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THURSDAY, JANUARY 19, li 



THE TEACHING OF ELEMENTARY 

 CHEMISTRY. 



Elementary Chemistry. By M. M. Pattison Muir, M.A., 

 Fellow and Praelector in Chemistry of Gonville and 

 Caius College, and Charles Slater, M.A., M.B., 

 formerly Scholar of St. John's College, Cambridge. 



Practical Chemistry: a Course of Laboratory Work. 

 By M. M. Pattison Muir, M.A., and Douglas Carnegie, 

 B.A., Demonstrator of Chemistry, and formerly Scholar 

 of Gonville and Caius College. (Cambridge, at the 

 University Press, 1887.) 



DURING the past few years numerous expressions 

 of dissatisfaction have been more or less openly 

 uttered by members of the younger generation of English 

 chemical teachers, and the opinion is gaining ground 

 that instruction in the elements of the science can no 

 longer be imparted entirely on the stereotyped lines of 

 practice devised to suit the requirements of a bygone 

 generation— of a time when a science of chemistry was 

 but beginning to exist, and the conviction had not yet 

 been acquired that the subject must ultimately be 

 reckoned as a necessary element of a liberal education. 

 Several of the objectors have advanced their criticisms to 

 the constructive stage, thereby rendering great service to 

 the cause ; nevertheless we believe it is the general opinion 

 that, although each contains numerous good points, all 

 the schemes hitherto advanced are in the main failures, 

 and that it is impossible to accept any one as it stands. 

 The senior author of the works now under notice has 

 been one of the most active objectors to the good old- 

 fashioned style of teaching, and has told us in terms 

 somewhat vague and general it is true, but none the less 

 plainly, what we ought to do. Even chemists recognize, 

 however, how comparatively easy it is to preach and yet 

 how difficult to practice, and we have therefore patiently 

 awaited the publication of details to guide us on the 

 tortuous and narrow path to success. These details are 

 now before us in the two books of which the titles are 

 given at the head of this article ; " they are intended to 

 be used together," say the authors, and " their object is 

 to teach the elements of chemical science." What will be 

 the verdict of, say, a jury of schoolmasters — by far the 

 most competent judges on such a question — as regards 

 the merits of the scheme put forward by Messrs. Muir, 

 Carnegie and Slater? We venture to predict, and we 

 trust, that it will be, " Impossible." In order to justify 

 this statement we shall proceed to specify our objections 

 to the scheme, trusting that, by so doing, some service 

 may be rendered to a cause in which so many are now 

 deeply interested, and which is undoubtedly of the highest 

 importance to the community on account of the inestim- 

 able advantages to be derived from the teaching of the 

 elements of experimental science, and especially of 

 chemistry, in schools in a logical and systematic manner. 

 The issue of two companion volumes has many 

 advantages : indeed we believe that in the future it will 

 be thought essential to separate the instructions to a 

 student stating what is to be done from any description 

 Vol. XXXVII. — No. 951. 



or discussion of observations or inferences to be deduced 

 from results, in order, as far as possible, to induce the 

 habit of observing and of reasoning from observation ; in 

 no other way probably is it possible to force the student 

 to become an independent observer and thinker, and to 

 prevent the teaching of science from degenerating into 

 mere cram, as is too frequently the case in schools. It 

 appears to us, however, that in the earlier part of the 

 "Practical Chemistry" Messrs. Muir and Carnegie do 

 not sufficiently bear in mind their own intention, and that 

 much of the matter would find a more fitting place in the 

 companion volume. 



In the " Practical Chemistry," we learn from the 

 preface, " the aim has been to arrange a progressive course 

 in which, as the experiments become more difficult, the 

 reasoning becomes more close and accurate." But 

 surely, in a scientific work, the reasoning should through- 

 out 'be " close and accurate : " authors who make such a 

 statement almost invite suspicion, and it is to be feared 

 that in this case such suspicion is unfortunately not 

 entirely unwarranted ; the reasoning is indeed but rarely 

 close, and not infrequently conspicuously absent. As a 

 typical case, and as an illustration of the manner in 

 which the experiments are usually set forth, Experiment I, 

 Chapter VI., p. 22, may be quoted : — 



" Place a small piece of sodium in a little cage of wire- 

 gauze attached to a glass rod. Fill a large test-tube with 

 water and invert it in a small basin of water ; hold the 

 tube with one hand, and with the other bring the wire 

 cage containing the sodium under the water, so that the 

 gas, which at once begins to bubble through the water, 

 passes into the tube and collects there. When the tube 

 is full of gas, cover the mouth with the thumb, invert the 

 tube, and bring a lighted taper to the mouth ; the gas 

 takes fire, and burns with a pale, almost non-luminous 

 flame — the gas is hydrogen. Evaporate the water in the 

 basin to dryness ; the white solid which remains is a 

 compound of sodium, hydrogen, and oxygen ; it is called 

 sodium hydroxide, or caustic soda. (The composition of 

 this compound cannot be proved at present.) By the 

 interaction of sodium and water, hydrogen and a com- 

 pound of sodium with hydrogen and oxygen have been 

 formed. Sodium is an element : if this is taken as proved, 

 it follows that the hydrogen evolved as gas in the fore- 

 going experiment, and also the hydrogen and oxygen 

 which combined with the sodium, must have formed part 

 of the water at the beginning of the experiment. {Here we 

 assume that the material of the vessel was not chemic- 

 ally changed during the process.) Water therefore is a 

 compound of hydrogen and oxygen." 



What can be the educational value of an experiment 

 thus described and discussed } That water therefore is 

 a compound of hydrogen and oxygen only follows when 

 a variety of assumptions are made. The tendency of 

 such teaching is entirely in the wrong direction : the 

 habit of assuming that such and such is the case is one 

 which it is all-important to counteract by experimental 

 teaching, and practical chemistry will never be of value 

 as a rigid mental discipline unless the student be led 

 from the beginning to demand and obtain proof of each 

 successive link in a chain of arguments. 



Again, the directions for Experiment 3, Chapter II., p. 7, 

 are to heat copper in dried air, and to weigh the tube con- 

 taining it before and after heating ; the weight is found 

 to increase, whence it follows that the metal has combined 



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