March 9, 1905] 



NA TURE 



435 



the cerebral organisation are specially well done, and 

 contain the best exposition yet published of our know- 

 ledge of that part of the Primate organisation. 

 Special prominence is deservedly given to the 

 brilliant work of Prof. Elliot Smith. There can be 

 no doubt, too, that this work will lead to a renewed 

 vigour in the search for evidence bearing on the 

 origin and relationships of the higher Primates. 



.\. K. 



CHEMISTRY FOR YOUTHS: MRS. MARCET 

 REDEVIVA. 

 Die Scliide dcr Chcmie. By W. Ostwald. Zweiter 

 Teil — Die Chemie der Wichtigsten Elemente und 

 Verbindungen. Pp. viii + 292. (Brunswick : 



Vieweg and Son.) Price 7-20 marks. 



ABOUT a year ago, the first volume of Prof. Ost- 

 wald 's dialogues on chemistry was noticed in 

 these columns. We have now' the second volume, 

 written in as lively a strain as the first, and conveying 

 the author's views, which bid fair to become in the 

 main everybodv else's views, as regards the presentation 

 of the elementary facts of chemistry. It would be wrong 

 to say that in this volume, consisting of 292 pages, 

 there is more system ; but in it we come to a dis- 

 cussion of chemical facts and theories which are 

 generally treated in school text-books. The pupil is 

 introduced to chlorine, its preparation and properties ; 

 its behaviour with water; acids and bases, and 

 elements; combining weights, and multiple propor- 

 tions ; the atomic hypothesis, and the laws of volume 

 combination ; electrolysis and salts. Chlorine is 

 again considered as regards its compounds with 

 oxygen, and then follow bromine and iodine; sulphur 

 and its compounds; nitrogen, ammonia, phosphorus, 

 and so on through the commoner elements and their 

 compounds. 



Throughout the volume we find neat remarks which 

 sustain interest, at least, when it is glanced through, 

 for I do not think that anyone who is already a 

 chemist will read the volume as carefully as he 

 may have read the first volume. For example, on 

 the first page is an aphorism, too often neglected, 

 but none the less true : — " When much has been 

 learnt, time must be given for digestion." In 

 English " cramming doesn't pay in the long run." 



Everyone knows that Prof. Ostwald does not hold 

 by the atomic theory. Yet he does not escape from 

 it. His presentation of it is, however, ingenious, as 

 indeed are all his methods. Discussing the facts of 

 multiple proportion he gives the following illustra- 

 tion : — 



" Think of a collection of coins, where German 

 marks, English shillings, French francs, Russian 

 roubles, and other coins are to be found. You can 

 combine these coins in twos and threes ; each com- 

 bination, however, has the value of the sum of the 

 individual value of the coins, and you cannot obtain 

 any other values, combine them as you will. 

 Similarly, no other compounds can be formed but those 

 obtained by bringing the elements together according 

 to their combining weights." 



NO. 1845, '^OL. 71] 



The pupil then draws the required conclusion : — 

 " That is as if each element consisted only of equal 

 pieces, just as all francs or marks are equal among 

 themselves." "Yes," answers the teacher; "that is 

 the picture which has represented the state of affairs 

 to men's minds for long. It is supposed that each 

 element consists of minute particles, named atoms," 

 and so on. When the boy asks, " Is all this true? " 

 the teacher replies, " No one has seen an atom, nor 

 weighed one. This is therefore a hypothesis, but a 

 very convenient one, because the various applications 

 of the laws of combining proportions can be better 

 realised (merken) when the picture of atoms is simple 

 and clear." " But we can do without it! " says the 

 pupil. " Certainly," says the teacher. " But just as 

 you found it easier to count on your fingers than in 

 your head, so it is easier to think of atoms, than of 

 the abstract and general laws of combination." So 

 we have to teach by means of atoms. Indeed, few 

 of us would go further, especially in these later days, 

 when even atoms are failing us. The hypothesis is, 

 however, ignored a little later, when it is stated that 

 " the rule has been made never to write fractional 

 parts of combining weights." The doctrine of the 

 indivisibility of atoms would appeal more readily to a 

 young mind. Yet in fairness, it must be 

 acknowledged that the writer makes the pupil suggest 

 that each chemical symbol stands for an atom, and 

 acknowledges, in the mouth of the teacher, that " the 

 atomic theory can be easily grasped " (" etwas sehr 

 eingangliches hat •'). 



When electrolysis is discussed, the author's 

 ingenuity in devising analogies is at its best. The 

 pupil has difficulty in picturing a positive and a 

 negative current going in opposite directions through 

 the same wire. He is reminded of waves crossing 

 each other in a pond, and of the upper and under parts 

 of a driving-belt travelling in opposite directions. 



Heats of combustion, discussed under the heading 

 " carbon," are measured in kilojoules, instead of 

 calories. This is perhaps logical, but it appears to 

 the reviewer that the older unit might have been 

 retained until a later stage. It is easy to make the 

 reduction when required ; and it is easier to realise 

 heat as heat than as work, at first, at least. 



While acknowledging that the subject of chemistry 

 is here well treated, and that the author has main- 

 tained his lively style and faculty of lucid present- 

 ment, it may be questioned whether this method of 

 discussing chemistry should have precedence over the 

 ordinary text-book. A youth who advances so far as 

 to grasp the contents of volume I., will, I think, tire 

 of the plan of question and answer. Yet perhaps 

 there are some who prefer to take their food, as they 

 do medicine, in spoonfuls, and to whom the form 

 of dialogue has its attractions. In old days " Pleasant 

 Pages " was widely read, and no doubt conveyed 

 valuable lessons. And at any rate, teachers of 

 chemistry may learn much from this volume in hints 

 as to hovi- best to present the very numerous facts 

 of the science to their students, whose digestive 

 powers are as a rule limited. W. R. 



