THIS IS NOT MEDICAL ADVICE. It’s meant as historical or amateur chemist use. I am not responsible for any misuse you make of it.
There are a substantial number of rapid color-changing combinations in your house and drug stores. Not all of them are pH-based. I’d enjoy hearing about others. Surely I wasn’t the only mad child-scientist!
IODINE was one of my favorites as a child. It was sometimes used to purify bacterially contaminated water. (Camping stores may carry liquid iodine solutions for this purpose, but the tablets are typically a mixture of iodine and potassium iodide, which greatly increases the solubility of iodine in water) Drinking a few drops of drugstore tincture of iodine won’t harm you, but it is toxic in gram quantities, so beware. Depending on the dilution, a water solution can range from almost colorless to the color of whiskey. It doesn’t taste great.
If you add STARCH to an iodine solution, it will almost instantly turn a beautiful deep midnight blue (or medium to pale blue at high dilutions) Spray starch is non-tocis, and works well, and though I have never tried it, the chemistry dictates that food cornstarch or potato starch should work as well.
SODIUM THIOSULFATE (also sold in photography stores as “hypo” for sodium hyposulfate) will cause a brown iodine-water solution to instantly turn clear (it’s also useful for eliminating the stains caused by crystalline iodine; the stain remains until the iodine sublimates <evaporates from solid to gas>, and is merely decolorized by the thiosulfate, so the stain may reappear after washing, because the iodine tends to bind organic materials more strongly than the thio. In time the iodine wile evaporate on its own) As a child, I used this effect to ‘turn whiskey into water’ (or vodka) in magic shows. It is used as an adjunct in treating cyanide poisoning, chemotherapy toxicity and other serious poisonings, but it is somewhat toxic in large doses (the standard doses are in increments of almost 1/2 oz). Personally, I never drank the solutions in my magic show
Iodine crystals (which are deep purple-black) also have many other interesting “magic show uses”. An almost invisibility thin layer painted (e.g. in letters) on a surface will stain skin brown. A crystal tossed on a very hot surface will sublimate in a poof of bright violet ‘smoke’ (which I wouldn’t inhale
HOMEMADE OR OVER-THE-COUNTER PH INDICATORS
You can edibly adjust pH with kitchen bases like baking soda, and kitchen acids like cream of tartar, lemon juice, vinegar, lactic acid from olives, etc. You can also change the pH of markedly acidic or alkaline solutions by diluting them with ordinary water or alcohol.
The juice produced by boiling a RED CABBAGE has many colors from a deep maroon to medium blue, over a wide pH range.
RED BEET juice will change from red to yellow, but mostly in a very alkaline pH (11-12) that isn’t suitable for drinks
METHYLENE BLUE (aka urolene blue or aniline violet [not aniline blue]) is used as a tissue stain, so don’t get any on you, but is also used internally in methemoglobinemia, a condition with many causes such as carbon monoxide poisoning of blood conditions. It can cause green to blue urine or feces. In large doses, it can cause agitation, fatigue, stomach upset and worse; in small doses, it typically causes an increased need to urinate or defecate [in blue], if it has any perceptible effect at all. They used to sell it over the counter, especially in ethnic neighborhoods, partly because it was felt to help with sickle cell attacks, and partly because it had a modest antibiotic effect, but I don’t know if they carry it anymore. I don’t imagine that there is much call for it. It’s still used in hospitals and by prescription
PHENOLPHTHALEIN (mentioned earlier, but included here for the correct spelling) is a famous laxative and acid-base indicator. It can be found in many laxatives. The plain generic tablets are easier to experiment with than (e.g.) the chocolate-based Ex-Lax.
SILVER NITRATE can be toxic and irritating to the skin and stomach, so I wouldn’t drink it much, even though it was routinely dripped directly into the eyes of newborns for generations (to prevent the possibility of syphillis infection from a mother to child during the passage down the birth canal birth) and was used as a general antibiotic for well over 100 years. It probably won’t kill you, but remember, mercury salts, arsenic and strychnine were also standard treaments against syphillis for a long time - and they are definitely dangerous! You don’t want to drink it for another reason too: any organic matierial it touches may turn black - tongue, fingers, etc. The reaction is actually a release of microfine particles of silver -the exact same principle used in black and white films- but the stain is pretty permanent, because there is no way to effectively remove the silver once it’s precipitate out. There are ways to fade it, but generally you have to wait for the surface cells to wear away.
DON’T put this in a drink. I only mention it because it can be used to do many Mr. Wizard style tricks. As ith iodine, a transparently thin layer painted on glass or metal will harmlessly stain anyone who touches it (now you can find out who’s getting into your liquor cabinet!)
ALL THE ABOVE IS MEANT FOR ‘CHEMICAL MAGIC’ SHOWS, NOT FOR HUMAN CONSUMPTION. THEY MAY BE HAZARDOUS TO YOUR HEALTH - IF ONLY BECAUSE YOUR FRIENDS WILL RIP YOU LIMB FROM LIMB. Use beakers for experiments, not people!
