A mMarU,r'i87h9!rm  I     Solution  of  Per  chloride  of  Iron.  141 
gent  power  is  much  lessened  by  the  large  proportion  of  water  it  con- 
tains. The  latter  fault  is  partly  concealed  by  making  it  excessively 
alkaline;  it  is  then  corrosive,  and  attacks  and  destroys  the  skin,  color- 
ing matters  and  woolen  and  silken  goods.  Analysis  reveals  the  pres- 
ence of  the  decomposition  products  of  the  latter  in  the  water  in  which 
they  have  been  washed.  Silicate  of  soda  with  fecula  is  far  the  most 
injurious  adulterant  of  soap, and  it  is  also  the  one  most  usually  employed. 
Almost  all  commercial  soaps  contain  it.  Silicate  of  soda  in  small 
quantities  does  not  alter  the  appearance  of  the  soap;  but  it  is  decom- 
posed when  used,  and  silica  is  deposited  in  the  fibre  of  the  flax  or 
cotton  and  cannot  be  removed,  rapidly  destroying  the  tissues.  Silk 
and  wool  are  also  attacked,  and  made  more  liable  to  be  destroyed  by 
alkalies.  Water  in  which  silk  and  wool  have  been  washed  with  this 
soap  contains  considerable  quantities  of  sulphur  and  ammonia,  result- 
ing from  the  decomposition  of  the  material.  According  to  Dr.  Vohl, 
linen  and  cotton  cloths  thus  treated  look,  under  the  microscope,  like 
worn  fabrics — the  fibre  destroyed  and  the  surface  covered  with  a  nap. 
Franklin  said  good  bargains  are  sometimes  ruinous.  This  is  particu- 
larly true  of  soaps.  Low-priced  samples  are  never  cheap;  a  larger 
quantity  must  be  used  to  cleanse  an  equal  amount,  and  fabrics  are  far 
more  rapidly  destroyed." — Scient.  Amer^  Jan.  18,  1879. 
NEW  MODE   OF  PREPARING   SOLUTION  OF  PER- 
CHLORIDE  OF  IRON. 
By    E.    B.    S  h  u  t  t  l  e  w  o  rt  h  . 
The  preparation  of  solution  of  perchloride  of  iron  is  always  a  disa- 
greeable operation,  and,  on  the  large  scale,  especially  so.  The  addition 
of  nitric  acid  to  the  acid  ferrous  chloride  requires  to  be  made  very 
carefully,  and  the  operator  must  give  it  all  his  attention,  else  the  rapid 
disengagement  of  nitric  oxide  may  cause  loss  by  foaming.  The  ordinary 
directions  require  the  operation  to  be  conducted  at  a  temperature  con- 
siderably above  that  of  boiling  water,  and  a  vessel  capable  of  bearing 
the  heat  of  a  sand-bath  and  of  withstanding  the  most  trying  of  acids  is 
requsite. 
If  the  plan  proposed  some  years  ago  by  Mr.  R.  Rother  (using  chlo- 
