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,
Blood, Sweat & Tears (Blood, Sweat & Tears album) City. The studio had just taken delivery of one of the first of the model MM-1000 16-track tape recorders, built by Ampex. The new technology allowed for far more flexibility in overdubbing and mixing than the 4 and 8-track tape recorders which were standard in 1968. The album was among the very first 16-track recordings released to the public. An additional song, "Children of the Wind" was recorded for the album but was not included. It later appeared on the compilation, "The Very Best of Blood, Sweat and Tears: What Goes Up!" The album was selected for the 2006 book