'An experiment with distilled water gives less acid and alkali;

'Therefore sometimes with less impurity we have less acid and alkali.'

V. 'The contact of moist hands' may be an additional cause of the residual phenomenon.

Improved syllogism in AAI, Fig. iii., to include this

concurrent cause.

'An experiment with distilled water and apparatus kept from contact of hands will admit still less impurity,

'An experiment, &c., results in the production of still less acid and alkali;

'Therefore sometimes with still less impurity we have still less acid and alkali.'

VI. Amended syllogism, AAA, Fig. iii.

'A case where we use these precautions in vacuo is a case of no impurity,

'A case where we use, &c., in vacuo is a case of no acid and alkali;

'Therefore a case of no impurity is a case of no acid and alkali.'

VII. Immediate inference from last conclusion.

Cases of no-impurity are cases of non-production of acid and alkali,

'Therefore' (according to the example in Division II. of inference from A)

'All cases of production of acid and alkali are cases of some impurity ;'

Which was to be proved."

was nitrous acid. He thought the nitrogen required for the production of both the acid and alkali came from the air dissolved in the water; he therefore finally boiled the water to expel the air it contained, and conducted the experiment in an atmosphere of pure hydrogen; that was the crowning point of his discovery, for no acid or alkali appeared when the experiment was made under these conditions.

Chemistry as long as it is taught by the present methods will never prove of any value in afterlife to those who study it as a branch of general education; it will only prove of value to those who study it as a profession, and even the latter might become sooner and better acquainted with it than at present. But I contend that even those who only study it as a branch of general education ought to, and would, be able, if it were taught in a rational manner, to make use of it in after-life, as they can arithmetic and the other subjects they were taught at school. But by the present system a multitude of disconnected facts are tumbled into the learner's mind; the majority they will never remember, and the rest will be mere lumber, for they will prove of no practical use. What the general student requires to know, and what the teacher ought to impart to him, is a general knowledge of the science, a knowledge of its leading links, a knowledge not superficial but thorough, so as to have a true conception of the subject in its great features, leaving the study of the minor details to those who are to employ it in some special avocation in the future.

252

LECTURE VI.

On the Teaching of Qualitative Analysis in Secondary Schools -A valuable Study for Disciplining the Mind when taught in accordance with the Laws of Thought-What can be accomplished in Teaching Boys Chemistry, and to what extent it can be carried on in Secondary Schools-The After Effects of a Sound System of Chemical Instruction in Schools-The Cost of Teaching it in Schools-The Difference between Exact Knowledge, though limited in extent, and Superficial Acquirements illustrated-Cardinal Newman on the Teaching of a Multitude of SubjectsSmatterers in Science most Injurious in Industrial Establishments On Technical Language Popular Science Lectures.

If the study of Chemistry is pursued beyond teaching what is termed Elementary Chemistry, and which has been described in the last Lecture, qualitative analysis is the next branch of the science now all but universally taught in schools of general education as well as in schools or colleges of science. If teachers of the science were asked with what object this branch was taught in schools, they would, if they were guided by the way that most books on the subject are written, almost invariably answer to teach the boys how to test or analyze substances. It would rarely be stated: "I am afraid that the reason for making it a

branch of general education is, or ought to be, that it forms such an admirable discipline for the mind when taught in accordance with the laws of thought."

Most of the boys who are taught Chemical Analysis in schools will never have any occasion to make an analysis in after-life. The object of the study ought to be, as that of all other school studies, to assist in training and developing the mind; and the system of instruction which best accomplishes this is the best for teaching the subject itself.

No school, still less a college, which professes to educate ought to employ the mere testing books; and the books of Tables are not much better; for the system is purely mechanical, for by directing all that has to be done, by telling this and showing that, the learner is made a mere recipient; it takes away from him the necessity for, or rather prevents him, exercising his judgment, and it relieves those teachers who are not earnest in the work of instruction of the most essential part of their duties, for the analytical tables alluded to allow teachers to adopt that "repeating by rote system," in another form, which is yet far too prevalent in our schools. The Giessen outlines and Fresenius are excellent, especially the latter, as reference books; but the plan on which they are constructed does not, in my opinion, render them suitable as educational

books, and the attenuated copies of them which are now appearing can only perform one office for the learner-they can cram him for an examination.*

In qualitative analysis we have, in my opinion, a most valuable instrument, not only for training the mind, but for teaching the science, independent altogether of its value of enabling one to ascertain what elements are present, and in what state of combination, in any unknown compound or mixture. Of all the reforms the late Baron Liebig introduced in the teaching of the science, the most valuable one, I believe, was the systematic course of qualitative analysis which formed an essential part of the plan of teaching pursued at Giessen. The old method of teaching consisted in setting the student to work at quantitative analysis as soon as he entered the laboratory. An eminent chemist informed me some years ago that when he entered, as a student, an English laboratory, the first thing he was set to do was to estimate the quantity of copper as oxide in a given quantity of sulphate. The Assistant afforded him assistance in the precipitation, and, having given him a filter, told him to throw the precipitate upon it. The student, without more to do, spread the filter upon

Mr. Spencer Baynes, in his preface to the Port-Royal Logic, observes, "In reading over the book again, I have been struck afresh with its special fitness to serve as a text-book in the work of higher instruction. While one of the worst books for cramming, it seems to me to be one of the very best for educating the mind."