AmMJarch•,^>898rm•}     The  Rhubarbs  and  a  Probable  Adulterant.  135 
stronger  alkalis  did  not  afford  satisfactory  results,  since  they  formed  a 
gelatinous  mass  with  the  powders  that  did  not  show  the  colors  well. 
Briefly,  then,  the  author's  results  indicate  the  following  facts,  viz : 
That  the  characteristic  elements  of  the  powdered  rhubarb  are  the 
starch  grains,  calcium  oxalate  crystals,  and  massed  acicular  crystals 
of  chrysophanic  acid,  and  that  these  are  so  similar  in  the  two  forms 
that  no  point  of  distinction  is  offered  by  them.    Also,  that  the  reac- 
FiG.  7. — Rumex  Hymenosepalus.    x  450  diameters,    a,  starch  ;  b>  fragments 
of  pitted  vessel ;  c,  parenchyma  cells. 
tion  to  ammonia  serves  as  a  means  of  identifying  the  pure  specimens, 
but  not  mixtures.  And,  finally,  that  adulteration  with  canaigre 
may  be  detected  by  the  presence  of  the  characteristic  long  starch 
grains. 
Before  making  any  suggestions  as  to  the  manner  in  which  the 
text  of  the  U.S. P.  describing  rhubarb  may  be  changed  so  that  pow- 
dered rhubarb  may  be  clearly  identified,  the  author  desires  to  make 
further  study  of  the  subject.  He  would  gladly  receive  the  co-op- 
eration in  this  work  of  any  who  are  interested. 
Selenium  has  recently  been  employed  for  producing  colored  glass.  Rose- 
tinted  glass  is  made  by  adding  selenium  directly  to  the  ingredients  in  the  melt- 
ing-pot, the  depth  of  tint  depending  on  the  quantity  used  and  upon  the  char- 
acter of  the  glass — whether  hard  or  soft. 
