silverchloridestill covered those areas when you removed the objects.Without
"fixing"though,the light will soon affectthatsilverchloride,too. The white
images willthenbecomedarklike the restofthe cards. Keep them in adark
place or enclosed in ablackenvelope.
Makesomemorelight-sensitivepaperfor theexperimenton page 83.Don't
makeany images on thisbatch,though.Justsoaksome indexcardsin asodium
chloridesolution,thenin a silvernitratesolution,let them dry in adarkplace,
andstorethemin ablackenvelope.
HOWTO MAKE YOUR OWN PHOTOGRAPHICPLATES
Gather thesematerials:Eight or 10 small piecesofglass,measuring3"x5"or
4"x4"; I packageofunflavoredgelatin; silverbromide(AgBr);an alcohol
burner;a smallpot;a red lightbulb;blackconstructionpaper;paperclips;
a detergent;papertowels;aluminumfoil;bookends;an eyedropper;a cup;
anda glass rod.Forpartofthisexperiment,you will need the samedarkroom
youused for theprecedingexperiment.(Getyourmother'spermissionto use the
stove.)
Follow this procedure:Wash the piecesofglass with adetergent,andallow
them to dry bystandingthem on edge on thepapertowels.Youwill have to
leanthemlightlyagainstthebookends. Fromthispointon,don'ttouchthe
glass surfaces withyourfingers.Fingerprintsare oily and will spoil thephoto-
graphicplates. Dissolvet ofthe packageofgelatinintcup ofwater. PutI
cupofwaterintothepotand bring it to a boil on the stove.Addthe dissolved
gelatinandcontinueto boil for Iminute.Replacethebulbin theareayou are