NA TURE 



557 



THURSDAY, APRIL ii, 1901. 



OSTWALUS INORGANIC CHEMISTRY. 

 Grundlinien der anorganischen Chetnie. Von W. 

 Ostwald. Pp. xix + 795. (Leipzig : W. Engelmann, 

 1900.) 

 ■VTOTWITHSTANDING the great advances that 

 have been made during the past generation in our 

 theoretical knowledge regarding solutions and chemical 

 equilibrium in general, elementary inorganic chemistry 

 is taught to-day much in the same manner as it was in 

 the early seventies. The ordinary student at the end of 

 his junior course has a very hazy knowledge of chemical 

 facts, and scarcely a trace of chemical common-sense ; 

 but to make up for these deficiencies he knows all about 

 atoms and molecules. If he is asked how he would 

 convert, say, cadmium sulphate into cadmium chloride, 

 he will doubtfully reply, " Treat the cadmium sulphate 

 with hydrochloric acid "^this because he knows no 

 general principles concerning the facts of chemistry. 

 If, on the other hand, he is asked why hydrogen and 

 chlorine combine, he will probably answer with con- 

 fidence somewhat in these terms : " They combine on 

 account of the mutual attraction exercised by the chlorine 

 and hydrogen atoms." He does not see that he is 

 merely restating the fact in terms of an hypothesis, and 

 that the question, in our present state of knowledge, has, 

 properly speaking, no answer. The " heuristically '' 

 trained student has a better knowledge of certain facts, 

 but he is equally ignorant of general principles, and 

 equally unable to distinguish between what is fact and 

 what is theory. To him, as to the other, chemical 

 symbols, formulee, and combining weights are part and 

 parcel of the atomic theory, instead of a convenient 

 method of expressing actual facts — a method, it is true, 

 arrived at through the atomic theory, but a method 

 which would persist though the atomic theory were 

 abandoned to-morrow. 



When such a student continues his course so far as to 

 study modern theoretical and physical chemistry, he is 

 loth to part with his old ideas, which enabled him to 

 explain everything so beautifully (although in some 

 mysterious, unfortunate way they never seemed to help 

 him much when he was asked anything about facts), so 

 that example and precept, experiment and lecture, do 

 little to change his general attitude of mind towards the 

 science. 



All this is, of course, not the fault of the student, but 

 the fault of the teacher, or rather of the text-books. 

 The time that the student can devote to chemistry is, as 

 a rule, so limited that some sort of text-book is indis- 

 pensable, and this the teacher is obliged to follow more 

 or less closely if he is to avoid confusing the student. 

 Now of the elementary text-book of chemistry it may be 

 said, " plus cela change, plus c'est la meme chose ; " the 

 theory is almost invariably put before the student in 

 its ancient form long before he needs to know anything 

 about it, and long before he has a sufficient command of 

 facts and principles to understand its derivation or ap- 

 preciate its importance. The idea that a student must 

 know the atomic theory and the means by which the 



I NO. I 641, VOL. 63] 



present system of atomic weights has been arrived at, 

 beforehe istaughtthe quantitative use of chemical symbols 

 and equations, is pretty much on a par with the idea that 

 a child must know the derivation of the alphabet from 

 Egyptian hieroglyphics before he can be taught to 

 read. From practical experience of teaching on both 

 systems, the present writer can say that the student may 

 be made to use symbols and formulie very early in his 

 course without attaching to them any theoretical signi- 

 ficance whatever, and that he then uses them more care- 

 fully and correctly, because they represent to him definite 

 quantities of definite materials, and not intangible atoms 

 and molecules with which he can juggle at pleasure. 



What is wanted, then, is an elementary text-book of 

 chemistry developed from the outset in accordance with 

 "our modern theoretical knowledge. This want Prof. 

 Ostwald's book is intended to supply, and the eminence 

 of the author as investigator, writer and teacher is a 

 sufficient guarantee of interesting and instructive reading. 



So far as general arrangement is concerned, the book 

 differs in no important respects from other text-books 

 in the systematic description of the elements and their 

 .chief compounds. Physical and theoretical matters, 

 however, are made subservient to the descriptive work, 

 and are introduced as occasion requires. Thus the gas- 

 laws come under the heading of oxygen ; chemical 

 forces, molecular weight, partial pressure, mass action, 

 chemical equilibrium and catalysis, under hydrogen. 

 The phase-rule is introduced in connection with water, 

 to receive further exemplification under chlorine, 

 sulphur, &c. In the same chapter are also discussed 

 combining weights, the atomic and molecular theories 

 and the law of reaction. Thermochemical equations are 

 taken up in connection with hydrogen peroxide, photo- 

 chemical action under chlorine, and electrolysis under 

 hydrochloric acid. Valency appears halfway through the 

 book in connection with phosphorus, and the last chapter 

 of all deals with the choice of combining weights and 

 the periodic system of the elements. Atoms and mole- 

 cules are conspicuously absent. 



These examples show the plan of treatment adopted ; 

 theory is throughout properly subordinated to fact and 

 clearly distinguished from it. 



As an instance of the modern aspect presented by the 

 descriptive work in detail we may take the following 

 section, which treats of the soluble salts of bismuth. 



^'- Bismicthion. — Bismuth forms one sort of elementary 

 ion, the trivalent bismuthion Bi'". This is almost the . 

 only ion derived from bismuth, for the tendency of this 

 metal to form complex ions is extremely small, only a 

 few complex organic ions containing bismuth being 

 known. 



" Bismuthion is colourless and forms an extremely feeble 

 base with hydroxyl. The phenomenon of hydrolysis is 

 consequently so pronounced in bismuth salts that it can 

 be used as a characteristic test for them. As the basic 

 compounds formed in this way are very slightly soluble 

 in water, the bismuth salts can be precipitated by merely 

 diluting them with water : on addition of acid the pre- 

 cipitate is re-dissolved. 



" The best known bismuth salt is the nitrate, which is 

 obtained in the form of the hydrated crystals, 

 Bi(N03)3,5H20, when the solution of bismuth in nitric 

 acid is crystallised. When water is poured over these 

 crystals, a snow-white crystalline powder of basic nitrate, 



B B 



