368     Eighth  Decennial  Revision  of  Pharmacopoeia.  |A  August",  mo5.rm" 
The  same  is  true  of  the  pharmacopoeias  that  have  recently  been  pub- 
lished or  are  being  prepared  in  Europe. 
How  much  more  closely  the  molecular  weights  of  official  sub- 
stances, if  based  on  an  atomic  weight  of  O  =  16,  would  correspond  to 
the  molecular  weights  of  the  same  substances  as  given  in  the  phar- 
macopoeias of  1880  and  of  1890,  is  well  shown  by  the  appended 
table : 
U.S.P.  1880. 
1890. 
1900. 
G.  P.  1900 
H  =  1  +  0  =  16. 
H  =  1. 
H  =  t. 
O  =  16. 
Water  
.   .  18 
17-96 
17-88 
I8-02 
•  •  342 
341-2 
339'6 
342*22 
Morphine  sulphate  . 
•  -  758 
756-38 
752-83 
758-54 
Quinine  sulphate   .  . 
•  -  872 
870*22 
866-15 
872-78 
Strychnine  sulphate  . 
■  -  856 
854"24 
850  21 
856.78 
.   .  286 
285-33 
283-99 
286-18 
.  .  1697 
169-55 
168-69 
169-97 
Sodium  phosphate  . 
•  -  358 
357*32 
355-6i 
358-35 
286-9 
286-64 
285-41 
2876 
Specific  Gravity  and  Solubility. — The  adoption  of  25 0  C.  {JJ°  F.) 
as  the  standard  temperature  at  which  the  specific  gravity  as  well  as 
the  solubility  of  the  several  chemical  substances  are  to  be  determined 
and  compared  will  undoubtedly  meet  with  general  approval,  and  is 
quite  in  keeping  with  a  number  of  other  practical  advances  that  have 
been  made  in  the  chemistry  of  the  new  U.S.P. 
This  degree  of  temperature  is  so  nearly  the  average  of  that  main- 
tained in  habitations  in  temperate  climates,  that  there  should  be  lit- 
tle or  no  difficulty  to  obtain  and  maintain  it,  even  with  the  limited 
amount  of  apparatus  usually  found  in  the  average  pharmacy.  The 
adoption  and  use  of  this  readily  obtained  degree  of  temperature 
should  do  much  towards  inducing  pharmacists  to  apply  many  of  the 
prescribed  tests  for  the  different  official  drugs  and  preparations,  and 
thus  make  them  familiar  with  the  importance  of  specific  gravity  and 
solubility  as  an  indication  of  the  identity,  purity  and  strength  of 
many  of  the  official  substances. 
Appendix. — This  portion  of  the  book  can  hardly  be  said  to  have 
been  subjected  to  any  radical  changes,  the  bulk  of  the  contained 
material  and  the  manner  of  arranging  the  same  being  practically  the 
same  as  that  of  the  Pharmacopoeia  for  1890.  A  special  table  of 
contents  has  been  added,  and  the  whole  section  appears  to  have 
been  carefully  revised  so  as  to  bring  it  fully  in  harmony  with  the  ad- 
