26  Practical  Notes  from  Foreign  Journals.        { '^""'jan^ss 
dark -green  color  is  produced  ;  if  only  one  or  two  coats,  and  afterwards 
heating  in  a  drying  oven,  different  colors  are  obtained,  according  to 
the  longer  or  shorter  exposure  to  heat  (light  or  dark  gold,  orange, 
brownish  red). — Polyt.  NotizbL,  xxxviii,  p.  172. 
Precipitation. — The  best  way  to  precipitate  is  not  to  pour  one  solu- 
tion into  the  other,  but  to  pour  both  simultaneously,  in  a  thin  stream, 
into  a  large  quantity  of  water. 
The  precipitates  obtained  in  this  way  are  not  only  in  an  exceedingly 
fine  state,  but  also  easy  to  wash  out  and  dissolve. 
If  the  two  solutions  differ  much  in  specific  gravity,  the  best  way  is 
to  let  the  heavier  run  in  near  the  top  of  the  water,  and  the  lighter 
near  the  bottom.  If  possible,  both  solutions  ought  to  be  brought  to 
the  same  bulk. — Dieterich,  Pharm.  Zeit.  RmsL,  xxiii,  p.  371. 
Honey. — Dieterich  finds  that  honey  kept  in  woods  very  soon  fer- 
ments, while  honey  from  the  same  batch  kept  well  in  glass  or  earthen- 
ware.— Pharm.  Zeit.  Russl.,  xxiii,  p.  385. 
Fixed  Oils,  Fats  and  Ointments. — Dieterich  strongly  recommends 
benzoinating  them ;  he  employs  at  least  10  per  cent,  benzoin,  although 
for  fiits  20  per  cent,  is  better.    Only  recently  rendered  fat  can  be  pre- 
served successfully  in  this  way  (and  all  ointments  made  w»th  it);  old  — 
and  partially  rancid  fats  are  not  preserved. — Ibid.,  xxiii,  p.  386. 
Bicarbonate  of  Sodium. — Dieterich  recommends  keeping  the  bicar- 
bonate in  a  cool  place  and  in  tightly  stoppered  containers,  since  it  is 
apt  to  lose  part  of  its  carbonic  acid,  and  thus  be  converted  into  mono- 
carbonate  if  exposed  to  the  air. — Ibid.,  p.  387. 
Saponimentum. — This  is  a  name  proposed  by  Dieterich  for  opodel- 
doc, and  he  gives  several  formulas.  Saponimentum  with  arnica;  Peru 
balsam  ;  carbolic  acid  ;  eucalyptus;  iodine;  iodine  and  sulphur;  iodo- 
form ;  tar;  sidphur;  storax ;  thymol. 
They  consist  of  stearin  soap,  olein  soap,  alcohol  and  the  respective 
medicinal  component. — Ibid.,  p.  389. 
Silver-plating  Solution. — Ebermeyer  dissolves  20  parts  of  silver  in 
60  parts  of  nitric  acid,  adds  20  parts  of  caustic  potassa,  50  parts  of 
distilled  water,  filters,  and  adds  sufficient  distilled  water  to  22*^  B.  (sp. 
gr.  1-176).  The  objects  are  cleaned  with  alkali,  etc.,  dried,  warmed, 
and  moved  backward  and  forward  in  the  solution;  they  are  then  dried 
with  saw-dust,  and  finished  with  precipitated  chalk  and  chamois. — 
Pharm.  Zeit.  Russl.,  xxiii,  p.  405. 
Cement  for  Brass  on  Glass  (for  instance,  petroleum  lamps). — 1  part 
