188 Alfred J. Ea-ari: 



bleaclied in three chiys. The wuter in tlie reeeivei- gave Schiff' s test 

 strongly, Seliryvers, Kinmiers, and thL' Schiff and sulphuric acid 

 tests faintly. It apjiaiently contained a trace of formaldehyde 

 in addition to a trace of acetone, but not sufhcient of the former 

 to give the characteristic smell. 



Apparently when subject to violent photo-chenucal oxidation 

 pure xanthophyll may produce traces of formaldehyde, but none 

 when tlie oxidation takes place in darkness or in weak illumination 

 or under water. According to Willstatter, Mayer, and Hlini 

 (Annalen. 1910. p. 73), the constitutional formula of phytol may 

 be 



CH,-CH-CH-CH-CH-CH-CH - C = C - CH-CH.,0 

 I I I I I I I I I 



CH, CK, CH, CH, CH, CH, CH, CB, CH, 



Phytol would therefore be constructed from similai- l)uilding 

 materials to alipliatic and cyclic terpenes and rublx-r. Just as 

 geraniol and limonol may be constructed from two molecules of 

 isoprene, so may four molecules form phytol. as thus : — 

 4C,H, + H".,0 + 3H, = r'.,„H,„0 



In the same way eight molecules of isoprene might yield cai-otin 

 <C,uti,,,) or xanthophyll (C,oH,,,0,,). 



8C,H„ + 2.0,,=G,„H,,, + 4H.,0 

 8C,,Hh + 3.0.,=C,„H,A + 4H.,0 



It would not be surprising that under violent photo-oxidation 

 some of tlie CH — CHj components of carotin, as well as of phytol, 

 and hence also of chlorophyll, might be torn away, and oxidized to 

 formaldehyde, and as thus (CH -CHg) + 0^, = 2 CH^O. If so. the 

 presence of two additional atoms of oxygen in tlie xanthophyll mole- 

 cule renders it not only more stable in this respect, but also more 

 resistant to oxidation than is carotin. 



According to Willstatter and Stoll, pulverised xanthoi)liyll takes 

 up 36.5% by weight of oxygen and produces a compound which 

 when precipitated fi'om methyl alcohol by ether has the formula 

 CioHsfiO^^ This is, however, merely a percentage formula, and 

 gives no indication of the mode of union of the oxyg^ii. 



The orUlafion of carotin. 



In tlie experiments descrited in the previous paper, films of 

 carotin were exposed to light in a current of moist air. Using 

 watery emulsions of carotin exposed to light and air, the oxidation 

 was much more rapid than in the case of xanthophyll, the liquid 



