Steam

William Ripper

Description

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. A piece of cold iron can be made red hot by hammering it. A carpenter's saw, an engineer's chisel, or turning tool, soon get hot when a rubbing action, or friction, is set up between the tool and the work, although they are all quite cold to begin with. Sir Humphry Davy melted two blocks of ice by rubbing them one upon another, from which he concluded that 'the immediate cause of the phenomenon of heat is motion and this is now the generally accepted View of the nature of heat. Still we know that things may be hot without being visibly in motion hence, if heat is motion, the motion must exist in parts of the body too minute to be seen. All bodies are composed of minute particles called mole cules, held together by mutual attraction or cohesion, and these molecules are in a state of continual agitation or vibra tion. The hotter the body the more vigorous the vibrations of its constituent particles. In solid bodies the vibrations are limited in extent. If this limit is exceeded, owing to addition of heat, cohesion is sufficiently overcome to enable the particles to move about freely and without restriction, and the solid has now become a liquid. On still continuing the heat, further separation of the molecules takes place, cohesion is completely overcome, and they fly off in all directions. The liquid has now become a gas. The pressure exerted by the gas on the interior surface of the vessel in which it is confined is due to the collision of the molecules with the sides of the vessel. The greater the intensity of the heat the more violent the impact, and there fore the greater the pressure exerted. This is the condition of things in the interior of a steam boiler. If a part of the enclosing vessel were movable, it would evidently be pushed backward and outward. This is what happens to the piston of the steam engine.

Sujets

• Sciences et techniques

Informations

• Publié par: Forgotten Books
• Date de parution: 27 novembre 2019
• Nombre de lectures: 0
• EAN13: 9780243616091
• Langue: English
• Poids de l'ouvrage: 7 Mo

Extrait