676 



according to ascending quadruple point temperatnres. Tiie order in 

 temperature is the same as that in pressure. 



TABLE 5. 

 Quadruple points SLiL^G. 



Melting points. 



m-toluidine 



o-toluidine 



aniline 



p-toluidine 



30 



-15 



—7 



44 



This is indeed also necessary on account of the coincidence of 

 the LjLjG lines. 



The order of the melting-points of the pure components deviates 

 from this only in so far that m-toluidine and 6>-toluidine have exchanged 

 places. 1 have determined the four melting-points given in table 5 

 myself. That of y/i-tolnidine was not known, as far as I could find 

 out; that of o-toluidine agrees with the observation by Knoevenagel ^). 

 For the melting-point of aniline we find — 8° given; my value lies 

 somewhat higher; Timmermans' value lies again higher than mine'). 

 I think, however, that I may conclude from the small melting-range 

 presented by my pi-eparation, that the substance was pure. We find 

 45° for the melting-point of jt;-toluidine in the handbooks; my value 

 is lower, and agrees with Hüt,ktt's very carefully executed determi- 

 nation (43, 9°) »). 



The compounds that occur in these systems, contain the components 

 in the ratio 1: 1. 1 think, therefore, that 1 have to consider them 

 as carbaminic acids. These compounds were still unknown, only 

 DiTTE has evidently observed two of them in his experiments. It is 

 clear from the limits of stability of the compounds, why they have 

 not been found; at ordinary temperature only two of these compounds 

 are possible (phenyl- and /^tolylcarbaminic acid). The first decomposes 

 directly into liquid and gas, the second into solid />toluidine and gas, 

 when the tubes are opened. 



^) Ber. 40. 517. (1907). Knoevenagel finds besides the melting-point of — 15.5° 

 anothei' belonging to a metaslable modification ( — 21°). Timmermans' determination 

 ( — 24.4°) may refer to this metastable modification. 



s) TiMMEBMANS. Bull. Soc. Chim. Belg. 27. 334. (1914). 



3) HuLETT. Zeitschr. physik. Chem. 28. 650. (1899). 



