Am.  Jour.  Pharm. 
Nov.,  1890. 
Some  American  Galls. 
563 
SOME  AMERICAN  GALLS. 
By  Henry  Trimble. 
Contribution  from  the  Chemical  Laboratory  of  the  Philadelphia  College  of  Pharmacy. — 
No.  78. 
Read  at  the  Pharmaceutical  Meeting,  October  21. 
During  the  past  summer  a  number  of  galls  were  obtained  from 
the  oaks  and  sumacs  in  the  vicinity  of  Philadelphia.  During  July  a 
sample  was  collected  from  the  leaves  of  young  white  oaks,  Quercu's 
alba.  They  were  about  the  size  of  a  pea  and  characterized  by  a 
covering  of  purple  spines.  They  were  identified  by  Mr.  L.  O. 
Howard,  acting  entomologist  in  the  U.  S.  Department  of  Agri- 
culture, as  having  been  produced  by  the  insect  Acraspis  erinacei. 
They  were  submitted  to  a  partial  analysis  at  once  and  found  to  con- 
tain 17-89  per  cent,  of  tannin.  This  was  the  mean  of  three  closely 
agreeing  determinations  by  the  gelatin  and  alum  process.  The 
moisture  was  found  to  be  45-95  per  cent.,  and  ash,  o-6o  per  cent. 
In  order  to  compare  the  amount  of  tannin  and  ash  with  some 
further  work  on  the  subject,  the  following  figures  representing  the 
amount  of  each  in  the  absolutely  dry  substance  are  given — tannin, 
32-10  per  cent.;  ash,  i-ii  per  cent. 
Another  gall  very  common  in  this  vicinity  is  found  on  the  twigs 
of  the  white  oak.  They  are  round,  smooth,  of  a  waxy  lustre,  and 
much  resemble  very  small  apples,  but  they  are  not  quite  so  large 
as  the  Turkish  galls.  A  large  number  of  these  were  collected  in 
August,  and  identified  by  Mr.  Howard  as  "  a  Dipterous  gall,  made 
by  some  species  of  Cecidomyia  or  Diplosis."  They  were  found  to 
contain  73-19  per  cent,  of  moisture,  0-46  per  cent,  of  ash,  and  as  an 
average  of  three  determinations  9-34  per  cent,  of  tannin.  This 
corresponded  to  34-83  per  cent,  tannin  and  1-71  per  cent,  ash  in  the 
absolutely  dry  galls.  Some  experience  with  these  galls  in  previous 
years  had  led  me  to  a  knowledge  of  the  fact  that  when  they  were 
collected  and  allowed  to  air  dry  slowly,  they  rapidly  deteriorated 
in  tannin  strength.  It  was  on  this  account  that  all  of  the  galls 
above  mentioned  were  assayed  as  soon  as  collected,  although  one 
lot  was  rapidly  dried  at  a  temperature  of  100°,  and  then  set  aside 
for  some  weeks,  when  they  were  found  to  contain  the  same  per- 
centage of  tannin,  when  calculated  for  absolutely  dry  material,  as 
those  just  mentioned,  and  a  number  of  them  were  finely  powdered 
