oF lime to allow, not only the combustion 

 to be completed, but the heat thereby produced to be uni- 

 formly distributed through the whole of the apparatus. In 

 every experiment, after the observation of the final tempera- 

 ture, the agitation was again repeated during two minutes, in 



