1 If you add music and files to your iPod while you are charging the battery, it will take longer for it to charge. 2  Before using your iPod nano for the first time, it is important that you let it charge for a minimum of three hours. 3  If you do not, you can weaken the battery, giving it a shorter lifespan.
Too much iron will usually turn the blood black. However, if there is liver failure, and it's seeping into the blood stream that too can cause the blood to turn black as it becomes over loaded with toxins. Put simply it's the blood is overloaded with toxins and other nutrients that the body can't process entirely.
Each hemoglobin protein is made up subunits called hemes, which are what give blood its red color. More specifically, the hemes can bind iron molecules, and these iron molecules bind oxygen. The blood cells are red because of the interaction between iron and oxygen. When the iron is oxygenated(Fe+3), it becomes red. When the iron is deoxygenated(Fe+2), it becomes blue. This is why your veins are blue. When hemoglobin is carrying a lot of oxygen (like when just leaving the lungs), blood is bright red.