This section is from the book "The Steward's Handbook And Guide To Party Catering", by Jessup Whitehead. Also available from Amazon: Larousse Gastronomique.
White of egg is albumen in its purest form. It is abundant in the flesh of chickens, rabbits, fish, and is a constituent of all sorts of meat in a greater or less degree. When chicken meet or chopped beef is set over the fire in cold water, the water becomes milky while heating through the albumen flowing out of the meat When boiling heat is reached, the milky appearance is changed to perfect clearness of the water, and the albumen has risen to the surface in the form of scum. If the chicken had been dropped into boiling water, the albumen and other juices would not have flowed from the meat, but remained within it This is why a leg of mutton or other fresh joint should be set on to cook in boiling water, that the gravy may be kept in the meat until it is cut; the albumen of the outside cooks instantly and keeps in the juices. But to make soup or stews the meat should be put on in cold water. Albumen is used in immense quantities in manufactures, especially in calico printing. The demand for albumen has led almost to the extermination of the immense flocks of wild birds, such as snipe, plover, curlew, widgeon and various species of ducks which breed on the islands of the northern sea and formerly swarmed at certain seasons along our coasts, for their eggs have been gathered by the vessel load year after year, until there was no longer a harvest left to gather, unless new breeding places could be discovered.
A new source of supply of albumen has now sprung up; the blood from the large slaughter houses is contracted for by firms that makes a business of extracting the albumen from it for use in the arts, and convert the remainder of the blood into fertilizers. (See article on eggs).