340 On a new Form of Constant- Temperature Bath. 



The heating arrangement is as follows : — At the end of the 

 bath, where the tube C is placed, two holes are made close to 



Fig. 1. 



Fig. 2. 



X 



J 



the bottom ; through these passes the copper tube A, B. The 

 end A is coiled into a spiral of four or five turns about an 

 inch in diameter (not shown in the figure). The bath having 

 been placed on a stand in the required position, with the end 

 D away from the experimenter, the copper spiral is surrounded 

 by a roll of tin-plate, and the upper end of the tube connected 

 with the water-supply, which mast not be direct from the 

 main. The end B is then furnished with a tube to convey away 

 the water. Below the spiral is placed a Bunsen, the supply of 

 gas to which is governed by the thermostat. 



The thermostat is shown in fig. 2. The reservoir A is made 

 of thin glass tube, 30 millim. wide and about 170 millim. long; 

 to the upper end is joined a small stopcock B ; to the lower 

 end the tube C (4 millim. internal diameter) is connected (the 

 length of C is about 230 millim.) ; to the upper end of C is 

 joined a T-piece D made of a tube 6 millim. in internal diameter 

 and 80 millim. long. Finally a thin tube E, 2*5 millim. 

 in external diameter, is bent in the form shown — the longer 

 limb slightly drawn out, and a small hole made at a. The 

 reservoir A and tube C are then filled with benzoline or 

 paraffin oil, according to the temperature required for the 

 bath; and a quantity of mercury is introduced sufficient to 

 occupy the whole of the tube C and a small part of A when 

 the desired temperature is attained. The tube E is then 

 inserted into D and fastened by a small cork, in such a way 

 that the end is just below the point of juncture of C and D. 



