12  Inorganic  Chemicals  of  the  U.S. P.      { ATammVryPi9«[.m' 
tion  of  the  clumsy  titles  Sodium  Hydroxide,  Potassium  Hydroxide, 
Calcium  Oxide  and  Magnesium  Oxide,  for  the  simpler  and  equally- 
distinctive  terms  soda,  potassa,  lime  and  magnesia,  employed  by 
former  pharmacopoeias. 
The  use  of  the  word  "  acid  "  for  an  acid  anhydride,  such  as  arsenic 
trioxide,  is  confusing,  especially  to  students,  but  no  such  objection 
can  be  raised  against  the  use  of  the  word  "soda"  for  sodium 
hydrate,  now  that  we  are  learning  to  call  the  metal  itself  sodium. 
Imagine  a  physician  taking  the  time  to  write  out  "  Liquor  Sodii 
Hydroxidi  "  ! 
Nor  does  the  change  of  the  simple  Spiritus  Glonoini  into  the- 
cumbersome  Spiritus  Glycervlis  Nitratis  seem  very  happy. 
CHANGES  IN  FORMULAE. 
The  reduction  of  chemical  formulae  to  their  simplest  form,  such  as 
Alum  from  K2A12  (S04)4  24H20         to  KA1  (S(V2  i2H20 
Ferric  Alum  "    (NH4)2  Fe2  (S04)4  24H20  "  NHtFe(SOl)2  I2ff20 
Ferric  Hydrate  "    Fe2  (OH)6  "  Fe  (OH)3 
Ferric  Chloride  "    Fe2Cl6  "  FeCl3 
Mercurous  Chloride     "    Hg2Cl2  "  HgCl 
Mercurous  Iodide        "    Hg2I2  "  Hgl 
is  a  sacrifice  of  theory  to  simplicity,  and  in  view  of  the  present 
indefinite  knowledge  of  the  real  molecular  weights  of  these  bodies, 
the  change  is  perhaps  for  the  best. 
From  the  pedagogic  standpoint,  however,  the  new  formulae  are 
less  easy  to  explain  than  were  the  old. 
CHANGES  IN  STRENGTH. 
Changes  of  this  character  in  the  new  pharmacopoeia  have  been  in 
the  direction  of  sensible  acceptance  of  actual  conditions.  Thus  the 
absurdly  severe  requirement  of  the  U.S. P.  1890  for  Chlorinated 
Lime  (36  per  cent,  chlorine)  has  been  lessened  to  30  per  cent.  ;  while 
the  chlorine  requirement  for  Solution  of  Chlorinated  Soda  has  been 
reduced  from  2-6  per  cent,  to  2-4  per  cent.  Since  the  recipe  for  the 
manufacture  of  the  latter  has  been  improved  by  increasing  the  amount 
of  chlorinated  lime  employed,  the  process  is  much  more  feasible 
than  was  the  impossible  recipe  of  1 890. 
Sulphurous  Acid  has  been  reduced  from  6-4  per  cent,  to  6  per 
cent. ;  Solution  of  Lime  from  016  per  cent,  to  0*14  per  cent.  ;  Solu- 
