Analyses  of  Amemcan  Plants.  389 
ANALYSES  OF  AMERICAN  PLANTS. 
Abstracts  from  Theses. 
Rhus  glabra. — Mainly  with  the  view  of  determining  the  amount 
of  tannin  present  at  different  periods,  Jos.  A.  Palen,  Ph.  G.,  collected 
two  lots  of  leaves,  July  loth  and  August  30th,  from  plants  growing 
on  the  bluffs  bordering  the  Mississippi  river  near  Dubuque,  Iowa. 
These  were  dried  and  powdered,  and  yielded  the  following  analyti- 
cal results: 
July. 
August. 
5-72 
5-12 
•2 
1-5 
4-02 
•1 
1-22 
3-8 
5-6 
4-85 
1-3 
1-55 
14-3 
13-6 
10-8 
3-5 
10-1 
3^5 
10-92 
12-15 
•87 
•18 
3-  04 
4-  78 
•63 
•21 
4^2 
6-35 
13-29 
12-05 
6-21 
5-6 
Extracted  by  HCl  
4-72 
5-54 
3-36 
3-87 
6-72 
1^41 
4-6 
■34 
25-2 
9-17 
3-76 
4-4 
•34 
27-84 
Ash  
A  separate  estimation  of  tannin  was  made  by  precipitating  the  de- 
coction of  the  leaves  with  gelatin,  and  multiplying  the  weight  by 
0.54.  The  July  lot  yielded  16*36  per  cent.,  the  August  lot  15*75  per 
cent.  The  tannin  strength  of  both  samples  is  practically  alike,  but  is 
not  so  large  as  that  of  sumac  leaves  from  Virginia,  which  yield  from 
20  to  25  per  cent. 
The  cgloring  matter  exists  in  very  small  amounts,  and  is  probably 
alike  with  that  of  quercitron  bark.  The  ethereal  and  alcoholic  ex- 
tracts of  the  leaves  were  examined ;  cloth  prepared  with  different 
mordants,  like  ferric  acetate,  stannous  chloride,  copper  sulphate,  potas- 
