246 BEPORT— 1889. 



exposed to the air becomes liquid. If it is an analogous substance to 

 slaked lime, it should combine with chalk gas and be reconverted into 

 soda ; this is found to be the case. Caustic soda is thus discovered. 

 Chalk and lime are known to neutralise acids ; both soda and caustic 

 soda are found to do so, and their effect on vegetable colours is found to 

 be the reverse of that of acids. At this stage the origin of the name 

 alkali is explained, and it is pointed out that the oxides which have been 

 studied may be arranged in two groups of alkali-like or allcylic and 

 acid-forming or acidic oxides, the former being derived from metals, the 

 latter from non-metals. The production of salts by the union of an oxide 

 of the one class with the oxide of the other class is then illustrated by 

 reference to earlier experiments. 



The point is now reached at which the results thus far obtained may 

 be reconsidered. The student has been led in many cases to make 

 discoveries precisely in the manner in which they were originally made ; 

 and it is desirable that at this stage, if not earlier, the history of the 

 discovery of the composition of air and water, &c., should be briefly 

 recited. It is then pointed out that a variety of substances have been 

 analysed and resolved into simpler substances — air into oxygen and nitro- 

 gen, water into oxygen and hydrogen, &c. ; and that these simpler sub- 

 stances thus far have resisted all attempts to further simplify them, and 

 are hence regarded as elements. A list of the known elements having 

 been given, the diverse properties of the elements may be illustrated 

 from the knowledge gained in the course of the experiments. The fact 

 that when elements combine compounds altogether different in properties 

 from the constituents are formed also meets with manifold illusti'ation. 

 Too little has been ascertained to admit of any general conclusion being 

 arrived at with regard to the proportions in which elements combine, 

 but it is clear that they may combine in more than one proportion since 

 two oxides of carbon have been discovered, and in the only cases 

 studied — viz. copper oxide and chalk — the composition has been found 

 not to vary. The existence of various types of compounds has been 

 recognised, and a good deal has been learnt with reference to the nature 

 of chemical change. But, above all, the method of arriving at a know- 

 ledge of facts has been illustrated time after time in such a manner as to 

 influence in a most important degree the habit of mind of the careful 

 student. New facts have been discovered by the logical application of 

 previously discovered facts : the habitual and logical use of facts has 

 been inculcated. This is all-important. It has become so customary 

 to teach the facts without teaching how they have been discovered 

 that the great majority of chemical students never truly learn the 

 use of facts ; they consequently pursue their daily avocations in a 

 perfunctory manner, and only in exceptional cases manifest those quali- 

 ties which are required of the investigator ; their enthusiasm is not 

 awakened, and they have little desire or inclination to add to the stock 

 of facts. It must not for one moment be supposed that the object of 

 teaching chemistry in schools is to make chemists. Habits of regu- 

 lated inquisitiveness, such as must gradually be acquired by all who 

 intelligently follow a course such as has been sketched out, are, however, 

 of value in every walk of life ; and certainly the desire to understand all 

 that comes under observation should as far as possible be implanted in 

 everyone. 



