546  New  Method  of  Treating  Seaiveeds,  {^"nov'isss''""' 
by  alkalies  and  alkaline  salts,  starch,  glycerol  and  cane-sugar.  It  does- 
not  precipitate  the  ordinary  alkaloids.  It  is  distinguished  from  albu- 
men, which  it  most  resembles,  by  not  coagulating  on  heating,  and 
from  gelose  by  not  gelatinizing  on  cooling,  by  containing  nitrogen,  by 
dissolving  in  weak  alkaline  solutions,  and  being  insoluble  in  boiling 
water.  From  gelatin  it  is  distinguished  by  giving  no  reaction  with 
tannin ;  from  starch,  by  giving  no  color  with  iodine ;  from  dextrin, 
gum-arabic,  tragacanth  and  pectin  by  its  insolubility  in  dilute  alcohol 
and  dilute  mineral  acids. 
It  is  remarkable  that  it  precipitates  the  salts  of  the  alkaline  earths^ 
with  the  exception  of  magnesium,  and  also  most  of  the  metals;  but  it 
gives  no  precipitate  with  mercuric  chloride  or  potassium  silicate. 
COMMERCIAL  APPLICATIONS  OF  ALGIN,  OR  SODIUM  ALGINATE. 
For  Sizing  Fabrics. — As  a  finish,  algin  has  the  advantage  over 
starch  that  it  fills  the  cloth  better,  is  tougher  and  more  elastic,  that  it 
is  transparent  when  dry,  and  that  it  is  not  acted  upon  by  acids.  It  im- 
parts to  the  goods  a  thick  clothy,  elastic  feeling,  without  the  stiffness 
imparted  by  starch.  It  has  the  advantage  possessed  by  no  other  gum 
of  becoming  insolul)le  in  presence  of  a  dilute  acid  which  decomposes 
starch  or  dextrin.  No  other  gum  having  anything  like  the  viscosity 
of  algin  in  solution,  none  will  go  so  far  in  making  up  the  solution  or 
cover  such  a  large  surface.  The  alginate  of  alumina  in  caustic  soda  is 
a  stiff  dressing,  and  in  the  crude  unbleached  state  will  be  a  cheap 
dressing  for  dark  materials,  and  in  the  colorless  for  finer  fabrics.  The 
ammoniated  alginate  of  alumina  can  be  used  to  give  a  glossy  surface,, 
which  is  quite  insoluble  after  drying. 
As  a  Mordant  and  Dung-suhstitide  in  Dyeing  and  Printing. — Mr- 
John  Christie,  of  the  firm  of  J.  Orr  Ewing  &  Co.,  states  that  there 
is  another  application  of  the  alginate  of  soda,  viz.,  in  the  fixing  of 
mordants  such  as  those  of  alumina  or  iron  upon  cotton  fibre."  Very 
encouraging  results  are  said  to  have  been  obtained,  and  Mr.  Christie 
believes  a  very  large  application  will  be  found  for  alginate  of  soda  as 
a  "  dung-substitute.'^  This  being  the  case,  the  substitution  of  so  harm- 
less a  compound  for  one  so  poisonous  as  the  generally  used  arseniate 
of  soda  should  be  welcomed  and  a  fair  trial  accorded  the  new  dung- 
substitute.  In  Germany,  where  the  use  of  poisonous  materials  in  con- 
nection with  printing  and  dyeing  textile  fabrics  is  greatly  restricted,  if 
not  altogether  interdicted,  one  would  imagine  such  a  substitute  would 
