( 178 ) 



(j(l we go to the i)oiiit A, where at 247° all aiilhracliiiioii has 

 exactly been dissolved. If we now increase the temperature still 

 more we come into the region of unsaturated solutions; from A 

 therefore, we go parallel to the T'-axis upwards to the temperature 

 350^ where the unsaturated solution has reached its critical tem- 

 perature and all passes into the gaseous state. 



The influence, which greatlj diminishes the accuracy of the results, 

 is the dependency of the volume; the error created by it, is small 

 for the critical curve a/j and for the solubility curve hq, because 

 these curves have a rather slight cui-vatiire. For the critical curve txj 

 and especially f<»r iho lower j>art ihe i)OSsiole error in the concentra- 

 tion is rather great, so that the point q is pretty uncertain. 



It seemed xevy interesting to me to investigate, whether or not it 

 would be possible to determine points of the mctasta,ble part of the 

 critical curve. I indeed succeeded to get between the tem[>eratures 

 f, and /, a solution, which, as discussed before, was supersaturated. 

 A tul)e filled with ()"/„ ajithrachinon and 94"/o ether was heated in 

 the air-bath. The solution saturated at the first critical temperature 

 containing only 5"/„ anthrachinon, some solid anthrachinon was still 

 left above the critical temperature of 195^ At increase of temperature 

 alwavs more anthrachinon passed into vapour and at last all had 

 become gas. Now, if I made the temperature fall rather quickly, no 

 solid anthrachinon was deposited, which would have been normal, 

 but at 211^ a nebula appeared and a supersaturated solution was 

 formed. Then, when I made the temperature fall slowly, the solution 

 remained over a range of temi)eratnre of 9°. At 202^ snddeidy 

 a transformation api)eared by which the solution passed iiito solid 

 anthrachinon and vajjour and the metastable i)hase disai)i)eared. 

 On subtracting more heat the formation of nebula once more a])peared 

 at ±195^ the first critical temperature of the saturated solution, and 

 for the second time a liqui*! was formed, Init llo^v this liquid was 

 a stable phase. This phenomenon shows, that vapours are also possible, 

 which are .supi^rsatu rated of solid and for their transition into the 

 stable phase choose a round-about way by another metastable i>hase, 

 viz. a supersaturated solution. 



I repeated the same experiment with a greater anthrachinon-con- 

 centration ; now the formation of nebula appeared :at 216^ it is true, 

 but before a visible quantity of liquid had l)een formed, solid anthra- 

 chinon already was deposited. These two temperatures could not serve 

 to determine the metastable part of the critical curve, because the 

 vapour-space in the tube hapi)ened to be too large. So the tempera- 

 tures under observation were ]iot critical temperatures. 



