368  Standardization  of  Solid  Extracts.  {Ami^yr;im&Tm' 
is  added  to  the  nearly  finished  extract,  it  suffers  but  slight  altera- 
tion in  consistence  even  when  kept  for  several  years;  of  course,  it 
must  be  kept  tightly  covered,  probably  one-half  of  the  deteriora- 
tion of  solid  extracts  being  due  to  neglect  of  this  precaution,  in 
which  case  loss  of  moisture  causes  the  extract  to  become  hard  and 
brittle  and  produces  a  corresponding  alteration  in  strength. 
A  list  has  been  prepared  of  the  average  yield  of  solid  extract 
obtained  in  actual  practice  from  those  official  drugs  to  which 
standardization  might  easily  be  applied ;  to  this  has  been  added,  in 
each  case,  the  average  percentage  of  alkaloid  present  in  the  drug, 
and  the  standard  to  which  the  solid  extract  should  conform  in 
alkaloidal  content. 
Extracts. 
Average 
Per  Cent, 
of 
Extract 
Obtained. 
Average 
Per  Cent, 
of 
Alkaloid 
Present  in 
the  Drug. 
Percentage  of 
Alkaloid 
Required  in 
a  Solid 
Extract  of 
Standard 
Strength. 
19 
0-50 
2-50 
Belladonna  leaves,  alcoholic  . 
20 
0-40 
2-oo 
26 
2-501 
io-oo1 
Colchicum  root  
25 
0-50 
2-00 
28 
0-50 
175 
20 
0-18 
0-90 
5 
0.20 
4-00 
Stramonium  seed  
20 
0'35 
175 
Standard  has  already  been  adopted. 
Standard  has  already  been  adopted. 
1  Percentage  of  quinine. 
In  aconite  root  the  percentage  of  extractive,  when  compared  with 
the  average  alkaloidal  content  of  the  drug,  shows  that  the  extract 
should  contain  about  2-50  per  cent,  of  aconitine,  estimated  gravi- 
metrically. 
