156 BRIDGMAN. 



Because of an accident the exploration witli acetanilide at room 

 temperature was made only between 6000 and 12000. At 200°, the 

 approximate coordinates of the melting curve were found to be 6400 

 kgm. with a change of volume of 0.070 cm.'^/gm. The melting point 

 at atmospheric pressure is in the neighborhood of 113°. 



Benzol Derivatives with Substitutions for Two Atoms. — 

 Orthokresol * ; para nitro-phenol, monoclinic; para toluidine; anethol. 



A unique feature of the phase diagram of o-kresol is that the melting 

 curve of I can \:>e realized at hiylier temperatures in the region of II. 

 It is perhaps surprising that p-toluidine does not show another form 

 like o-kresol, since the substituting groups differ so little in molecular 

 weight. 



Camphor Group. — ^ Camphor *, trigonal ; monobrom-camphor; di- 

 bromcamphor; phenylated camphor. 



Ordinary camphor has one of the most complicated phase diagrams ; 

 it was a surprise that at least monobrom camphor did not have other 

 forms. Monobrom camphor decomposes at about 4000 kgm. at 200° 

 when pressure is released from 12000. Apparently there is no free 

 bromine among the decomposition products. Dibrom camphor at 

 200° decomposed when pressure had been released from 12000 to 

 8000 with so large an increase of volume that pressure rose again to 

 12000. The products of the decomposition were a suffocating gas 

 and much free bromine. There were many indications that neither 

 of these brom camphors began to decompose at 200° until reaching 

 the melting curve. The high pressure as well as the high temperature 

 must play some part in the decomposition, because both of them melt 

 quietly on heating to 200° at atmospheric pressure. Pressure was 

 transmitted to these substances by mercury, so that the kerosene could 

 have had no part in the decomposition. 



Runs on phenylated camphor were made at 0°, 20° and 180°. The 

 melting point at atmospheric pressure is —23°; at 180°, 12000 kgm. 

 was not high enough to freeze it. 



Compounds of the Type C = O 



\R2 



Carbamide *, tetragonal ; Acetic Acid*; Acetamide *, trigonal ; Ace- 

 tone; Formamide; Formic Acid; Oxamide, monoclinic; Propionic 

 Acid. 



The first three of these substances form a sub-group very closely 



