557 



conically ; the piece h (also eoiiit'ally sliapetl, ground and enlarged) 

 of the heavily fusible, capillary glass-lnbe, can just he fixed into it; 

 the capillary tube thus has the form represented in fig. \, and it is 

 cut to such a length, that it can be easily caught with a pincette 

 from above through the hole h, while at its other end it reaches 

 just to a little above the bottom of T, if b is caught by the collar 

 a. The enlarged part of h is provided at its outward side with two 

 very fine, vertical canals, which thus have the function of ca]>illary 

 connections between the spaces ^-l and B. 



By means of a funnel with a broad and long stem, the crucible 

 T is now filled with a sufficient quantity of the finely pulverised 

 and dry salt; then AB is put into the bath, and as soon as the 

 salt in T is molten, the carefully cleaned capillary tube is lowered 

 very slowly into the apparatus, until b is lying just in the collar a; 

 immediately the liquid begins to rise then into the capillary tube. 

 Then both stopcocks C and d are closed, after the tube being put 

 in such a position, that the capillary lube will be just vertical; 

 this may be easily controlled by means of a plummet. If now the 

 air is eliminated from A through 6', it will appear easily to let the 

 liquid rise into the capillary tube, because the settlement of the 

 pressure-differences in .1 and B will occur only very slowly by the 

 narrow canals in b; in this way one can try to wet the walls of 

 the tube by the liquid salt, and to eliminate the air-bubbles even- 

 tually inclosed. A superfiuous rising into the capillary tube can be 

 stopped at any moment by means of the stopcock d. Reversely, by 

 sucking at (/, it Avill be possible, if necessary, to introduce air into 

 the molten salt through the capillary tube, or to remove the liquid 

 from it; also it is possible to substitute the air in AB by a neutral 

 atmosphere, e.g. by nitrogen or another gas, if desired. The experi- 

 ment being finished, the capillary tube b is removed first; the salt 

 will afterwards solidify in T, without causing the cracking of the 

 glass-tube. In such a way several experiments can be made by means 

 of a single apparatus. 



§ 3. Although this method of operating can be recommended in 

 such cases as in pj-inciple a \ery suitable one, the experimental 

 ditliculties however appeared to be of a rather appreciable magnitude. 



One of the chief difficulties was the elimination of the very small 

 air-bubbles from the liquid in the capillary tube, which appeared to 

 be transported into it, whenever the liquid begijis to rise into ihe 

 narrow tube. Notwithstanding all care, this could not be completely 

 prevented, and the column of liquid then appears as if broken into 



