890 
HYDRARGYRUM  CUM   CRETA,  ETC. 
By  using  a  weighed  quantity  of  the  powder,  and  by  weighing 
the  dried  precipitates  as  subchloride,  and  sulphide,  (rather  than 
as  ammoniated  mercury,)  and  by  distilling  the  mercury  from  the 
residue  into  alcohol,  and  drying  and  weighing  it,  this  process  is 
readily  converted  into  a  practically  sufficient  quantitative  analy- 
sis. This  is  the  method  adopted  in  the  examination  of  the  fol- 
lowing specimens  of  Hydrarg.  cum  Greta. 
Five  of  the  specimens  were  purchased  at  respectable  central 
prescription  stores,  and  the  sixth  is  the  specimen  mentioned 
above,  as  having  been  exposed  to  light  and  air  during  twenty- 
eight  months,  in  a  narrow  vial,  after  prolonged  trituration. 
The  product  of  the  officinal  formula  yields  on  analysis  not 
37.5  per  cent,  of  mercury,  as  it  should  do  in  theory,  but  only 
about  36.9  per  cent,  or  .6  per  cent,  minus.  This  deficiency  is 
probably  due  to  evaporation  during  the  process. 
SAMPLE 
1st.  Color  and  appear- 
ance good,     -    -  - 
2d.  Color  and  appear- 
ance good,  - 
3d.  Color  and  appear- 
ance pretty  good, 
4th.  Color  very  light, 
large  globules  visible, 
5th.  Color  light,  green- 
ish tinge,  - 
6th.  Color  very  dark, 
appearance  good, 
PERCENTAGE  OF 
Hg. 
HgaO. 
Hg  O. 
Ca  O,  C02 
Insoluble 
matter. 
Deficiency 
in  Hg. 
32.07 
0.08 
0.20 
63.29 
4.36 
14.50 
35.52 
0.33 
0.21 
63.94 
traces 
5.30 
35.44 
0.05 
54.79 
9.72 
5.5 
37.42 
0.12 
56.49 
6.67 
0.21 
28.08 
0.13 
0.22 
60.55 
11.02 
25.13 
34.2 
1.21 
1  44 
63.15 
traces 
The  result  of  these  examinations  does  not  justify  the  conclu- 
sions at  which  the  writer  had  arrived,  nor  does  it  explain  the 
cause  of  the  complaints  so  generally  made  by  physicians,  since 
that  sample  which  contained  most  of  both  oxides  failed  to  pro- 
duce the  bad  effects  complained  of.  The  proportion  in  this 
sample  is  still  very  small,  however,  and  nothing  like  what  other 
observers  have  found  ;  and,  therefore,  as  these  six  specimens 
can  scarcely  represent  the  market  upon  which  the  complaints 
