What caused the change in color of litmus paper?
154941
when acid or alkiali is poured on it
669120
may be bleaching is the answer
785815
Its an historic hang on to the times when output was to line printers.\n\nLine printers printed on a continuous strip of paper that had perforations after every page. Form feed caused them to feed to the next perforation - ie the top of the next page or form.
973408
Talk about how paper is made.
818456
paper is pulpified wood that's dried into thin sheets.  Any liquids (grease, water, etc) will soak into the mix and separate the fibers, causing it to become transparent.  Except with water, it will ultimately evaporate out.  Grease doesn't evaporate away at room temperature like water does, so the transparency remains.
998973
This site is a paper that was written on the colors. Just use it as a guide, some of the ideas are stretching it a bit though.
1042216
It seems there's a variety of things that can cause this.  If you go the link below, you'll see a number of different things people did to resolve this issue, especially on page 2.
612303
Don't know, but the brown colour of excrement is caused by a compound called bilirubin (not sure of the spelling) and this is a hydrogenated porphyrin. Porphyrinato compounds can lose energy by oxidising and the part in contact with the air could do this more rapidly and hence change colour. Not sure though.
1116232
There are many types of pH indicators which will change color withint a certain range of pH values.  Many of these indicators might be dificult for the "common person" to get a hold of though.\n\nUsing Litmus paper is an easy way to test the pH of a substance.\nBased on the color change of the Litmus paper, a general idea of the pH can be determined.\n\nOne can also use other, natural, indicators.\nFor example, red cabbage contains a natural pH indicator which can be extracted by boiling (this will STINK up your whole house, best to do it outside of possible).\nhttp://chemistry.about.com/library/weekly/aa012803a.htm\n\nYou can also get pH probles whcih work by placing an electrode into the solution to be measured and getting a reading off of the either digital display or, in the case of cheaper probles, the value the needle points to on the meter.  Some of the "good qualitity" probles can be a little expensive, but a cheap substitute is a soil pH meter.  Although soil pH metes are really not designed to be used to measure a solution's pH and only have a limited range, it can work well for many applications.\n\nIf you want to get a numeric value for the pH,\nMy advice is to go with the soil pH meter if you dont plan on measuring anything which will have pH values below roughly 3 or 4 and nothing higher than about 8 or 9.  If you do plan to, you might want to go with a "real" pH meter.\n\nIf you just want a general range of the pH (whether something is just acidic or alkiline), then go with Litmus paper or some other form of cheap indicator (cabbage juice).
208500
Perhaps the plants transpiration processes of; photosynthesis, CO2, & nitrogen along with other conditions, ie. H2O temp., Ph level, UV length of intensity play a part of the chemical transformation of plant material to become reddish in color.  Ideally, a micro nutrient of Fe (iron) would make a difference but not certain.
647043
(NH4)SO4 is ammonium sulphate and is a base and will turn litmus paper blue and phenolphthalein pinkish\nH2CO3 is Hydrogen carbonate and will produce no change in either as it is a neutral compound in both.
840358
When you first add the bromothymol blue to your acidic solution, it will give a bright yellow color to the solution.\nWhen you titrate with NaOH, the endpoint will be a color change to Blue.
1118094
http://www.peacehealth.org/kbase/topic/detail/drug/hw155236/detail.htm  Certain medication can cause color change, usually darkening them.
25146
The heat from the parts that are burning alters the chemical composition of the paper coating on one side, "shrinking" that side and causing the paper to curl.
560891
paper made from straw
193833
if the paper is use white out
571970
Acid +Alkali =Salt + Water\nHence,\n\nNaOH + HCl = NaCl + H2O\n\nWhen litmus paper is dipped in NaOH solution it turns blue it means that NaOH is basic in nature.When HCl is added to NaOH The mixture becomes acidic and so the litmus paper turns red.The product you get after mixing both solutions is common salt and water so when this is heated the water evaporates and the salt is left back.This is a small experiment which you can do by adding salt to water and then heating it till the water gets completely evaporated.