210 
ON  SPECIFIC  GRAVITY  OF  ALCOHOL. 
by  which,  when  the  temperature  and  the  specific  gravity  are* 
known,  the  per  cent,  of  commercial  alcohol  can  be  known,  I 
think  it  will  be  valuable  information. 
A  table  containing  such  information  must,  of  course,  in  addi- 
tion to  the  specific  gravity  of  each  per  cent,  of  alcohol,  state 
whether  the  per  cent  be  in  weight  or  in  measure  or  volume.  I 
am  quite  sure  that  the  table  in  the  U.  S.  Dispensatory  under  the 
head  of  alcohol,  i3  not  the  standard  by  which  the  distillers'  in- 
struments here  are  made.  I  this  day  weighed  a  sample  of  alco- 
hol, which  I  bought  for  80  per  cent.,  at  the  temperature  of  60°. 
It  is  0*834.  Now,  by  the  IT.  S.  Dispensatory,  it  is  nearly  8-5' 
per  cent,  by  weight,  and  by  Ure's  tables  nearly  90  per  cent,  by 
measure,  of  alcohol. 
I  think  it  would  be  desirable  to  know  the  U.  S.  Custom  House 
standard  for  first,  second,  third  and  fourth  proof  spirits,  and 
what  is  meant  by  so  much  above,  or  below  proof ;  in  other  words, 
what  are  the  respective  specific  gravities  of  these  spirits. 
If  there  be  no  standard  based  on  the  action  of  Congress,  per- 
haps the  usage  of  those  who  make  the  hydrometers  for  the  Cus- 
tom House  could  be  obtained  and  published.  At  all  events,  it 
seems  to  be  very  desirable  for  me,  if  I  am  about  to  purchase  a 
pipe  of  brandy  of  a  given  proof,  or  a  barrel  of  alcohol  of  any 
given  per  cent.,  in  a  distant  part  of  the  country,  to  know 
what  specific  gravity  I  am  entitled  to  receive.  *  *  *  *  * 
Yours  respectfully,  Charles  Mead. 
[On  receiving  the  above  letter,  although  we  had  at  command  Prof.  Mc- 
Cullogh's  valuable  "  Report,"  we  preferred  to  refer  it  to  Mr.  Sharp,  o£ 
Baltimore,  whose  judicious  remarks  before  the  Association  had  called  it 
forth. — Editor.] 
Baltimore,  April  4th,  |KM>. 
Mr.  AT.  Puocter,  Jr. 
Dear  Sir, — In  reply  to  the  inquiry  whether  there  is  a  United 
States  standard  for  estimating  the  strength  of  spirits,  I  will  say 
there  is  a  very  complete  and  reliable  calculation  made  by  Prof. 
R.  S.  Mc  Cull  oh,  and  under  the  superintendence  of  Prof.  A. 
Bache,  U.  S.  Coast  Survey  Office. 
The  title  of  the  two  works  punished  by  order  of  Congress  are 
as  follows  :  "  Report  of  the  Computation  of  the  Manual  of  Tables 
