6o 
Non- Actinic  Glassware. 
Am.  Jour.  Pharm. 
Feb.,  1877. 
that  said  notion  still  prevails,  although  physicists,  many  years  ago,  have 
proved  that  chemical  action  is  intimately  connected  with  the  blue  rays. 
The  solar  spectrum,  as  is  well  known,  consists  of  several  colors, 
ranging  from  violet  in  the  one  end  to  red  in  the  other  end  ;  by  further 
examination  it  has  been  proved  that,  while  the  greatest  heat  is  found  in 
the  red  end,  the  violet  end  possesses  the  greatest  chemical  action. 
Thus,  while  red,  yellow  or  orange  rays  give  light  enough  to  see  by,  for 
chemically  sensitive  substances  they  are  equivalent  to  darkness. 
Further,  we  know  that  when  we  pass  solar  light  through  a  colored 
glass  it  simply  intercepts  all  rays  which  are  not  of  the  color  of  the 
glass,  that  is  to  say,  we  filter  away  a  large  portion  of  the  light  with  the 
peculiar  properties  pertaining  to  it ;  consequently  we  have  to  employ  a 
color  which  strains,  as  it  were,  the  light  from  the  rays  which  we  wish 
to  exclude. 
Red  glass,  being  chemically  most  inactive,  was  first  tried,  but  being 
quite  expensive  it  was  only  employed  occasionally  ;  yellow  glass  next 
had  its  share  of  attention,  but  laboring  under  the  same  defect  (chloride 
of  silver  giving  the  purest  yellow)  it  was  discarded  and  people  returned 
to  black  and  blue  glass.  In  the  meantime  a  cheap  substitute  for  black 
glass  was  extensively  used,  viz.  :  painting  bottles  with  asphaltum 
varnish,  which  answered  perfectly,  being  black  by  reflected  light,  and 
still  sufficiently  transparent  to  enable  one  to  examine  the  contents. 
On  observing  that  the  said  varnish,  in  thin  layers  and  by  transmitted 
light,  had  an  amber-yellow  color  it  was  thought  that  dark-yellow  glass, 
which  is  quite  cheap,  might  be  used,  so  much  the  more  as  it  was  more 
elegant. 
This  dark-yellow  glass  is  produced  by  carbon  (by  adding  to  the 
melted  glass  either  refuse  organic  matter  or  finely  powdered  coke)  ; 
Splitgerber  (Dingier  cxxxviii,  292)  recommends  a  small  percentage 
(  330  per  cent.)  of  sulphur  (if  per  cent,  sulphate  of  soda  with  a  little 
sugar)  to  white  glass.  E.  Becquerel  ("  Annales  de  Chim.  et  de  Phys.," 
1843,  lx">  2^3^  etc">)  proved  that  mere  traces  of  finely  divided  particles 
completely  cut  off  the  chemical  rays. 
Messrs.  Whitall,  Tatum  &  Co.,  of  Philadelphia,  were  induced  to 
manufacture  such  glass,  and  it  can  now  be  had  at  the  same  price  as 
flint  glass  bottles. 
The  "  Danish  Pharmacopoeia,"  of  1868,  was  the  first  (and,  as  far 
as  known  to  the  writer,  still  the  only  one)  to  direct  the  use  of  either 
