Why does the skin turns yellow when nitric acid is spilled on our skin?
108119
Concentrated nitric acid dyes human skin yellow on contact, due to interactions with the skin protein keratin. Strangely, these yellow stains turn orange when alkalised.\n This test is referred to as Xantho proteic test and used to detect the presence of proteins
130267
We can be, it just doesn't show up as well on our skin.  I have very dry skin on my knees.  When you look close it appears ashy, but from afar, it doesn't.  The dead skin just blends in with my pastey white legs!
637701
Cleans off the dead skin cells, so skin looks brighter.  Also, if your skin is a bit dry, it makes it more responsive to moisturizers.  The rubbing motion also helps blood circulate.
73249
When you exercise, your body heats up.  Your body needs to release that heat somehow; hence, we sweat and we turn red.  Redness occurs when the blood vessels in the skin dilate (expand, get bigger) and move closer to the surface.  This allows the heat to dissipate because of the increased surface area.  If your skin is particularly pale, the effect is more noticeable.
76676
The skin on your elbows and knees is a slightly different texture than the rest of your skin because it's basically built to handle more abuse than the rest of your body.  Halving a lemon and "soaking" your joints in the juice does improve the coloration.  For a quick fix, peroxide also bleaches your skin.  The lemon is healthier, however.
95516
A pigment is a chemical generally containing chromium or other metals like iron,copper etc. Skin color is caused by MELANIN.Melanin is prepared in the body with amino acids like Tyrosine.
443855
more than likely it is a fungus.  I had white spots start at the back of my neck and spread out.  Upon goin to the doctor, it was discovered that there was a fungus growing on my skin and blocking UV rays of the sun, therefore, causing the skin underneath the fungus to appear to stay white.  After that, I applied an "salve" I suppose killed the fungus, and it never happened again.  I was 16 or 17 at the time.\nNow if your dark skinned by nature, I really have no idea if this is the same thing.  I myself am a pale skinned person.
1030123
in the beginning there is a lot of blood under the skin, so the color is darker, as time passes and the blood disolves, the color becomes lighter. the color is actually caused by the chemicals: \nhemoglobin and its breakdown products, bilirubin and biliverdin.
432601
the UV waves cause heterolytic fission of chemical bonds creating "radicals" which are very reactive species.  They will react with pretty much anything.  The UV radiation is therefore breaking down the skin and the colour molecules in paint and clothes, making them look like they are losing their colour.  The purpose of sun-tan lotion is not only to stop the UV radiation getting to your skin, but also to mop up all the free-radicals formed before they do any damage.  Skin cancer is caused by this process.  You are essentially changing the structure of the skin.
837944
no sunlight and the fluid that you would normally have sweated off is trapped therefore making your skin soggy - also this extra fluid will make you look paler too.
952990
Its all the diffrent types of lotions and creams that are causing the diffrent shades.\nAvoid the acids...... U will just get burnt my dear!\nLook at my Idol Michael Jackson! \nMy advice, dont even try any more of that. \nGo to a doctor for a proper prescription.\n\nGood luck
637537
It's actually a bluish-green.  Look at your veins that come to the surface of your skin.  Blood only turns red when it comes into contact with oxygen.
524766
i'm guessing, its dried soap.. or your skin is really dry..
3658
I know friends that get tan or sunburn when they go skiing on a sunny day.... perhaps you are looking for a more complex answer.
403637
There is a medical condition where the skin will "weep" albumin (a protein in the blood that helps make it liquid)
422607
When the bilirubin level gets high enough, the yellow color shows up in most visible areas--skin, urine, mucus membranes, etc; it's not just the sclera that turns yellow.
365758
Actually it is bilirubin that leads to the yellow/green discoloration in the skin and eyes. \n\nBilirubin is a breakdown product of blood and is metabolized through the liver. When the liver is not functioning well, as in the case of hepatitis, the bilirubin accumulates. Bilirubin is a pigment which then causes the discoloration called jaundice when in manifests in the skin and icterus when you see it in the eyes.\n\nDepending on the severity of the hepatitis and the etiology of the hepatitis your skin may or may not be jaundiced. If the metabolic mechanisms of the liver become overwhelmed or is not functioning adequately then the bilirubin will accumulate. After reaching certain levels, bilirubin will make the skin appear yellow.\n\nThis is also the same stuff that you may see in your vomit - it will be the greenish bitter stuff (assuming it wasn't bitter green jello you just ate or something).