Isometrics of Liquid Matter . 341 



If a thread be cnt both in the end of the barrel and in K K, 

 these parts tend to act as lock nnts on each other at high 

 pressures. To obviate this annoyance, I devised the method 

 shown in fig. 2. Here the thread a a is movable, being on 

 the inside of a ring, rr, of steel, which fits snugly in a 

 socket of the barrel. Rotation of rr is prevented by the 

 projection s, corresponding to a slot in the barrel. In this 

 way a tight stuffing-box is obtained. The same number of 

 threads are cut both on the outside (c c) and the inside (b b) 

 cylindrical surface of K K. Thus it can be rotated without 

 moving the screw, S S T. The gasket of marine glue is 

 shown at mm. 



7. The barrel is perforated by four or more holes, suitably 

 threaded to admit the tinned machine-screws (diameter f 

 inch with 16 threads to the inch), at the end of the gauges or 

 other appurtenances. 



8. The piezometer tubes, U U U, of cold-drawn, weldless 

 steel tubing* are inserted in such a way as to insulate them 

 electrically from the barrel-end C C. A screw is cut on the 

 end of U U U, fitting into an iron flange, W W, between two 

 cylindrical jackets, X X and Y Y, of hard rubber or ivory. 

 X and Y fit the hole in the barrel and the aperture of the gland 

 Z Z very snugly. All other space within C C is filled with 

 marine glue, by compressing the thick gasket d d. To obviate 

 electric contact X X is flanged and W is of smaller diameter 

 than the hole in the end C C of the barrel. 



9. The outer end of U U U is closed by a tinned screw V 

 (fig. 5). The substance to be examined is here introduced, 

 usually in glass tubes (see next section, § 24) . As a rule these 

 tubes are adjusted within the compass of the copper vapour-bath 

 //(fig. 5), which surrounds U U excentrically. This bath is 

 a long cylinder of brazed sheet copper, containing the liquid 

 y y to be boiled. Vapours escaping are condensed in a lateral 

 tube (not shown) and run back, thus making the ebullition 

 continuous. A number of these baths are at hand. In order 

 to pass from one temperature to another, it is merely necessary 

 to slip off one vapour-bath and slide on another. The copper 

 vessels are thickly jacketed with asbestos, and the tubulures 

 h h are either closed by perforated corks, or at high tempera- 

 tures (200°-300°) by stuffing-boxes (not shown) appressing 

 the corks. The tubulure g receives the insulated platinum/ 

 platinum-iridium thermocouple for measuring the tempera- 

 ture of the bath. Tubes or jackets through which cold water 



* Obtained from John S. Leng, New York, or Philip S. Justice, 

 Philadelphia, U.SA. Both these gentlemen are Agents of an English 

 house whose address is not known to me. 



