Because the albumen becomes hard, like the white of a hard-boiled egg.
The best way of boiling meat to make it tender is this: Put your joint in very brisk boiling water; after a few minutes add a little cold water. The boiling water will fix the albumen, which will prevent the water from soaking into the meat, keep all its juices in, and prevent the muscular fiber from contracting. The addition of cold water will secure the cooking of the inside of the meat, as well as of the surface.
Why is meat always tough if it be put into the boiler before the water boils?
Because the water is not hot enough to coagulate the albumen between the muscular fibers of the meat, which therefore runs into the water, and rises to the surface as scum.
Why is the flesh of old animals tough?
Because it contains very little albumen, and much muscular fiber.
What is a poison?
A poison is any agent capable of producing a dangerous effect upon anything endowed with life.
In cases of poisoning by substances taken into the stomach, what course should be pursued, in the absence of medical attendance?
The first step is to evacuate the stomach by means of powerful emetics, and when vomiting has taken place, warm water and the white of eggs may almost always be given with advantage.