210 
Strength  of  Alcoholic  Menstrua, 
(  Am.  Jour.  Pharm. 
X      May,  1882. 
strong.  It  is  true  that  in  practice  this  error  offsets  that  arising  from 
deficiency  in  the  strength  of  the  commercial  spirit,  but  where  exact- 
ness is  desired  neither  error  must  be  allowed  to  take  its  chance  of 
correction  in  this  way.  Hence,  in  the  table  there  Avill  be  found  the 
proportion  by  volume — or  by  weight,  as  the  case  may  be — of  water 
that  should  be  added  to  a  given  volume  of  alcohol  of  94  per  cent, 
(at  60° F.)  to  produce  any  required  mixture. 
Even  where  the  fluids  are  weighed,  it  is  often  desired  to  make  up  a 
certain  volume  of  menstruum,  and  it  is  to  facilitate  the  calculation  in 
such  cases  that  the  fourth  column  in  the  table  is  added.  It  is  required, 
e.  g.,  to  make  one  liter  of  a  mixture  which  shall  contain  25  per  cent, 
by  weight  of  absolute  alcohol.  By  the  table  it  appears  that  such  a 
mixture  will  consist  of  about  700  cc.  of  distilled  water  and  323  cc.  of 
94  per  cent,  alcohol.  The  equivalent  of  the  first  may  be  taken  as 
700  grams ;  that  of  the  latter  is  given  in  the  table  as  265  grams. 
[The  figures  given  are  obtained  from  the  table,  of  course,  by  interpola- 
tion, but  if  such  a  trifling  mathematical  operation  seem  formidable  to 
any,  the  nearest  figure  in  the  table  may  be  used  as  giving  a  close 
approximation  to  the  desired  amounts.] 
Correction  for  Temper atwre. — If  mixtures  of  alcohol  and  water  are 
to  be  made  by  volume  at  a  temperature  above  or  below  60°F.,  a  cor- 
rection must  be  made,  the  volume  of  the  alcohol  being  increased  by 
of  1  per  cent,  for  each  27 °F.  in  excess  of  60°,  or  diminished  in  a 
similar  ratio  if  below  60°. 
Specific 
Gravity 
at  60°F. 
100  Volumes  contain 
Alcohol  1  Water 
of  94  p.  c!  ^^^^1- 
(Vol.)    1  (Vol.) 
Weight  of 
94  per  ct. 
Alcohol 
in  Col. 
II. 
Per  cent, 
by  weight 
of  94 
per  cent. 
Alcohol. 
100  Vols. 
contain 
Absolute 
Alcohol 
(Vols.) 
Per-cent. 
by  weight 
of 
Absolute 
Alcohol. 
•9986 
1^ 
99-04 
0-82 
-82 
-94 
•75 
•9972 
2- 
98-08 
1-64 
1-65 
1-88 
1-50 
•9958 
3^ 
97.12 
2-46 
2-47 
2-82 
2-25 
•9945 
4- 
96-17 
3-28 
3-30 
3-76 
3-00 
•9933 
5- 
95-23 
4-10 
4-13 
4-70 
3-76 
•9920 
6- 
94-28 
4-92 
4-96 
5-64 
4-53 
•9908 
7* 
93-34 
5-74 
5.79 
6-58 
5-27 
•9897 
8- 
92-41 
6-56 
6-63 
7-52 
6-02 
