( 447 ) 



is used up and only the molecules of this compound still insolution 

 will go on decomposing. 



As hence calcium hydroxide only is precipitated from the solution, 

 the composition of the liquid moves along />il/. This, however, will not 

 continue until the point M is reached because, however greatly in 

 favour of the calcium hydroxide the reaction equilibrium in the solu- 

 tion may be, a few mols. of trisaccharate are sure to remain in solution. 

 The equilibrium will be attained, for instance, when the liquid has 

 the composition indicated hy Q. 



In the same manner as stated for the complex P we can set to 

 work for any other complex containing trisaccharate. So long as the 

 point of equilibrium for that complex has not been reached the 

 saccharate will be decomposed in a way similar to that indicated 

 for the complex P. On closer consideration it appeai-s also that the 

 lines which indicate, for different complexes, the composition of the 

 liquids which are, simultaneously, in phase-equilibrium with both 

 solid substances, are all parts of a same eutectic line FG. For if 

 in the ternary system there is an equilibrium of phases, the phase 

 rule may be applied with this understanding that the number of 

 degrees of freedom is here increased by one on account of the 

 changeable inner condition of the liquid which is represented by an 

 equation with two variables. In this case, the number of degrees 

 of freedom will then be equal to one so that the possible conditions 

 are, as a rule, to be indicated by one continuous line. 



Up till now there was only a question of mols. of trisaccharate 

 and mols. of calcium hydroxide and no mention was made of mole- 

 cules of other compounds (such as monosaccharate etc.) possibly 

 in the liquid. The existence of such molecules in the solution does 

 not, however, interfere with our explanation. For this it is not at 

 all essential that the decomposition : trisaccharate = sugar -|- calcium 

 hydroxide takes place according to a simple equation. We certainly 

 have started from liquids which merely contained mols. of trisaccha- 

 rate and of calcium hydroxide, but these only represent hypothetical 

 initial and terminal conditions. 



The lines which represent the composition- of the liquids containing 

 only mols. of trisaccharate and calcium hydroxide and coexist with 

 these solid substances, respectively (the lines AB and JJE) are, 

 therefore, purely hypothetic and cannot be determined experimentally. 

 The line FG, however, may perhaps be determined experimentally 

 on the condition that the phase-equilibrium sets in more rapidly than 

 the reaction-equilibrium. We found above that the point of equili- 

 brium must be situated in a point Q. The line indicating the point 



