PROPERTIES AND METHODS OF IDENTIFICATION 239 



weight. The oxidizing pigment, has a peculiar odor, which is stated 

 by Willstatter and Escher (1910) to be different from that of oxidiz- 

 ing carotin or xanthophyll, but is not described. 



AY hen lycopin crystals are dissolved in a little OS, and much ether 

 and treated with one-third their weight of iodine, a lycopin iodide cor- 

 responding to the probable formula C 40 H,J, precipitates in the form 

 of dark green, gelatinous flakes, containing 34-37 per cent iodine. 

 AA'hen the lycopin crystals are treated with a trace of bromine vapor 

 they first turn a vivid green, and can then be dissolved in an excess 

 of bromine to form a colorless, resinous material, insoluble in an- 

 hydrous formic acid, whose constitution is somewhat difficult to un- 

 derstand in the light of the analyses made by Willstatter and Escher. 

 The combined addition and substitution compound appears to have 

 the constitution C 40 H 44 Br,, ; , indicating substitution of 12 hydrogen 

 atoms and addition of 14 bromine atoms. This would indicate a much 

 greater instability of the lycopin double bonds than is the case with 

 carotin which forms the bromide C 40 H 36 Br 22 , which shows the addi- 

 tion of only two atoms of bromine and corresponds to the di-iodide 

 which the pigment forms. 



Fucoxanthin. This carotinoid crystallizes from concentrated 

 methyl alcohol in the forms of long amber colored prisms, belonging 

 to the monoclinic system. The crystals are shown in Plate 2, Figure 

 6. The powdered crystals are brick red. These crystals contain three 

 molecules of methyl alcohol. When freed of the solvent by desicca- 

 tion, the crystals are hydroscopic. This water is difficult to remove, 

 being given up only at 105 C., under diminished pressure. Fucoxan- 

 thin crystallizes from dilute alcohol or acetone in characteristic hexa- 

 gon-shaped tablets, containing 2 molecules of water of crystallization. 

 The addition of water to the alcohol or acetone solution of fucoxan- 

 thin precipitates the pigment as needles which rapidly change to the 

 hexagon-shaped hydrates. The anhydrous crystals melt at 159.5- 

 160.5 C. (corrected), those containing methyl alcohol about 10 lower. 



Fucoxanthin resembles xanthophyll in its solubilities. One hun- 

 dred grams of boiling methyl alcohol dissolve 1.66 grams of pigment, 

 but only 0.41 grams at C. The crystals are fairly difficultly soluble 

 in ether, fairly easily in CS 2 , and easily in ethyl alcohol. The pure crys- 

 tals, either hydrates or methyl alcoholates, do not readily oxidize, but 

 the solutions readily bleach, and a product can be obtained from these 

 colorless solutions which corresponds to the formula C 40 H 54 16 or 



\-JAnklrA\JlA- 



