66       .  Boy^oGitrates  and  their  Preparation, 
By  the  solution  in  boiling  water  of  the  constituents  according  to  the 
following  proportions  by  weight  these  salts  can  be  easily  obtained.  As 
with  the  exception  of  the  potassium  compound  the  borocitrates  crystal- 
lize badly  or  mostly  not  at  all^  the  preparations  are  produced  in  scales 
or  more  suitably  in  the  powder  form. 
The  following  are  the  proportions  by  weight  given  by  the  author : 
a.  Magnesium  Triborocitrate  (C^H507)2Mg3  4-(B3H30g)2.  —  Crystal- 
lized boric  acid^  35  parts ;  carbonate  of  magnesium,  25  parts,  or  calcined 
magnesia,  12  parts;  crystallized  citric  acid,  42  parts. 
h.  Magnesium  Dibot^ocitrate  (CgHgO-)2Mg2  +  (6211204)2. — Crystal- 
lized boric  acid,  24  parts  ;  carbonate  of  magnesium,  16  parts,  or  calcined 
magnesia,  8  parts ;  crystallized  citric  acid,  42  parts. 
c.  Magnesium  Monoborocitrate  (CgHy07)2Mg  +  (BH02)2. — Crystal- 
lized boric  acid,  24  parts;  carbonate  of  magnesium,  16  parts,  or  calcined 
magnesia,  8  parts ;  crystallized  citric  acid,  80  parts. 
Two  preparations,  Avhich  have  already  been  used  in  therapeutics, 
have  been  analyzed  by  the  author.  The  first,  obtained  from  Opper- 
nian's  pharmacy  in  Revel,  has  been  prepared  during  many  years  from 
an  old  prescription.  The  powder  is  soluble  in  20  parts  of  cold  water, 
but  less  soluble  in  hot  water,  and  after  cooling  there  is  a  separation  of 
crystals  of  boric  acid.  The  taste  is  strongly  acid,  and  in  composition 
it  stands  nearest  to  the  monoborocitrates,  but  it  contains  more  boric  acid 
than  can  become  chemically  combined.  The  mean  percentage  compo- 
sition was:  citric  acid,  61'64;  magnesium,  6*23;  boric  acid,  32*13. 
The  second  preparation,  also  from  the  above  pharmacy,  was  obtained 
from  Schering,  of  Berlin.  The  beautiful  silky  scales  are  soluble  in 
-equal  parts  of  cold  water.  According  to  the  proportions  of  the  citric 
acid  and  magnesium  it  might  be  described  as  a  diborocitrate,  but  for 
this  it  contains  somewhat  too  little  boric  acid.  It  consists  of  citric  acid 
73*50  per  cent.;-  magnesium,  8*83  per  cent.;  boric  acid,  16*67  per  cent. 
Lithium  Boeocitrates. — All  three  lithium  compounds  are  easily 
soluble  in  water,  and  what  was  stated  respecting  the  preparation  of  the 
magnesium  salts  applies  equally  to  them.  As  a  starting  point  of  the 
preparation  carbonate  of  lithium  is  the  most  suitable. 
Lithium  Triborocitrate  (CgHgLigO^  B3H30g). — Crystallized  citric 
acid,  20  parts;  lithium  carbonate,  11  parts;  crystallized  boric  acid,  18 
parts. 
b.  Lithium  Diborocitrate  (CgH4Li2(BO)20-.)  -j-  2H2O. — Crystallized 
