Am.  Jour.  Pbarm.) 
December,  1895.  J 
Tubular  Prismatic  Crystals. 
605 
developed  around  a  void  or  their  mother-liquor — have  ever  been 
seen,  at  least  never  reported. 
In  the  course  of  some  investigations,  I  obtained  a  growth  of 
hollow  crystals  of  monobromated  camphor.  I  have  often  crystal- 
lized the  above  substance,  but  never  before  nor  since  have  tubular 
crystals  been  formed.  To  me  they  were  full  of  curiosity,  having  in 
all  my  crystallographic  studies  never  seen  or  heard  of  hollow  crys- 
tals. Prof.  Pettee,  in  charge  of  mineralogy  at  the  University  of 
Michigan,  to  whom  some  crystals  were  sent,  reported  that  the 
specimens  sent  him  were  without  parallel  for  hollowness. 
The  tubular  crystals  were  obtained  as  follows  :  A  given  quantity 
of  crude  monobromated  camphor  was  dissolved  in  an  equal  weight 
of  hot  benzin,  one-fourth  a  smuch  animal  charcoal  added  as  there 
was  monobromated  camphor,  boiled  on  the  water-bath  for  about 
fifteen  minutes,  removed,  vigorously  rotated,  so  that  the  charcoal 
accumulated,  cone-shaped,  in  the  centre  of  the  bottom  of  the  flask, 
allowed  to  cool  and  crystallize  over  night.  The  crystals  radiated  in 
all  directions  from  the  cone-shaped  charcoal  (Fig.  j). 
The  tubular  structure  was  observed  by  the  mother-liquor  retreat- 
ing from  the  hollow  of  the  crystals  while  drying  them  on  filter- 
paper. 
The  prismatic  crystals  belong  to  the  monoclinic  system ;  vary  in 
length  from  2-5  to  4-2  centimeters;  in  width,  from  3  to  46  milli- 
meters, and  in  thickness,  from  1-5  to  3-1  millimeters.  The  cross- 
sections  of  the  crystals  as  well  as  the  cross-sections  of  the  orifices 
are  rhombs.  The  free  ends  of  the  crystals  are  terminated  by 
single  planes,  inclined  about  45  °.  A  few  crystals  are  terminated 
by  two  planes,  one  large  and  one  small  plane,  forming,  nearly, 
a  right  angle  with  each  other.  The  supporting  ends  of  the  crystals 
are  somewhat  constricted,  on  account  of  the  crystal  aggregate, 
tapering,  in  several  instances,  on  the  narrow  sides,  for  several  centi- 
meters. This  distortion  of  the  crystal  destroys  the  symmetry  of 
hollow  as  well  as  that  of  the  crystal. 
Fig.  4.  represents  the  various  crystals  in  cross-section  and  side 
views. 
305  Cherry  Street, 
Philadelphia,  Pa. 
