236       CONTRIBUTIONS  TO  THE  HISTORY  OF  NAPTHALINB. 
phuric  acid  to  the  strychnia  than  what  is  necessary  to  dissolve 
it ;  and,  in  like  manner,  the  powdered  bichromate  of  potassa, 
or  ferricyanuret  of  potassium,  should  only  be  moistened,  as  by 
touching  a  glass  rod  with  the  point  of  the  tongue  and  then  rub- 
bing it  over  the  powder.  In  this  manner,  two  saturated  solutions 
or  mixtures  are  obtained,  which  show  the  play  of  colors  as  soon 
as  their  margins  are  brought  into  contact,  even  though  the 
quantity  of  alkaloid  present  be  very  minute. — Amer.  Journ. 
Med.  Sal,  April,  1862. 
CONTRIBUTIONS  TO  THE  HISTORY  OF  NAPHTHALINE, 
By  M.  J.  Persoz. 
After  reading  M.  Roussin's  interesting  communication,*  on 
an  artificial  colored  product,  said  to  be  identical  with  alizarine, 
I  think  I  ought  to  make  known  to  the  Academy  the  results  I 
obtained  two  years  ago,  while  studying,  with  M.  Martel,  the 
derivatives  of  naphthaline. 
Starting  from  the  fact,  established  by  us,  that  a  mixture  of 
commercial  nitre  and  sulphuric  acids,  even  in  very  variable  pro- 
portions, will,  when  heated  with  naphthaline,  readily  yield  co- 
lored products,  we  have  naturally  been  led  to  examine  the 
action  of  concentrated  sulphuric  acid  on  the  various  nitrogen- 
ized  compounds  of  naphthaline. 
This  is  a  very  difficult  study,  however  simple  it  may  at  first 
sight  appear,  because  the  least  changes  of  the  condition  under 
which  the  experiment  is  performed,  exercise  a  sensible  influence 
on  the  results.  The  dye  principle  formed,  possesses  the  prop- 
erty of  madder  in  dyeing  mordants  ;  its  color  varies  from  red 
to  blue,  and  passes  through  all  the  shades  of  violet. 
The  blue  was  only  obtained  accidentally  ;  and  we  are  unable 
to  state  the  precise  conditions  of  its  formation,  though  it  appears 
to  be  due  to  a  molecular  change  in  the  nitrogenized  naphthaline 
compound,  under  the  influence  of  a  physical  agent. 
As  the  violet-blue  tints  are  the  most  beautiful,  we  have  de- 
voted most  of  our  attention  to  them,  and  have  endeavored  to 
produce  them ;  thus  working  in  an  opposite  direction  to  that  of 
*  See  page  558,  vol.  ix.,  3d  series  Am.  Jour.  Pharm. 
