ABSTRACT
The term general fluid is applied to any substance that offers little or no resistance to change of shape to an applied force. Divided into three classes: liquids, vapours, and gases, it is liquids that offer the greatest resistance to compression and are not greatly affected by changes in temperature, whereas vapours and gases are easily compressed and are more susceptible to temperature changes. Solids may be made to behave as fluids in which they are dispersed as particles in liquids, vapours, or gases as in pneumatic conveying, which is a method of transporting solid particles such as grain and involves mixing the particles in a strong current of air. Toothpaste, pâte, and paints are fluids in which they retain their shape until an external force is applied causing them to flow, such as by way of a knife or brush.
