(231 ) 



coucentration. At the minimum cougealing-point C the liquid of 

 31.3 pCt. KNO3 solidifies to a conglomerate of two kinds of mixed 

 crystals, one with 20 pCt. aud the other with 50 pCt. K NO3. 

 Notwithstanding both kinds belong to the rhomboedric system, the 

 mixing series is not continuous. 



Below 182° three dirt'erent conditions are therefore possible in the 

 solid state: homogeneous mixed crystals (a) of — 20 pCt. K NO3, 

 homogeneous of 50 — 100 pCt. K NO3 (a') and conglomerates of the 

 limit-crystals of 20 and 50 pCt. in variable relations, in accordance 

 to the composition of the fused mass, taken as a starting point. 



The mixed crystals, either homogene or conglomerate undergo iu 

 case of further cooling, transformations from the rhomboedric to the 

 rhombic form. 



For KNO3 that transition was known at 129°.5 {G). 



For TINO3 Dr. van Eijk found for the transition temperature 



\U° (/'•). 



The determination of these temperatures for these two substances, 

 and for their mixed crystals, was effected either by observing the 

 delay in the rise or fall of the temperature, effected by the heat of 

 transformation, or by determining the temperature at which the 

 transformation becomes noticeable by the refractive power or the 

 exterior of the crystals. These latter observations are made both 

 microscopically and with the naked eye. 



Between 182° and 144° no transformation takes place; we have 

 only found, from the course of the transformation at a lower tem- 

 perature, that the limits of the homogeneous crystals cc and a' 

 diverge somewhat more at a falling temperature. At 133° these 

 limits have become: 20 pCt. and 69 pCt. K NO3. 



The transformation-temperature of the homogeneous «-crystals falls 

 with increasing K NO3 proportion from 144°— 133° (line FII)-^ the 

 correct position of line Flh-, indicating the rhombic /^'-crystals 

 formed, is however not known. The transformation temperature for 

 all conglomerates of a and a' mixed crystals is at about 133° and 

 from the fact that this temperature remains constant between 20 

 pCt. and 69 pCt. K NO3 the situation of the points Ü and Ui is 

 deducted aud the course of the lines DH and EH^. 



At 133° all the rhomboedric «-crystals of the conglomerate are 

 transformed in rhombic /^-crystals. 



Below 133° the conglomerate consists therefore of /:?- and «'- 

 crystals. The limits of these two kinds are proved equally to change 

 iu case of a further fall iu the temperature (lines Ho Jo and Ih J) 



16* 



