Blood blood clotting in a transparent container. When blood is drawn in a glass container and left undisturbed for about an hour, four different layers can be seen. A dark clot forms at the bottom (the "black bile"). Above the clot is a layer of red blood cells (the "blood"). Above this is a whitish layer of white blood cells (the "phlegm"). The top layer is clear yellow serum (the "yellow bile"). The ABO blood group system was discovered in the year 1900 by Karl Landsteiner. Jan Janský is credited with the first classification of blood into the four types (A,
Greatest Hits (Blood, Sweat & Tears album) Greatest Hits (Blood, Sweat & Tears album) Greatest Hits is a compilation album by the band Blood, Sweat & Tears, initially released in 1972. Although Blood, Sweat & Tears continued to record and tour for several more years, the band's lineup changed dramatically after "Blood, Sweat & Tears 4". This compilation album includes all of the group's best-known material up to that time. This was the group's last album to earn a Gold Record award. Columbia initially chose to incorporate the edited single versions of many of the songs, a decision which was poorly received by some fans. Some later