originally had the significance of ‘test.’ The thing is quite on a par with the alleged medical advice to “stuff a cold and starve a fever.” T!.l!dt-?’ 1). ~{OJiL~l’Ojf
A Laboratory Outline of General Chemistry. B!, .4kxu?!dcr h i i f / ? , Third Edzf2’o)i. Ra;l?t.#i i l l C ‘ ~ J ~ ~ ~ l l h O l ’ U f;if)/ ~ O ~ i T I - i l ~ ~ U n .I. f Halt.. I 2 X 1 9 C t i i ; pfi. ; I ? - r,{b, 1 , i r k : Tire i ‘ i . r i t i c l ’ j ’ ( ‘ o . , rqo;.---h the preface the authors say :
“\\.lien quantitative experiments were first used in elementary chemistry it \vas hoped t h a t they would also assist in developing a n abiding realization of the quantitati~-enessof all chemical phenomena and, as a consequence. make all the thought and work of the student more rigorous. I n the experience of the authors. however. quantitative experiments of the usual kind fail to accomplish this important result. Students who have performed such experiments still add a test-tube full of sulphuric acid to a liquid known to contain only a trace of a compound of lead, and still think less than a dozen bubbles of hydrogen sulphide sufficient to precipitate the lead from I O cc. of approximately normal lead nitrate solution. They attempt to make potassium chlorate without considering that a few bubbles of chlorine (perhaps liberally mixed with air) will not saturate three grams of potassium hydroxide, or they take too much water and then, not having considered the solubility and, therefore, not knowing what is wrong, throw away the product and lose valuable time by starting entirely a b initio. The failures which result from this lack of a sense of quantity are innumerable, and the discouragement often a serious hindrance to ultimate success. The fault, of course, is in the instruction, and the remedy lies in exercises and questions devised to cultivate this missing sense. It is to meet this situation t h a t the rables of solubilities have been introduced and have been referred to frequently. With the same object, the tables of degrees of ionization have been utilized and the varying degrees of activity of acids have been observed and measured. Still further to cultivate rational experimentation, the solutions on the side-shelf should be approxiniately normal (or in simple multiples or submultiples of this concentration), and the student may then be led to note the concentrations and, in many experiments, to take suitable quantities accordingly. The importance of this point of view indicated in the foregoing can hardly be overestimated. Genuine success in business or in the professions, and often the mere making of a livelihood, depend so largely on ability to reason quantitatively t h a t practice in this kind of reasoning is of inestimable value in education. If, on the contrary, the work i n chemistry is purely haphazard in this respect, the study of the science m a y easily be a positive detriment rather than a benefit, and t h a t whether the student ultimately makes direct use of his knowledge of the science or not. “If i t appears t h a t these changes have made the work more difficult, it must be remembered that valuable knoivledge can be obtained only by effort, and that the value of the knowledge is in proportion to the effort, provided the latter is directed rationally along instructive lines. Easy chemistry must be superficial and empirical, in proportion ito its simplicity. It is easy to perform experiments mechanically ; i t is necessarily more dificult to interpret the results and extract all that they can teach.”
New Books
588
If the use of this book in the laboratory will cause the student to think, the book will mark the beginning of a new epoch. Even if i t should not d o a s much as that, i t is important to cultivate the sense of quantity. The wide scope of the experiments may be inferred from the fact t h a t the authors have included a modification of Buchholz’s experiments with tin, stannous chloride and water, p. 119. IPzlder D . Bancroft ’ Introduction a 1’ ktude de 1’ Electricit6 statique et de Magnetisme. B y E . Bichat and R. Blondlot. Dezocie‘me Bdition, eiztibrement rejondue. 14 X 23 c m ; pp. viii 188. Paris: Gautizier-Villars, 1907. Price: paper, 5 jrancs.-In the first part, on static electricity, the chapters are entitled: fundamental phenomena; action of two electrified masses, one on the other; definitions; theorem of Gauss; potential; experimental study of the electric field; tubes of force and lines of force; propositions in regard to conductors; electrical diagrams ; electrical equilibrium ; capacity; condensers; work and electrical energy; derived units and the C. G. S.system; electroscopes and electrometers; applications of electrometers ; electrical machines ; specific inductive power ; electric spark; decay of a n electrical charge. I n the part on magnetism, less than forty pages, the chapters are entitled: magnets and magnetic field; laws of magnetic repulsions and attractions ; terrestrial magnetism. The book is avowedly elementary, and is intended to meet the requirements for entering the kcole Polytechizique. On p. 13 the authors give a reproduction of a cut from Coulomb’s original memoir. Tl.ilder D . Bancrojt
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Le Principe de la Conservation de 1’Assise et ses Applications. B y Georges ,\latisse. 16 X 25 c m ; p p . 65. P a r i s : A . Hermann, 1907. Price: paper, 2.50 jraizcs.-Instead of considerinng the diflerent forms of energy as the products of the potential into the capacity, the author prefers to use the word assise instead of capacitb. .4s capacity factors for different forms of energy, he takes the quantity of electricity, the entropy, the volume, the distance, the quantity of matter which is measured by the mass. The author’s law of the constancy of the capacity factors rests on the following facts. I . Tn a n isolated system the total quantity of electricity remains constant. 2 . I n a reversible transformation constituting a closed cycle, the change of the entropy is zero. 3. The mass of a system in an enclosed space remains constant no matter what physical or chemical changes take place. 4. If a system is enclosed in a rigid envelope, the volume remains constant no matter what physical or chemical changes take place. j. The rectilinear distance between two fixed points remains constant even though the relative positions of movable points along the line ma.y change. The “law” can be formulated in the following way: “Physical and chemical changes do not create electricity, space (cubical or linear), entropy, or matter.” Comment would seem to be unnecessary. Il’ilder D . Bancrojt
