IkM.  Jour.  Pharm.  ] 
June  1,1871.  J 
Sulpho-carholates. 
265 
This  is  rather  a  long  description  of  wliat  in  practice  is  a  very  simple 
and  good  process,  the  three  principal  points  to  be  borne  in  mind 
il>eing, 
1st.  To  use  a  weak  solution  of  permanganate. 
2(\.  To  have  a  very  faint  pink  color  ns  a  standard  of  comparison. 
3d.  To  let  the  liquids  remain  after  agitation  together  10-15  minutes 
before  comparing  them. 
I  may  add,  that  it  is  very  remarkable  how  little  can  be  told  of  the 
•^alue  of  a  sample  of  cochineal  by  a  mere  physical  examination,  and 
that  the  frequent  inconsistency  between  value  and  price  is  equally 
surpri  ing.  I  have  known  samples  to  differ  thirty  per  cent,  in  color- 
Sog  power,  and  only  one  or  two  cents  per  pound  in  price. 
Laboratory^  59  Broad  street^  Boston. 
— Amer.  Chem.,  April,  1871. 
SULPHO-CARBOLATES. 
By  T.  H.  Hustwick. 
From  communications  to  this  and  other  journals  on  the  preparation 
'^>f  some  of  the  above  salts,  I  have  gathered  that  the  formation  of 
rsulpho-carbolate  of  zinc  is  best  accomplished  by  a  process  of  decom- 
rposition  or  displacement.  In  a  late  number  of  this  Journal  (No.  39) 
is  given  a  process  for  the  preparation  of  this  salt  by  decomposing  sul- 
■pko-carbolate  of  lead  by  metallic  zinc  ;  doubtless  the  salt  of  zinc  thus 
formed  is  of  great  purity,  but  is  it  not  possible  that  a  salt  of  equal 
>purity  may  be  obtained  by  direct  combination,  saving  both  time  and 
trouble  ?  My  own  experience  leads  me  to  suppose  that  it  may.  I 
liave  made  considerable  quantities  of  sulpho-carbolates,  and  the  modus 
-operandi  followed  by  me  has  been,  in  its  essentials,  that  recommended 
hj  Mr.  C.  H.  Wood  in  this  Journal  (Vol.  X.  2d  ser.  No.  7);  this  process, 
lAOwever,  gives  a  salt  more  or  less  colored  and  less  crystallized  than 
'when  pure.  Where  one  of  the  alkalies  or  alkaline  earths  is  the  base, 
Tiothing  more  is  required  than  to  evaporate  the  neutral  solution  so  far 
as  to  produce  a  good  crop  of  crystals  ;  these  are  to  be  well  drained 
and  redissolved  for  a  second  crystallization.  For  the  zinc  salt  I  have 
.saturated  tlic  diluted  acid  with  the  oxide,  evaporating  the  solution 
till,  when  quite  cold,  a  nearly  solid  mass  of  crystals  is  left  in  the 
■bottom  of  the  basin  ;  this  reddish-colored  magma  is  well  broken  up 
•and  allowed  to  rest  a  short  time,  when  the  supernatant  liquor  may  be 
