850 



Among Ihe- organic iiitro conipoiinds tliere are some that belong 

 lo tlie group of the pseudo aeids, as was found by Hantsch ') and 

 Holleman') in tiie investigation of broiiiincii/tenylnitroniefhane and of 

 pheiu/liiitroinefhane; tiiese substances too are to be counted among the 

 pseudo svslems. 



The same thing may lie remarked about Ihe r//;H<'Mv///a"to/, examined 

 bj Pkchmann and Dahi. •''), tiie /)i'ii.:o/ii:oc!/(ino(/i'i/ acetic ester studied 

 by F. KrOckeberg '^), Kipping's Jn'rizylUlcm-luiilvuidon^), and tolane- 

 (Uhroiiiide ") of Limpricht and Schwankrt. 



Also in tiie domain of structure isomery, tautomery or internal 

 transformation has been observed. Polak ") found a tine example 

 of this in tiie pa/n- and niildln'iizoldisiilphoinc acid and Smits and 

 VixsEBOXSK ') in iiii't/ii//rh(u/aiiid(' iiud iiiethi/Ziiiustard oil. In connection 

 with this Tkrwen ') advanced liie supposition that the structure 

 isomers should be tautomers tiiat very slowly pass into each other. 



2. Discussion of the binari/ pseudoiernan/ systeins consisting 

 of an nllotropic sidtstance and a solvent. 



The survey of organic substances given here, of winch it is 

 certain Ihat lliey are pseudo systems, can by no means lay claim 

 10 com|)ielene.ss, nor did we try to reach it. Our ])urposo was only 

 to denionslratc by a mere enumeration of some facts, how enormously 

 large is Ihe territory in organic region, on which the theory of 

 allotropy unght be tested. 



Here and there an attempt has been made to find a connection 

 between the pseudo binary and the unary melting-point diagram, 

 but this study has np\er lieen exhaustive. 



Hancuokt and his pupils have proceeded furthest in this direction, 

 but Ihe tiieory of aliolroity re(|uires more at present. 



Nor has a systematical investigation of tautomeric substances with 

 a solvent, so that we get a pseudo ternary system to study, in 

 which the situation of the isotherm for the inlerual equilibrium in 



1) Ber. 29, ü9<J, i2ï251 and 2^253 (1896). 

 ■•!) Kon. Akad. van Wetensch. Vol. XIV (1906). 

 8) Bcr. 23, 2421 (1890). 

 ') J. f. piakt. Cihem. [2] 46, 579 (1892). 

 , 47. 591 (1893). 

 ^) ._)ouni. cheui. Soc. 65, 499 (1894). 

 •■■) Lieb. Ann. 145, 348 (1868). 

 ^) Thesis for the Doctorate, Amsterdam. 

 «) These Proc. Vol. 16, p. 33. 

 '■>) Thesis for the Doctorate Amsterdam 



