CRYSTALS  IN  THE  BARK  OF  GUAIACUM. 
47 
wards  the  end  of  the  distillation,  J  oz.  of  a  liquid  of  the  spec, 
grav.  of  chloroform,  but  having  the  odor  of  valerianate  of  oxide 
of  amyle ;  it  was  probably  formed  by  the  oxidation  of  the  fusel 
oil  of  the  alcohol.— Archw  d.  Ph.  1859,  Aug.  149.* 
Oxidation  by  Qhromic  Acid. — Frederking  (Arch.  d.  Ph.  1859, 
Aug.  150,)  has  observed,  that  all  carbohydrates  (sugar,  starch, 
&c.)  are  decomposed  by  chromate  of  potassa  and  a  sufficient  quan- 
tity of  sulphuric  acid,  into  carbonic  acid  and  water.  Oxalic,  tar- 
taric, citric  and  other  polybasic  acids  are  likewise  oxidized  by  this 
reagent ;  the  carbon  is  calculated  from  the  carbonic  acid,  the 
oxygen  of  which  is  deducted  from  the  whole  amount  of  oxygen 
given  off  by  the  chromic  acid  ;  the  difference  has  been  used  for 
the  oxidation  of  the  hydrogen  ;  the  weight  wanting  on  the  whole 
substance  is  oxygen.  Acetic,  formic  and  monobasic  acids  in 
general  yield  no  carbonic  acid. 
ON  THE  CRYSTALS  IN  THE  BARK  OF  GUAIACUM. 
By  Dr.  Otto  Berg. 
A  large  number  of  very  small,  colorless,  and  bright  crystals 
maybe  observed  by  means  of  a  magnifying  glass,  upon  the 
inner  surface  of  the  bark  of  guaiacum,  which  therefrom  receives 
a  peculiar  lustre.  Guibourt  declared  them  to  be  benzoic  acid. 
Richard  and  Trommsdorff,  however,  crystallized  resin  of  guaia- 
cum, of  which  the  bark  contains  about  2-5  per  ct.  In  Liebig 
and  Woehler's  Handwoerterbuch,  there  is  a  paper  on  guaiacum 
by  Dr.  Stadeler,  who  thinks  it  not  improbable  that  the  crystal- 
lized body  might  be  the  guaiacin,  observed  by  Landerer  in  the 
sediment  of  a  tincture  of  guaiacum.  I  have  pointed  out  this 
error  already  in  the  first  edition  of  my  Pharmacognosy,  where  I 
stated  that  these  crystals  were  of  inorganic  nature,  and  nothing 
else  but  gypsum.  Later  works,  however,  have  repeated  those 
old  assertions,  and  I  feel  myself  thereby  induced  to  enter  in  this 
place  more  into  details  on  this  subject. 
These  crystals  are  found  not  only  upon  the  inner  surface  of 
the  bark,  but  are  evenly  distributed  throughout  the  whole  inner 
*  The  same  substance  was  noticed  in  chloroform  by  Mr.  Henry  Pember- 
ton,  see  Amer.  Jour.  Phar.,  1853,  page  113.-— Editor. 
