NATURE 



521 



THURSDAY, OCTOBER i, 1903. 



MRS. MARCET REDIVIVA. 



Die Schtile der Chetnie. Erste Einfuhrung in die 

 Chemie fiir ledermann. By Wilhelm Ostwald. 

 Part i., General Considerations. Pp. vii+186. 

 (Braunschweig : Friedrich Vieweg und Sohn, 1903.) 

 Price 4.80 marks. 



PROF. OSTWALD is an ingenious man ; in his 

 own language, the attribute might be expressed 

 by the adjective " schlau." Having, as he tells us in 

 his preface, published volumes of the greatest import- 

 ance, and of the widest range, on physical chemistry 

 for the use of investigators in the domains of chemistry 

 and physics, and having next written his work on 

 elementary chemistry for the ordinary student com- 

 mencing the study of the subject in universities or 

 Polytechnika (a work of which an excellent English 

 translation by Dr. Findlay has been brought out), he 

 now makes an attempt in this very elementary work 

 to reach a larger public, and has written this most 

 amusing book for the use of youngsters about ten to 

 thirteen vears of age. The plan adopted is to intro- 

 duce by means of dialogue some chemical facts con- 

 cerning hydrogen, oxygen, water, nitrogen, air, and 

 carbon and its oxides, and incidentally to consider the 

 nature of pure substances and mixtures, including 

 solutions, the phenomena relating to change of state, 

 and the behaviour of gases with alteration of pressure 

 and temperature. All these subjects are treated 

 in a philosophical manner, and his own views are in- 

 cidentally, and one might almost say insidiously, 

 introduced, so as to set the young mind on what he 

 considers to be the right track. 



Beginning with the notion of a " Stoff," or " stuff " 

 — a convenient word, inasmuch as the word " Sub- 

 stanz," or " substance," from its derivational point of 

 view, by no means accords with the views of the author 

 — ^the properties of a stuff— sugar — are considered, and 

 the pupil is made to reject the idea of a " substance " 

 by subtracting properties, and recognising that there 

 is no underlying entity. " You must rid yourself of 

 the idea," the pupil is told, ** that there is anything 

 underlying the properties of a thing, which is more 

 real or important than the properties themselves. 

 Formerly, before science had progressed, people held 

 such notions, and our language still retains expressions 

 which almost force us to accept the notions. But 

 when once that error is recognised, it can be avoided." 

 To which the pupil replies that he is afraid that he 

 will have difficulty in getting rid of the old views. 

 " But," replies the teacher, "when you know more 

 chemistry, you will see that you have to do only with 

 the properties of stuffs, and never with their real 

 nature ; so that you will forget the incorrect method of 

 expression." 



Later on, in talking about the melting point of ice, 

 the teacher defines it as " that temperature at which 

 solid and liquid can exist beside each other "; and the 

 NO. 1770, VOL. 68] 



pupil asks, "Then, who made this law?" The 

 teacher answers, " The word law is only a way of 

 speaking. It has been found that stuffs behave like 

 this, and they have been compared to obedient pupils 

 who always do what they are told. In science the 

 word law means only that we find that things are re- 

 lated to each other in a certain way; and that is ex- 

 pressed in a general form." 



In discussing change of state, the teacher refers to 

 the term "state of aggregation," and explains it by 

 the conception of atoms. He elucidates the word 

 "hypothesis," but declines to accept the atomic hypo- 

 thesis as an " explanation " of states of aggregation, 

 and suggests the word " Formarten," and this leads 

 to the consideration of differences between the states 

 of solid, liquid, and gas. Having got the pupil to 

 infer that liquids when cooled become solid, and solids 

 when heated melt at definite temperatures, the pupil 

 asks, " What determines these temperatures? " 

 " That is a stupid question. You should rather ask : 

 To what other properties do they show that they are 

 related? It is just as if you were to ask: why are 

 there camels? All that you can ask is, what are the 

 properties of these animals, and how are these proper- 

 ties connected with those of other animals? " 



Talking of the combustion of a candle and its dis- 

 appearance, the pupil says, " But it really vanishes 

 before my eyes." "Yes," says the teacher, "it be- 

 comes invisible. But can't it change into something 

 invisible? " " There are no invisible things," says the 

 pupil. " Oho! " replies the teacher. " No," says the 

 pupil, "ghosts and goblins don't exist." " Even they 

 are said to be sometimes visible," answers the teacher. 

 " But can you see the air? " " Hum — no," says the 

 pupil. " But the air is changed by burning. I don't 

 see how." And so the formation of an invisible gas 

 is brought out, and the method of determining its 

 weight. 



In considering heat and light produced by combus- 

 tion, their absence of weight is remarked, and the 

 pupil guesses that they are "forces." The teacher 

 corrects, and explains that what used to be known as 

 force is now known as energy, and that it is defined 

 as " what causes things to change." Stuffs contain 

 chemical energy when they can act on each other and 

 form new stuffs, and part of their chemical energy 

 takes the form of heat or light, and sometimes of 

 electrical or mechanical energy. The pupil is made 

 to throw out suggestions on the conversion of one 

 form of energy into another, and his own energy is 

 traced to the chemical energy he takes in as food. 

 " But I am often hungry, even when I do nothing," 

 says the pupil. And it is explained that his tempera- 

 ture has to be maintained, and that if he likes he can 

 produce light by rubbing two pieces of sugar together, 

 and electricity by rubbing sealing-wax with a cloth. 

 In this way an idea is given of transformation and 

 equivalence of energy. 



Compounds and elements are next considered, and 

 the pupil asks the natural question, " Are the con- 

 stituents actually in the compound or not? " " You 

 haven't considered your question. A compound is not 

 a bag or a box in which something can be contained. 



< . , z 



