( 159 ) 



each containing' about the quantity necessary for one experiment. 

 The proportion of the mixtures was regulated by putting together 

 quantities of a given weight of the two substances. As the deter- 

 minations were made for mixtures whose temperature of complete 

 mixture was near the critical, the liquids were divided into two 

 phases at the temperature of the room. Therefore the mixture was 

 well shaken, so that an emulsion was obtained. A certain quantity 

 of this was quickly poured into a capillar funnel, with whudi the liquid 

 was brought into the observation-tube. This tube consisted of a 

 straight tube of thick glass with about 3 m.M. inside diameter. It 

 was fused together at one end, widened in one place just as the 

 CAlLLETET-tubes are, and cemented in a brass mounting. After a 

 sufficient (juantity of the mixture was poured into this tube, the 

 stirring-contrivance was applied to the liquid, consisting of a 

 magnetised needle, round wlilch a closely fitting glass capillar was 

 slided, which was then fused together on both ends and provided 

 with glass balls to prevent its sticking to the glass walls. To bring 

 this bar In motion an electro-magnetic stir-apparatus was used, 

 like the one described by A. van Eldik (Versl. Kon. Ak. 1897). 

 After the stir-apparatus had been put in, the air-bubbles were 

 removed as much as possible, and then the mercury was put in the 

 tube. For this a not too great quantity was first carefully put in 

 at the top of the tube. If care was taken that the mercury had but 

 very little velocity, it kept sticking high in the tube, in consequence 

 of the capillarity. After that it was easy to make it glide along a 

 capillar down to a few cM. above the surface of the mixture. Now 

 mercury could be poured in by means of a caplllar-funnel, in which 

 air-bubbles could be avoided. At last the whole mercury fibre could 

 be lowered, till the lower end reached the surface of the mixture. 

 After the tube had been completely filled with mercury, it could 

 be turned upside down and placed in a steel vessel, which was in 

 connection with the forcing-pump. Within this steel vessel a glass 

 vessel filled with mercury, was placed in such a way, that the lower 

 end of the glass tube was below the surface of the mercury. The 

 space was further filled with glycerine, and the glass vessel closed 

 with a brass nut. To have it hermetically closed, rubber rings 

 are used. 



The pressure could be kept constant with this instrument for a 

 considerable time and could be read by a metal-manometer, a new 

 one specially used for these experiments. This manometer had been 

 tested, before it was received by us. As the influence of the pressure 

 proved to be very slight, little differences of pressure were not paid 



