On Steam and Brines 157 



instruments. If the whole range of the thermometer is to be 

 utilised, then the length of the receiver must be such as to 

 take the whole thermometer. The two thermometers which 

 I used in all my experiments differed slightly in length, and 

 it was convenient to have a receiver made for each. Of course 

 the longer thermometer could be used with the shorter re- 

 ceiver, so long as the temperature to be observed was not too 

 high. One receiver which I have used much has the following 

 dimensions : Total length of the body of the tube, from the 

 entrance, a, of the steam tube at the bottom to the top, c, 

 where the thermometer, , is retained by a perforated cork, is 

 30 cm. ; the length, ab, of the body for the reception of the 

 salts and brine is 16 cm., and its diameter 42 mm. The length 

 of the neck, be, is 14 cm. and diameter 13 mm. The steam 

 exit tube, d, has a diameter of 7 mm., and the entry or con- 

 necting tube, e, has the same or a slightly less diameter. The 

 entry tube is bent up parallel to the main body of the instru- 

 ment, and is connected with the boiler by a tube, G, as shown 

 in the Fig. The steam tube, C, on the boiler is important. 

 The straight portion which enters the boiler should have a 

 diameter of 8 to 9 mm. Its upper part, which is fitted with 

 a cork, should have a diameter of not more than 7 or 8 mm. 

 Steam is kept constantly in the boiler, and connection with 

 the receiver is made or broken instantly by inserting or re- 

 moving the cork. The most convenient support for the 

 receiver, whether it be used in or out of the laboratory, is an 

 ordinary tumbler or drinking glass. The tube rests on a 

 piece of cork, grooved to take the bend of the tube, and it is 

 steadied by a ring made of a piece of india-rubber tubing. 

 This form of support has many advantages. In the first 

 place, the apparatus has great stability ; then the glass is 

 transparent, and it is essential to be able to see the boiling 

 mixture during the whole course of the experiment ; also, 

 while being transparent, the glass protects the receiver from 

 excessive loss of heat. 



In the experiments to be reported, the principal thing 

 to be observed is the difference between the temperature of 

 pure saturated steam and the temperature produced by the 



