PROCEEDINGS OF SECTION J. 725 



Water is an entity of no more complexity, apart from chemical constitu- 

 tion, than hydrogen and oxygen. One might even go so far as to omit 

 the phrase, " apart from chemical constitution," for many elements — 

 for example, carbon — have a more complex constitution than the com- 

 pound water. The common textbook classification of substances 

 based on the periodic classification of the elements produces in the 

 minds of pupils the fallacious idea that an element necessarily has a 

 simpler constitution than a compound. I should like to say here that 

 I have found in my teaching gTeat need for names to distinguish the 

 elementary radicals from the elementary substances. We have many 

 names for compound radicals, but none in general use for simple radicals. 

 Ostwald, in his textbooks, has given names to many simple ions, distinct 

 from the names of the elements themselves, but they are largely metallic 

 ions. Thus water is a compound of 1 1 per cent, hydryl and 89 per cent, 

 oxyl, applying these names to the simple radicals H and 0. Water 

 is a compound of hydryl and oxyl ; oxygen is a compound of oxyl with 

 itself, so hydrogen is a compound of hydryl with itself. A dilute 

 solution of hydrochloric acid contains free hydryl, but not free hydrogen. 

 The atomic weights refer to the radicals sulphyl and phosphyl, and not 

 to the known solids. 



I will briefly describe what I have found to be a good way to get 

 pupils to appreciate the more important principles of chemistry by 

 working in the laboratory. The pupil is given some hydrochloric acid, 

 a substance of common occurrence outside the laboratory ; then he 

 is given some zinc, a material with which he is already familiar, and he 

 has to dissolve the zinc in the acid. This leads to a knowledge of 

 hydrogen incidentally, and to that of zinc chloride mainly. He is 

 given other metals to test in the same way, to find out which, like zinc, 

 are soluble, and, in the case of the soluble metals, to extract their 

 chlorides. Then he studies the action of acids on litmus, he is given 

 sodium hydroxide to neutralise and extract sodium chloride. The 

 nature of alkalies is dealt with. Ammonium chloride is prepared, 

 ignited, and also mixed with lime. 



A metallic oxide, such as copper oxide, is next dissolved in the 

 acid, and the copper chloride obtained. Also a metallic hydroxide, 

 such as that of iron dissolved up, and the chloride extracted. 

 Then a metallic carbonate is dissolved, and the chloride obtained. 

 Lastly lead chloride is obtained by precipitation, and the pupil finds out 

 what other chlorides may be obtained in this way. With those 

 chlorides which he finds insoluble he tries the solvent action of given 

 liquids, by which he works out the means of distinguishing them. So 

 far this work is systematised under five modes of forming metallic 

 chlorides. 



Then he obtains potassium chloride from chlorate, with the object 

 of observing the properties of oxygen. He next performs the reverse 

 process, namely, obtaining the acid from the chloride, and then by 

 oxidation generates chlorine. The chlorides are finally compared with 

 one another. 



