2 PRINCIPLES OF CHEMISTRY 



or material 2 of which all the objects of the universe are made up, with 

 the transformations of these substances into each other, and with the 

 phenomena 3 which accompany such transformations. Every chemical 



have already succeeded in becoming acquainted with certainty with much of the invi- 

 sible world, which directly is imperceptible to the organs of sense (for example, the mole- 

 cular movement of all bodies, the composition of the heavenly luminaries, the paths of 

 their movement, the necessity for the existence of substances which cannot be subjected 

 to experiment, &c.), and have verified the knowledge thus obtained, and employed it for 

 increasing the interests of human life ; and therefore it may be safely said that the induc- 

 tive method of investigation is a more perfect mode of acquiring knowledge than the 

 deductive method alone (starting from a little of the -unknown accepted as incontestable 

 to arrive at the much which is visible and observable) by which the ancients strove to 

 embrace the universe. By investigating the universe by an inductive method (endeavour- 

 ing from the much which is observable to arrive at a little which may be verified and 

 is indubitable) the new science refuses to recognise dogma as truth, but through reason, 

 by a slow and laborious method of investigation, strives for and attains to true de- 

 ductions. 



2 A substance or material is that which occupies space and has weight. That is, 

 which presents a mass which is attracted by the earth and by other masses of material, 

 and of which the objects of nature are composed, and through which the movements and 

 phenomena of nature are accomplished. It is easy to find out by examining and 

 investigating, by various methods, the objects met with in nature and in the arts, that 

 some of them are homogeneous, whilst others are composed of a mixture of several 

 homogeneous substances. This is most clearly seen in solid substances. The metals 

 used in the arts (for example, gold, iron, copper) should be distinguished for their 

 homogeneity, otherwise they are brittle and unfit for many uses. Homogeneous matter 

 exhibits similar properties in all its parts. By breaking up a homogeneous substance we 

 obtain parts which, although different in form, resemble each other in their properties. 

 Glass, the best qualities of sugar, marble, &c., are examples of homogeneous substances. 

 But examples of non-homogeneous substances ai'e much more frequent in nature and the 

 arts. Thus the majority of the rocks are not homogeneous. In porphyries bright pieces 

 of a mineral called ' orthoclase ' are often seen strewn amongst the dark mass of the rock. 

 In ordinary red granite it is easy to distinguish large pieces of orthoclase mixed with 

 dark semi-transparent quartz and flexible laminae of mica. Nor are plants and animals 

 homogeneous. Thus leaves are composed of a skin, fibre, pulp, sap, and a green colouring 

 matter. This is clearly seen by examining under a microscope a thin slice cut off a leaf. 

 As an example of those non-homogeneous substances which are produced artificially, 

 gunpowder may be cited, which is prepared by mixing together known proportions of 

 sulphur, nitre, and charcoal. Many liquids, also, are not homogeneous, as may be observed 

 by the aid of the microscope, when drops of blood are seen to consist of a colourless 

 liquid in which red corpuscules, invisible to the naked eye owing to their small size, are 

 floating about. It is these corpuscules which give blood its peculiar colour. Milk is also 

 a transparent liquid, in which microscopical drops of fat are floating, and which rise to the 

 top when milk is left at rest, forming cream. When the fat is beaten up (churned) the 

 separate drops collect into one mass. It is possible to extract from every non- 

 homogeneous substance those homogeneous substances of which it is made up. Thus 

 orthoclase may be separated from porphyry by breaking it off. So also gold is extracted 

 from gold-bearing sand by washing away the mixture of clay and sand. Chemistry deals 

 only with the homogeneous substances met with in nature, or extracted from natural or 

 artificial non-homogeneous substance. The various mixtures found in nature form the 

 subjects of other natural sciences as geognosy, botany, zoology, anatomy, &c. 



3 All those events which are accomplished by substances in time, are termed ' pheno- 

 mena.' Phenomena in themselves form the fundamental subject of the study of physics. 

 Movement is the primary and most generally understood form of phenomenon, and there- 

 fore we endeavour to reason about other phenomena as clearly as when dealing with move- 



