Pharmaceutical  Meeting. 
Am.  Jour.  Pharm. 
March,  1900. 
as  kid,  goat,  sheep,  etc.  The  leather  produced  in  this  way  is  insoluble  in  water, 
and  is  superior  to  bark-tanned  leather  in  the  respect  that  it  does  not  stretch. 
Its  superiority  to  alum  skin  lies  in  the  fact  that  it  can  be  washed  without  becom- 
ing like  parchment.  If  the  tawed  skins  are  taken  before  they  have  become  per- 
fectly dry,  they  may  be  readily  given  any  shade  of  color. 
The  methods  in  use  for  chrome  tanning  are  known  as  "one-bath"  and 
two-bath  "  processes.  According  to  the  first,  the  skins  are  subjected  to  the 
action  of  green  chromium  salts  at  once,  and  according  to  the  latter  they  are 
impregnated  with  chromic  acid  in  the  first  bath,  and  in  the  second  treated 
with  reducing  agents.  The  "two-bath"  process  is  considered  to  be  the 
more  valuable. 
A  number  of  two- bath  processes  other  than  the  Schultz  method  were  described 
by  the  speaker,  the  principal  difference  in  these  methods  being  due  to  the  use 
of  different  reducing  agents.  The  reduction  is  accomplished  with  :  alka- 
line sulphides  and  acid  (Norris  and  Little)  ;  (2)  hydrogen  sulphide  gas 
(Norris)  ;  (3)  hydrogen  dioxide  or  peroxides  (Sadtler)  ;  (4)  lactic  acid  (German 
patent  by  Bohringer)  ;  (5)  hydrosulphurous  acid  (Norris)  ;  (6)  nascent  hydro- 
gen, electrolytic  (Sadtler). 
The  principal  one-bath  processes  in  use  are  the  Martin  Dennis  and  that 
known  as  "  Eureka  Tannage."  In  the  first  a  solution  containing  chromium 
chloride  and  chromium  hydrate,  and  sold  under  the  name  of"  Tannolin,"  is 
used.  The  second  of  these  processes  was  patented  by  G.  W.  Adler  and  consists 
in  using  a  solution  of  chromium  chloride  or  sulphate  and  acetate  of  soda. 
The  speaker  remarked  in  this  connection  that  a  book  was  published  in  Ger- 
many two  years  ago  on  chrome  tanning  patents,  which  showed  that  three- 
fourths  of  these  patents  have  been  developed  in  the  United  States. 
One. of  the  most  recent  methods  for  coagulating  the  fibre  of  skins  is  that  in- 
volving the  use  of  formaldehyde.  Dr.  Charles  S.  Dolley,  of  Philadelphia,  who 
has  developed  this  method,  was  present,  and  was  asked  to  make  some  remarks 
on  it.  He  first  referred  to  the  use  of  formaldehyde  for  fixing  animal  and  vege- 
table tissues  in  microscopic  work,  and  said  that  its  property  of  acting  on  the 
collageen  of  animal  skin  renders  it  of  value  in  the  production  of  leather.  The 
advantages  claimed  for  this  leather  were  :  that  it  may  be  put  into  hot  or  cold 
water  without  becoming  hard  or  going  back  again  as  tawed  leather.  It  seems  to 
stretch  very  little  and  it  was  thought  that  perhaps  formaldehyde  is  a  better  fixing 
agent  than  chromic  oxide  ;  it  comes  out  of  the  formaldehyde  bath  almost  white 
and  is  perfectly  neutral  to  colors  ;  owing  to  its  suppleness  it  is  used  for  valves, 
etc.,  and  is  thought  to  be  more  uniform  in  texture  than  chrome  tanned  leather. 
It  was  also  stated  that  the  method  of  tanning  by  the  use  of  formaldehyde  has 
the  advantage  of  being  performed  in  a  comparatively  short  time.  The  principal 
drawbacks  to  this  method  are  the  disagreeable  properties  of  the  gas  and  its 
tendency  to  polymerize. 
Commenting  upon  Dr.  Dolley's  remark  in  regard  to  the  texture  of  chrome 
tanned  leathers,  Professor  Sadtler  said  that  in  order  to  produce  a  uniform  pro- 
duct the  process  of  reduction  must  be  thoroughly  carried  out  and  the  acid 
afterward  neutralized  by  an  alkaline  bath. 
Prof.  Jos.  P.  Remington  expressed  himself  as  being  very  much  pleased  with 
the  remarks  on  the  above  subject,  and  said  that  it  seems  strange  that  the 
achievements  pertaining  to  the  chemistry  of  this  industry  should  be  reserved 
