( 538 ) 



sure always dimiiiislios from A \n /i. ilic liram-li 3 lias (liiis far only 

 been ibniid with IC'l, and KM, as observed in the pre\ ious eomnnini- 

 cation. From Stortenbeker's experiments, it may be deduced that for 

 ICl, the branch 3 extends from 34^ at 100 mm. to 22°7 at 42 mm., 

 for ICl from 22° at 24 niM. to 8' at 11 niM. Tlie peculiar boiling 

 phenomenon is, therefore, only possible between these temperatures 

 and pressures, but has not been expressly stated in the solutions 

 saturated with IClj or ICl. 



In binary systems in which a liquid with a minimum pressure 

 occurs on the three-phase line of the compound, branch 3 must 

 ahikii/s appear as shown in tig. 3 or 5. Among the examples cited 

 in the previous communication, there are sure to be found some 

 where the simultaneous boiling of the solid phase and the solution 

 may take place at 1 atm. pressure. 



Another kind of boiling-]ihenomenon may, finally, take place on 

 branch 2 of the three-phase line of a compound. This branch cannot 

 occur with the components, for the peculiarity of the brancii consists 

 in this that the saturated solution contains an excess of the compo- 

 nent B, whilst the saturated vapour contains an excess of A ; the 

 compound is, therefore, the phase whose composition is situated 

 between those of the two others. This is, of course, only possible 

 with a compound and not with one of the components. 



According to Fig. I, 3, 5, B of the previous communication branch 

 2 must occur with all compounds where coexisting liquids with an 

 e.xcess of B are possible, for it commences immediately at the 

 melting point. 



Now, this is possible with a number of hydrated salts which, 

 below their melting point, yield saturated solutions with excess of 

 salt; but the appertaining pressures are then generally so small that 

 the boiling phenomenon cannot be readily observed. In the case of 

 salt-hydrates which occur at a higher temperature so that the equi- 

 librium-pressure on their three-phase line might amount to 1 atm., 

 the solutions richer in salt seem to be very rare and no example is 

 known to me. 



An example is, however, known if H,0 is replaced by NH,. With 

 the compound NH, Br . 3 NH,, branch 2 appears and the pressures 

 are even greater than 1 atm. In tins case the boiling phenomenon 

 has been observed by me. 



Branch 2 has, however, been met repeatedly in my previous 

 researches on gas-hydrates where water is then the component B. If 

 we now take those hvdrates near solutions with more water the 



