Dixon — A Thcnno- Electric Method of Crj/oscnpjf. 



51 



To accommodate tlio 

 O 



couple to the apparatus the eureka wire before 

 soldering was wound on a cork support 

 (fig. 1 s), leaving some 20 cms. of each 

 end free. This cork support forms a 

 connecting-piece between two drawn 

 pine rods {p and r, fig. 1) wliich are 

 destined to carry the junctions and to 

 keep them in position, one in a test- 

 tube {a) containing the fluid to be ex- 

 amined, and the otlier ina si milar tube (&) 

 containing distilled water.' 



The two test-tubes, each about 1 cm. 

 in diameter, are supported in a large 

 perforated cork bung (c), which fits 

 loosely in an outer large test-tube, which 

 in turn is immersed in the freezing-bath, 

 and forms tlie freezing-chamber (/). The 

 perforated bvmg is held about the middle 

 of the large test-tube by a metal rod (?») 

 — a piece of stout brass wire — fixed into 

 it and passing through another bung 

 whicli closes the mouth of tlie large test- 

 tube. The rod is prolonged above the 

 second bung (rf), and forms a liandle by 

 which both bungs may be removed simul- 

 taneously from tlie freezing-chamber 

 carrying the small test-tubes in the lower 

 bung. 



The cork conneeting-pieee (*■) carry- 

 ing the eureka wire of tlie couple is 



Fig. I.— a test-tube containing solution; h test-tube containing distilled water; r and p pine 

 supports of the thermo-junctions ; s cork connecting-piece rigidly connecting )■ and^; 

 and supporting the eureka element of couple wound upon it ; c cork bung which is 

 perforated to receive the test-tubes a and b, and into which the wire m is fixed. This 

 wire works loosely in the cork s, but is fixed firmly in the upper cork hung d which 

 closes the freeziTig-chamher/. The pine rods r etnAp work loosely in perforations in 

 d. <? is a stop which may be attached to one of the xo&a p to prevent the rods slipping 

 out of the upper bung when the lower bung c carrying the test-tubes is removed from 

 the wire m; I are the copper leads passing out of the freezing-chamber; £■ is the 

 freezing-bath. 



1 If a finer wire is used, the resistance may be disposed of by winding it round the lower end of 

 the rod p, so that it remains immersed in the freezing distilled water. This eliminates any clianae 

 in the resistance due to temperature tluctnation. ■!• ■' 



