618 
Algin. 
Am.  Jour.  Pharm. 
Dec,  1883. 
for  sepaaating  the  iodine  and  salts.  Analysis  of  mixed  samples  of  the 
salts  yielded  the  following  results : 
Fucns  Laminnria 
vesiculosus.  stenophylla. 
Calcium  sulphate...                                  1-69  4'33 
Potassium  sulphate  11-29  23-62 
Potassium  chloride  19-90  13-71 
Sodium  chloride  60-96  58*20 
Magnesiun  chloride   4-35   
Sodium  carbonate  0*53   
Sodium  iodide                                         1-26  0*12 
99-98  99-98 
From  experiments,  it  is  demonstrated  that  the  extraction  is  practi- 
cally complete  after  four  macerations. 
The  sodium  carbonate  extract  is  evaporated,  and  the  residue  (the  algin 
combined  with  soda)  when  dry  resembles  gum  in  appearance,  but  can 
be  obtained  in  thin  transparent  flexible  sheets.  The  solution  is  slightly 
alkaline;  any  great  excess  of  sodium  carbonate  apparently  destroys 
the  algin,  whilst  excess  of  acid  gelatinizes  it  so  that  a  solution  of  only 
2  per  cent,  becomes  semi-solid  when  acidified.  A  solution  can  be  neu- 
tralized without  the  algin  being  precipitated.  The  solution  gives  the 
following  reactions  with  various  reagents.  Dilute  mineral  acids  gene- 
rally coagulate  it.  Boracic  acid,  however,  has  no  effect;  and  it  is  not 
affected  by  acetic,  formic,  citric,  tartaric,  or  benzoic  acids.  Barium,, 
calcium,  strontium,  copper,  zinc,  aluminium,  tin,  antimony,  cobalt,  and 
nickel  salts  all  precipitate  it.  Ferric  chloride  gives  a  dark  brown 
coagulum ;  mercurous  nitrate  forms  a  white  precipitate,  but  mercuric 
chloride  and  silver  nitrate  have  no  effect.  Both  basic  and  normal  lead 
acetates  give  white  precipitates.  It  is  unaffected  by  magnesium  salts; 
by  potassium  silicate,  dichromate,  ferrocyanide,  and  permanganate; 
and  by  sodium  borate,  tungstate,  stannate  and  succinate,  and  by  tannin. 
Concentrated  sulphuric  acid  dissolves  it;  concentrated  nitric  oxidizes  it^ 
oxalic  acid  being  amongst  the  products.  From  these  reactions  it  wnll 
be  seen  that  it  differs  from  all  similar  substances :  thus,  from  albumin 
by  not  being  coagulated  when  heated,  and  by  not  precipitating  silver 
nitrate;  from  gelose,  by  being  soluble  in  dilute  alkalis,  but  insoluble 
in  boiling  water,  gelose  is  just  the  reverse;  from  gelatin,  by  giving  no 
reaction  with  tannin;  from  starch,  by  not  reacting  with  iodine;  from 
dextrin,  etc.,  by  being  insoluble  in  dilute  alcohol  and  dilute  mineral 
