TUBERS  OF  THE  CHINESE  POTATO. 
261 
ANALYSIS  OF  THE  TUBERS  OF  THE  CHINESE  POTATO  (DIOS- 
COREA  BATATAS),  CULTIVATED  NEAR  PARIS  DURING  THE 
YEAR  1854. 
By  E.  Fremy. 
The  tubers  analysed  had  the  following  composition  : — 
Water 
Solid  mutters 
79-3  ^ 
'  Starch  ..... 
Cellulose  . 
Mineral  salts  .  . 
20-7  ■{  Albuminous  matter 
Fatty  bodies,  sugar,  soluble  principles 
100-0  t 
16-0 
1-0 
11 
1-5 
1-1 
20-7 
Cultivated 
Cultivated 
at  the  Museum. 
in  Algeria. 
13-1 
16-76 
24 
2-54 
0-2 
0-30 
04 
145 
1-3 
1-90 
82-6 
77-05 
M.  Boussingault  had  made  a  previous  analysis  of  tubers  grown 
at  the  Museum,  and  M.  Payen  of  tubers  from  xilgeria.  The 
following  are  the  results  of  these  analyses  : — 
Starch  and  mucilaginous  substance  . 
Albumen  and  other  azotized  matters  . 
Fatty  matters  .... 
Cellulose  ..... 
Mineral  salts  ..... 
Water  
By  comparing  these  results  with  those  of  the  analysis  already 
given,  it  will  be  seen  that  the  plants  cultivated  in  France  are 
actually  approaching  those  grown  in  Algeria.  The  proximate 
principles  of  which  the  tubers  are  composed  are  to  a  great  extent 
the  same  as  those  existing  in  the  potato. 
The  Chinese  potato  only  contains  16  per  cent,  of  starch, 
whilst  the  potato  may  furnish  20  per  cent.  ;  the  former,  however, 
possesses  a  very  remarkable  azotized  principle,  which  is  not  met 
with  in  the  potato,  and  which  may  exercise  a  favorable  influence 
upon  the  use  of  this  valuable  tuber.  The  mucilaginous  principle 
which  gives  its  unctuous  properties  to  the  juice  of  the  Dioseorea 
Batatas,  and  which  causes  the  pasty  consistence  assumed  by  this 
tuber  when  cooked,  differs  in  its  general  properties  from  the 
gummy  vegetable  substances,  and  approaches  albumen,  being 
azotized  and  coagulable  by  heat. 
This  body  must  not  be  confounded  with  that  which  is  often 
