434  Recent  Literature  Relating  to  Pharmacy.  {^pfemberfS' 
RECENT  LITERATURE  RELATING  TO  PHARMACY. 
A  SUBSTITUTE  FOR  HYDROGEN  SULPHIDE  IN  ANALYSIS. 
Any  means,  whereby  the  unpleasant,  unstable  and  inconvenient 
hydrogen  sulphide  can  be  replaced  in  analytical  practice  attracts  the 
chemist;  hence  a  recent  article  on  the  subject  by  M.  Vogtherr 
(B.  d.  Dtsch.  Pharm.  Ges.,  1898,  228)  is  worthy  of  careful  attention. 
The  writer,  after  reviewing  the  various  suggested  substitutes  for 
hydrogen  and  ammonium  sulphides,  concludes  that  most  favorable 
for  this  purpose  are  the  sulphur  derivatives  of  carbonic  acid,  and 
shows  that  of  these  the  most  acceptable  are  such  as  have  the  sul- 
phur in  a  thio  (SH)  group.  The  best  of  these,  he  thinks,  is  ammo- 
nium di  thio-carbonate,  CO  (SNH4)2,  which  he  prepares  by  mixing 
five  parts  of  carbon  disulphide  with  nine  parts  20  per  cent,  ammonia 
in  a  glass-stoppered  bottle  and  shaking  at  ordinary  temperature  as 
long  as  carbon  disulphide  is  dissolved,  whereupon  the  excess  of 
ammonia  is  neutralized  with  hydrochloric  or  acetic  acid. 
The  product  is  an  orange-yellow  liquid,  of  scarcely  any  sulphide 
odor,  containing  10  per  cent,  to  12  per  cent,  ammonium  di  thiq- 
carbonate,  8  per  cent,  ammonium  chloride,  and  traces  of  ammonium 
sulpho-cyanate  and  ammonium  sulphide. 
If  necessary,  a  30  per  cent,  solution,  as  stable  as  ammonium  sul- 
phide, can  be  made.  Its  only  inconvenience  is  that  it  stains  the 
skin  brown. 
The  writer  gives  an  elaborate  report  on  the  action  of  the  reagent 
on  metals,  finding  its  behavior  almost  identical  with  that  of  hydro- 
gen sulphide. 
He  then  outlines  a  new  table  of  analysis,  covering  the  minor 
divergences  from  hydrogen  and  ammonium  sulphides.  Its  essential 
points  of  difference  from  the  usual  methods  of  analysis  (see  Sadtler 
and  Trimble,  Vol.  II)  are  noted  below.  In  this  statement  the  letter 
R  means  ammonium  dithiocarbonate  solution,  and  the  individual 
identity  reactions  are  omitted. 
After  precipitation  of  Pd.,  Ag.  and  Hg{ous)  by  hydrochloric  acid, 
the  scheme  continues  by  precipitating,  from  the  boiled  and  cold 
filtrate,  the  metals  Hg{ic).,  Bi,  Cd.,  some  Co.,  As.,  Cu.,  Sb.  and  Sn. 
by  R  instead  of  by  hydrogen  sulphide.  This  precipitate  is  warmed 
with  excess  of  reagent. 
A.  — Warm  R  does  not  dissolve  Hg.,  Br.,  Pd.,  Cd.  and  some  Co. 
B.  — Warm  R  dissolves  As.,  Cu.,  Sb.  and  Sn. 
