22 OCTOBER 1881, Page 22


from the majority of the very numerous little manuals of laboratory instruction which have been produced during the last few years. Of course, the simple experiments in chemistry and chemical physics

with which the booklet opens present no feature of novelty. Bat in chapter ii., we have an example of the special kind of chemical

experiment by which Dr. J. Emerson Reynolds introduces his pupils to the great doctrines of "definite proportions " and " constant com- positions," using for this purpose the decomposition of silver nitrate by heat and by magnesium. These experiments might be performed by beginners successfully ; we doubt if the delicate apparatus em- ployed for ascertaining the weight of hydrogen disengaged by the action of a known weight of magnesium upon sulphuric acid could be made to yield satisfactory results, except in trained hands. The same doubt may be expressed with regard to the experimental comparison of the specific beats of silver and magnesium (p. 59). But, although there are difficulties in the way of any teacher trying to make his pupils carry out the minute and careful instructions of Dr. Reynolds, and although we feel sure that it would prove im- practicable to furnish the necessary materials and apparatus for many of the experiments to each member of a large class, yet we are sure that many important hints may be gained from this book. The originality of the work will make it of value as a book of suggestions for the intelligent teacher.