166 



SCIENCE. 



[N. S. Vol. II. No. 32. 



Leipzig. 1895. Svo. Pp. 103. Price, 



2 marks. 



Under the above title Professor Arendt 

 has reprinted the introductorj- chapters of 

 his book, called ' Technik der Experimental 

 Chemie,' and in these he points out the 

 great advantages that are to be gained by a 

 study of the natural sciences in the second- 

 ary schools. In order that the pupils of 

 these schools may gain the greatest possible 

 benefit from such study he recommends 

 that they be taught physics and chemistry, 

 and that the instruction in the purely de- 

 scriptive sciences, such as botanj^ and phys- 

 iology, be omitted. In the lower classes 

 he insists that the treatment of these sci- 

 ences must be purely empirical. Facts 

 must be collected and arranged systemati- 

 cally. All speculative discussion in regard to 

 things that lie beyond what can be observed, 

 and all hypotheses of a metaphysical kind, 

 must be avoided. The minds of the pupils 

 must first be furnished with a sufficiently 

 broad knowledge of the facts of observa- 

 tion before the attempt is made to make a 

 more profound study of physical and chemi- 

 cal phenomena. It is only in the higher 

 classes that subjects of a theoretical nature 

 are to be considered, and then great care 

 must be taken by the teacher to present 

 these subjects in their true light, so that 

 the students may clearly apprehend what is 

 fact and what is hypothesis. 



The author considers first how concep- 

 tions and ideas are formed in studying 

 changes in material things, then how the 

 results of observation and experiment are 

 to be arranged and classified and how gen- 

 eralizations are to be reached. The induc- 

 tive method of working is explained in 

 great detail, and the author calls attention 

 to the unusi;ally good opportunity which 

 the study of chemistry offers for making 

 students thoroughly familiar with this 

 method of investigating nature. 



The last chapter deals with the practical 



details of instruction, what to teach and 

 how to teach it. He recommends what he 

 calls the synthetic method. The course 

 begins with a consideration of the more 

 important metals. The characteristic prop- 

 erties of these are discussed; then the chan- 

 ges that thej' undergo when they are heated 

 in the air are examined experimentally. The 

 causes of these changes are found to be due 

 to the action of one constituent of the air. 

 By further experiments the student is led 

 to discover oxygen, to determine the com- 

 position of air and water. The action of 

 oxygen upon combustibles is then taken up, 

 and this leads to the determination of the 

 nature of combustion. After the student has 

 in this way leai'ned something about the 

 class of bodies called oxides he starts again 

 with the metals and studies the effect of 

 chlorine and sulphur upon them. Thus a 

 knowledge of chlorides and sulphides is 

 obtained. A comparative study is then 

 made of the oxides, sulphides and chlorides, 

 and the methods of transforming the mem- 

 bers of one class into those of the other 

 classes are considered. The course of in- 

 struction is continued in this way until the 

 student has learned something about all of 

 the more important elements and com- 

 pounds. Throughout the entire course the 

 inductive method is used, the student be- 

 ing constantly called upon to draw his own 

 conclusions from the experiments and then 

 to test these conclusions bj^ means of new 

 experiments. 



Admirable as this plan seems to be for 

 the instruction of young students, where the 

 course can be extended through a series of 

 years, it can hardlj^ be regarded as a satis- 

 factory one for more advanced students. 

 It is onljr the simpler laM^s that can be 

 worked out inductively bj^ the students. 

 The gi-eater number have to be imparted to 

 them directly, and the explanation given of 

 how these laws were discovered and iipon 

 what basis they rest. The most that the 



