relations of unequally heated Mercury and Fluid Alloys. 399 



ratus was limited in its use to such metals and alloys as are 

 solid at ordinary temperatures ; the present one is designed for 

 similarly examining such metals and alloys as are fluid at 60° F. 



Similar letters in the three figures indicate similar parts of 

 the apparatus. 



Plate II. fig. 1. A is a square wooden base, 10 inches long 

 and 5 inches wide ; B and B' are two vertical (mandril drawn) 

 tubes of brass, 12 and 10 inches long respectively, fixed firmly 

 into the wooden base ; C, C, and C" are horizontal pieces of bi'ass 

 tubing, \^ inch long x 1 inch diameter, 1^ inch long x ^ inch 

 diameter, and 1^ inch long x | inch diameter respectively, each 

 perforated across its axis with two holes of such a size as to 

 enable them to slide up and down upon the vertical tubes with 

 a moderate degree of freedom ; they constitute the supports for 

 the apparatus and spirit-lamp, and enable these to be shifted in 

 position either vertically or horizontally round the uprights. D 

 is a cork (or a piece of brass tubing split at one end) about 1^ 

 inch long, fitted rather loosely into the tube C ; it forms the chief 

 support for the apparatus by means of the metallic cross-tree D', 

 and gives additional control over the position or level of the ap- 

 paratus by being easily turned upon its axis in the tube C. The 

 cro^s-tree consists of two horizontal thin strips of elastic (ham- 

 mered) brass or German silver, about 5i inches long and | inch 

 vride at its middle part, tapering in width to ^ inch at the ends ; 

 they are soldered together at the middle part, and fixed securely 

 to the cork with their edges uppermost, either by simply making 

 a vertical saw-cut in the upper part of the cork and forcing the 

 strips into it, or more securely by first enclosing the outer end 

 of the cork in a closely-fitting short brass tube, making a similar 

 cut in it and the cork, and forcing the strips into it ; the strips 

 are bent to the form represented in fig. 2, and are held together 

 closely at their ends, when in use, by means of small metal 

 clips E, E, figs. 1 and 2. The apparatus may, by means of the 

 cross-tree, be bodily removed from connexion with the stand, 

 and without much risk of accident discharged of its contents. 



The chief part of the apparatus consists of two tubulated glass 

 bulbs, F and G, of equal size, varying from 1 L inch to 2 inches 

 in diameter; they are supported by means of the strips of metal, 

 D', clasping their upper tubulures at H ; F is provided with a 

 glass tube, I, open at both ends, 1 inch long and -^-^ inch in 

 diameter, proceeding upwards in an inclined direction towards 

 the bulb G; it is also provided with another open glass tube J. 

 G has a similar tube, K, inclined downwards, of the same size 

 as I, and connected with the latter, water-tight, by a short piece 

 of vulcanized india-rubber tubing L; it has also another open 

 glass tube, M, about 8 or 10 inches long (or more), and ^th or 



