This varies considerably even in health, and is much affected by food and medicine, and also by various morbid processes. If of a smoky or red aspect, it should lead us to suspect the admixture of blood; or, if higly colored, uric acid; a very light color usually denotes an increase of water, as in diabetes, hysteria or nervous affections; or, if green, yellow or brown, bile should be suspected, although very much the same tint is imparted to the urine if the patient has been taking rhubarb. The color is deepened if he has been drinking strong coffee; a violet color is imparted to it if he has been taking turpentine; and a yellow color from taking senna; while disintegrated blood renders it black. In health, the color usually varies from a pale straw to a brownish yellow. Highly colored urine usually indicates the existence of some pathological condition, and generally leads us to suspect organic disease of the liver, or some inflammatory disease, if not due to an excess of uric acid or urates. The presence of bile, which is indicated by a dark olive tint in the urine, may be rendered certain by a small quantity of nitric acid, for as soon as the two fluids are brought in contact, the drop of acid will be fringed with a beautiful display of colors, green, violet and red, which will rapidly disappear.