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 & Tea now cited in the NHS's own guidelines on staff blogging. Unusually for a newly published mainstream book, the entire text of the book was placed online under a Creative Commons Licence. The book has also inspired the TV series "Sirens", which first aired in June 2011 on Channel 4. Blood, Sweat & Tea Blood, Sweat & Tea is a book by ambulance technician Brian Kellett, writing under the pseudonym Tom Reynolds, about life in the London Ambulance Service. The book is compiled from posts and correspondence from the blog Random Acts of Reality, one of the earliest high-readership blogs in