( 354 ) 



twice, the ester appeared to boil without decomposition at 205°, 2 

 under 758 mm. pressure. The solidifying point was constant at 23°, 7. 

 The compound, like the trichloroacetic-trichloromethyl ester, has a 

 strong tendency to undercooling; after inoculation it crystallises 

 immediately, but \yitli little linear yelocity. The heat of crystallisa- 

 tion is rather considerable. The sp.gr. at 23°,5 was 1,7336. 



From the melt, the substance crystallises in thin, colourless, mono- 

 clinic plates or needles with rectangular limitations. They are frequently 

 blunted at the angles and show right extinction. The crystals exhibit 

 a strong double-refraction: the smallest elasticity-axis coincides with 

 the longitudinal directioji, which direction is also that of the optical 

 axial plane. In convergent light an optical axis is visible at the border 

 of the field of view ; the bisetrix is of a negative character, while 

 the dispersion is exceedingly feeble so that it could not be ascertained 

 for what wave-length the axial angle is the largest. 



With NHJJH it gives trichloroacetamide with strong evolution 

 of heat. It di[f'<'rs from CC% . CO . O . CCl^ although the esters are 

 so analogous that they may almost be mistaken for each other. The 

 penetrating odour of phosgene and chloral, which both esters possess, 

 is however much more pronounced with the C'C'/g . C^J. OC6Y3 than 

 with tlie })entachloro-derivative, a fact, which is no doubt directly 

 connected with the other point of difference, viz. that CICO^C^C/^ is 

 evidently decomposed by cold water much nujre slowly than (he 

 trichloroacetic acid derivative. Moreover their melting points differ more 

 than 10^. According to x-Vnschütz and Emery the substance obtained by 

 clilorination of trichloroacetic-methyl-ester boils at 96° under 22 mm. 

 pressure; the ])entachloro-derivative obtained by myself at 104°. 



The difference between the two substances, therefore, admits of 

 no doubt ; a (|uautitative comparison as to their reaction-velocities 

 is in progress. 



§ 11. As regards the mechanism of the studied photochemical 

 decomposition it has been showji, by the experiments made up to the 

 present, that the decomposing substance can be considered as the normal 

 ferric-trichloroacetate : {C C/, CO . 0), Fe. 



With very concentrated solutions contained in u\iol-giass tubes, a 

 separation of C', C'/g takes already place after eight hours' exposure 

 to the light ; with dilute and consequently brown-coloured solutions 

 a little trichloro-acetic acid should be added first for the purpose of 

 decolourisation, that is to say for modification of the light al)sorption. 

 Still it is doubtful whether that addition really accelerates the process ; 

 from the data at disposal I should feel more inclined to conclude 



