AmjUn°e?ri887harm*}    Practical  Notes  from  Various  Sources.  293 
Mixtures  of  equal  weights  of  sulphuric  acid  attain  in  six  clays  the 
limit  of  change,  corresponding  to  12*1  per  cent.  H2S04  in  neutralizing 
power.  A  mixture  of  1  part  of  sulphuric  acid  and  5  parts  of  alcohol 
forms  in  about  ten  months,  sulphovinic  acid  corresponding  in  neutral- 
izing power  to  5  per  cent.  H2S04. 
Liquor  Ferri  chloridi. — The  commercial  article  was  found  by  Geo. 
Buchner  (Chemiker  Ztg.,  1887,  p.  417)  to  be  often  contaminated  with 
arsenic,  probably  as  arsenic  acid  or  ferric  arsenate.  The  pharmaco- 
poeias do  not  give  a  test  for  this  impurity,  which  is  readily  detected 
by  treating  a  small  quantity  of  the  liquor  with  zinc  and  hydrochloric 
acid,  when  the  hydrogen  gas  will  produce  a  yellow,  brown  or  black 
color  upon  paper  moistened  with  silver  nitrate.  Ferric  compounds, 
prepared  from  such  a  liquor,  will  likewise  contain  arsenic. 
In  testing  for  arsenic  by  Marsh's  process  the  author  directs  attention 
to  the  necessity  of  heating  the  reduction  tube  sufficiently,  since  by  the 
use  of  a  Bunsen  burner  an  arsenical  mirror  will  be  readily  obtained, 
while  with  the  same  materials  the  mirror  may  not  make  its  appear- 
ance on  prolonged  heating  with  a  Berzelius'  spirit  lamp. 
Ichihyol. — A.  tarry  product  is  obtained  by  the  dry  distillation  of  a 
bituminous  mineral  containing  fossil  fish  ;  on  treating  this  with  sul- 
phuric acid  and  subsequently  neutralizing  with  sodium  carbonate,  ich- 
thyosulphate  of  sodium  is  obtained,  known  also  as  ichthyol ;  it  is  tar- 
like in  appearance,  has  a  bituminous  odor,  on  heating  becomes  charred 
and  acquires  the  odor  of  liver  of  sulphur.  Its  aqueous  solution  is 
almost  neutral,  turbid,  brown  and  has  a  green  fluorescence ;  it  dissolves 
2)artly  in  alcohol  and  in  ether,  but  is  completely  soluble  in  a  mix- 
ture of  the  two  solvents  and  in  benzol,  and  is  almost  insoluble  in  pe- 
troleum-benzin.  It  has  been  used  internally,  the  odor  being  partly 
covered  with  coumarin  or  vanilla,  but  mostly  externally  in  rheuma- 
tism, erysipelas,  burns,  swellings  and  in  various  eruptions  of  the  skin ; 
the  ointment  made  with  petrolatum,  contained  from  2  to  50  per  cent, 
of  ichthyol.  Unna  administered  it  to  adults  in  doses  of  1  to  2  gm., 
and  favors  its  internal  use  in  all  affections  of  the  skin. 
Absorbent  wool,  a  by-product  in  the  manufacture  ol  wool-fat  or 
lanolin,  is  coming  into  use  as  a  substitute  for  absorbent  cotton,  over 
which  it  is  said  to  have  the  advantage  of  greater  absorbing  power  for 
liquids,  and  of  much  greater  elasticity. 
Mercuric  phenate,  C6H5.OHg.OH,  is  prepared  by  precipitating 
in  aqueous  solution  271  parts  of  mercuric  chloride  with  132  parts  of 
