422 GLOSSARY 



Mer'cu ry, a silver- white liquid metal. It freezes at 39.5 C. and 

 boils at 357 C. Mercury ore (cinnabar) is mined in Spain, Austria, 

 Italy, and in California and Texas. It is separated from the ore by 

 roasting in closed ovens and then condensing the vaporized mercury. 

 It is also known as quicksilver. 



Mil'let, a grain grown in Europe and Asia for food for both animals 

 and man. Millet is also a general name for a number of small grains. 

 The variety grown in the United States is usually cut green and fed 

 as hay. 



Mo'ment of a force is the tendency of that force to produce motion about 

 a point or axis. It is the product of the force times the perpendic- 

 ular distance from the point to the line of direction of the force. If 

 a horse is pulling with a force of 400 pounds on a windlass lever 10 

 feet long, the moment is 4000. 



Neutral substances, those which do not have characteristics like acids 

 or bases. Common salt and pure water are examples. 



Nu'tri ents, the three divisions made of nutritious foods, namely, carbo- 

 hydrates, fats, and protein. 



Nu'tri ment, a food which promotes growth and repairs the natural 

 waste of animals and plants. Some nutriments contain all three 

 nutrients. 



Ores are compounds taken from the earth and contain one or more 

 valuable metals, such as iron, copper, mercury, silver, gold, etc. 



Or'gan ism, a living body, as a plant or animal. It may be made up of 

 organs, tissues, and cells. A one-celled animal or plant is an organ- 

 ism. 



Phe nol phthal'e in (fe nol thal'e in), a very complex substance that 

 cannot be made in the ordinary laboratory. If purchased in dry 

 form, dissolve one gram in 100 c.c. of 96 per cent alcohol. Dilute 

 bases turn colorless phenolphthalein to a red color and acids change 

 it back to colorless condition. As a test for acids and bases it is much 

 more delicate than litmus. 



Phos'phor us, a simple chemical element which oxidizes very readily. 

 Yellow phosphorus (a phosphorus oxide) must be kept under water 

 and not handled with bare fingers in the open air. Cut it under 

 water. Red phosphorus (a phosphorus oxide) is not so dangerous, 

 and ignites at 260 C. Phosphorus is used in the manufacture of 

 matches, and for fertilizer in the form of phosphoric acid. 



Piston, the sliding piece in the cylinder of an engine or pump. The rod 

 attached to it is the piston rod. In an engine the piston is moved by 

 steam or other gas; in a pump it is moved by the force applied to the 

 handle of the pump. 



Platinum electrode, a piece of sheet platinum in an apparatus for 

 decomposing water. The electricity passes into the water by one 

 electrode and leaves the water by the other electrode. 



Pneu mafic trough (nu mat'ik), an open-topped vessel with a shelf 

 in it for supporting inverted bottles full of water in such a way that a 

 tube may be inserted for catching a gas. (See illustration on page 48.) 



