Re: how comes blood comes out red but turns brownish color when it dries?

When blood is exposed to air it turns from red to brown. This is because
iron is a part of hemoglobin (which is what is inside the red blood cells)
giving blood its red color.  When the iron comes in contact with oxygen in 
the air it becomes oxidized and turns to a brown color.  This is similar to 
how metals which contain iron become rusty and change from their original 
color to a reddish-brown color.