6 



MATTER AND ITS MEASUREMENT 



it is yellow, crystalline (Fig. 3), brittle; it sinks in water, and does not 

 dissolve in water; it melts when heated, giving a clear, yellow liquid; 

 it burns readily in the air (cf. 51). Wood 

 tipped with sulphur, phosphorus, and some other 

 substances makes up another body, a match 

 (cf. 72). Now, the properties of the substances 

 Fio 3 composing a match make the iises of the match 



A Sulphur Crystal. quite different from the uses of a pencil. 



General and Special Properties. We must remember 

 that the properties of a body, such as its filling space, hav- 

 ing weight, etc., are the general properties of all matter, 

 and do not belong to one substance more than to another. 

 The special, or specific, properties of a substance belong 

 to that substance alone. No two substances have exactly 

 the same special properties. 



6. How We Measure Space and Matter. We know 

 from experience that all bodies have three dimensions; 

 namely, length, breadth, and thickness. We also think of 

 space as having these dimensions. When we say that a 

 body has a definite volume, we mean that it fills a definite 

 amount of space. We do not know what space is, but we 

 distinguish between space and matter, 

 calling that " space" which is not filled 

 with some object. On the earth, a por- 

 tion of space from which matter has 

 been removed is called a vacuum. As 

 already stated (cf. 4), air and other 

 gases are matter, not space. 



If a body is regular in shape, we can 

 readily calculate its volume. Thus, we obtain the vol- 

 ume of a cube (Fig. 4) from the formula, 



FIG. 4. 



