( 466 ) 



A rapid cooling was effected b}' blowing a strong current of cold 

 air against the tube, the comparatively slow cooling by simj)ly leaving 

 tlie tube exposed to the air. 



This experiment, in which the tube with its contents was projected 

 on a screen to facilitate the observation, now proved that the phe- 

 nomenon of a layer of a lighter colour which all at once appears 

 at the bottom of the tube, and which rapidly increases in volume, 

 a plane of demarcation which moves upwards being clearly observable 

 all the time, has nothiiu/ to do with the phenomenon of iiiDiiLvinf/. 



In the fiist place it appeared that it was not necessary to cool 

 the liquid xqvx rapidly by blowing to bring about the [jhenomenon 

 of the two layers. If care is not taken to blow especially against 

 the lower part of the tube, blowing is even undesirable; the pheno- 

 menon in (juestiou is very clearly observed when the tube is simply 

 left exposed to the aii-. 



In the second place it was found that the phenomenon is much 

 more distinct when the narrow tube (diameter 5 mm.) is used than 

 with the wide one (20 mm.), especially because in the latter case 

 the two layers diifer nincli less in coloui'. 



In the third place it was found that when during the cooling, both 

 with blowing or without, the sulphur is stirred till the temperature 

 has fallen to 170°, and if the further cooling is made to take place 

 without stirring, the two-layer-phenomenon does not appear any more. 



This already pointed to the fact that the said phenomenon is not 

 to be ascribed to the existence of a region of non-miscibility in the 

 pseudosystem, but that it is simply brought about by the difference 

 of temperature which arises in the badly conducting column of liquid 

 sulphur at comparatively i-apid cooling. 



If, namely, a small difference of temperature occurs between 

 liquid layers which lie comparatively close to each other in the 



ranae of temperature where of the line for the internal liquid 



° ' dt 



equilibrium is large, such a large difference in ^Sy-content can exist 

 between the two layers that in consequence of the difference in 

 physical properties, as spec, weight and colour, attending this, the 

 two layers can separate, and can mo\'e along each other to find the 

 position which corresponds with their difference in specific weight. 

 In order to find out whether really considerable differences in tem- 

 perature can appear during the two layer phenomenon, the tempe- 

 rature of the two layers was determined, and though the investigation 

 in this direction leaves still room for greater accuracy, the result 

 was not doubtful. A centimeter above the plane of demarcation the 



