730  Scientific  and  Technical  Abstracts  {Am'Jc0turi92iarin' 
the  case  of  the  fresh  oil.  The  melting  point  of  the  fatty  acids  was 
39.5 °  C,  and  the  solidifying-point  38.6°-36.5°  C.  by  the  capillary 
method. — K.  Gander  and  J.  Zellner  (Seife,  1921,  6,  411,  through 
Journ.  Soc.  Chem.  hid.,  July  30,  1921,  518A). 
Manufacture  of  Luminous  Paints. — Four  methods  for  the 
manufacture  of  phosphorescent  pigments  are  described.  The  first 
utilizes  oyster  shells  as  the  raw  material.  The  shells  are  first  washed 
with  hot  water  and  then  dried  and  calcined  at  a  bright  red  heat.  After 
cooling,  the  mass  is  crushed  and  freed  from  the  debris  of  the  exter- 
nal layers,  which  is  valueless  for  the  purpose  in  hand.  The  shell 
powder  is  then  mixed  with  a  small  amount  of  powdered  wood  char- 
coal and  transferred  to  a  crucible  made  of  a  refractory  earth,  where 
it  is  arranged  in  alternate  layers  with  powdered  sulphur.  The  cruci- 
ble, covered  by  a  lid  securely  luted  on,  is  strongly  heated  for  about 
an  hour,  and  after  complete  cooling  the  mass  is  extracted  and  pul- 
verized once  again.  A  phosphorescent  color  prepared  in  this  way 
from  an  impure  carbonate  of  lime  possesses  a  more  intense  lustre 
than  the  colors  made  from  pure  carbonate  of  lime.  In  the  second 
method  the  sulphates  of  calcium,  barium,  or  strontium  are  used  as 
the  raw  materials.  These  are  intimately  mixed  with  powdered  wood 
charcoal,  in  the  proportions  of  1  part  of  carbon  to  5  or  6  parts  of 
sulphate.  The  mixture  is  then  calcined  as  in  the  previous  process. 
In  the  third  method,  when  working  with  carbonates  such  as  marble, 
witherite,  or  carbonate  of  strontium  it  is  necessary  to  add,  in  addi- 
tion to  the  wood  charcoal,  rather  more  than  one  chemical  equivalent 
of  sulphur,  and  then  to  proceed  in  the  same  manner  as  with  the  oys- 
ter shells.  The  second  and  third  processes  give  masses  with  an 
orange,  green,  blue  or  red  phosphorescence.  The  sulphur  is  some- 
times replaced  by  antimony  sulphide  or  other  similar  sulphur  com- 
pounds. More  luminous  but  more  expensive  colors  can  be  produced 
by  starting  with  calcium  oxide,  barium  carbonate,  or  carbonate  or 
sulphate  of  strontium,  either  alone  or  mixed  with  calcium  oxide  or 
marble.  The  necessary  carbon  is  obtained  from  starch,  which  is 
mixed  with  the  above  substances.  The  carbonates  of  rubidium  and 
lithium,  as  well  as  bismuth  nitrate,  are  equally  of  service.  Some- 
times sodium  sulphate,  or  even  lead  acetate,  is  added,  and  the  formu- 
lae for  the  mixings  vary  with  each  individual  factory.    It  may  be 
