Apr, 15, 191S 



Organic Constitiients of Kelps 



49 



pounds) of the pentosan type, with cellulose possibly making up a part of 

 the complex. Algin has weakly acid properties, forming soluble com- 

 pounds with the alkali metals. Thus, the sodium alginate precipitated 

 by alcohol is easily soluble in water, while the alginic acid is almost insolu- 

 ble in water. To precipitate out the alginic acid requires apparently a 

 definite concentration of the hydrogen ion. No precipitation occurs 

 with the weakly dissociated organic acids unless present in excess. From 

 an acetic-acid solution of algin, gelatinous precipitates may be obtained 

 with a large number of metallic salts. Mr. L. L. Lieb, of this laboratory, 

 has prepared a series of such compounds, as described in Table V. 



Table V. — Metallic alginates 



SOLUBLE ALGINATES (PRECIPITATED BY ALCOHOL)" 



Metal. 



Li... 



Na... 

 Mg.. 

 NH4. 

 K. .. 



Metallic salt used. 



Color of fresh 

 precipitate. 



Li (acetate) I Silver white. 



NaOH White 



Mg (acetate) ] do 



NH4OH Light yellow. 



KOH j Transparent. 



General properties of precipitate. 



Gelatinous, transparent. 

 " Stringy, ' ' brittle when dry. 

 Transparent, gelatinous. 

 Light, gelatinous. 

 Light, fluff }\ 



INSOLUBLE ALGINATES (PRECIPITATED FROM ACETIC-ACID SOLUTION) 



Al. 



AlCl, 



Ca i CaCl2 



Cr ! Cr(N03)3 



Mn Mn(C2H302)2. 



Fe'' FeS04.7H20. 



Fe'^' i FeClj 



Co I Co(N03)o 



Ni. 

 Cu. 

 Zn. 



NiClo.. 

 CUS64. 

 ZnS04. 



Sr j Sr(N03)2. 



Ag j AgNOs-.. 



Cd Cd(N03).,. 



Sn'^ SnCLHjO. 



Sn^^^^ ! SnCi; 



Ba I BaCL 



Pt.b PtCl4 



Au.& i AuClg 



Hg^ i Hg2(N03)2.. 



Pb Pb(CoH302)o . 



Bi Bi(N03)2 



U U(S04)2.4H20 . 



White 



...do.... 

 Light blue 

 Light red . 



Light brown 



Brown 



Reddish . . . . 



Light green 



do 



Colorless. . . 



Light brown 

 White 



Colorless 

 White... 

 .. ..do.. 



when dry, 



White. 

 Yellow 



Gelatinous, brittle 



brown color. 

 Gelatinous, glossy when drJ^ 

 Heavy, nongelatinous. 

 Gelatinous, good gloss to paper 



when dry. 

 Gelatinous, brittle when dry. 

 Gelatinous. 

 Gelatinous, good gloss to paper 



when dry. 

 Gelatinous. 



Do. 

 Gelatinous, silvery- gloss to paper 



when dry. 

 Heavy gelatinous, transparent 



when dry. 

 Gelatinous, becomes dark red 



when dn,-. 

 Gelatinous, becomes horny. 

 Thick, gelatinous. 

 Do. 

 do i Gelatinous, good gloss to paper 



when dry. 

 Gelatinous. 



Do. 

 Dense, white, gelatinous. 

 Gelatinous, like isinglass when 



dry. 

 Gelatinous. 

 Thick, gelatinous. 



Light brown 



Red 



White 



Colorless. . . . 



« All these soluble alginates give more or less gloss to paper. *> Precipitated from alcohol solution. 



