I hope that the success of your Class-Book will be proportionate to its merits, and that your efforts to diffuse the knowledge of Chemistry will be duly appreciated by the friends of education. _From_ PROF. J. MULLIGAN, _Principal of Young Ladies' School, New York_. We have a large number of school-books for the purpose of giving elementary instruction in Chemistry--possessing various kinds and various degrees of merit; but of all which I have examined, I should prefer the Class-Book of Chemistry, as the most perspicuous in style and method, and as containing the happiest selection of what is most interesting, and most practically valuable in the vast field of chemical science. _From the N. Y. Commercial Advertiser._ Either for schools or for general reading, we know of no elementary work on Chemistry which in every respect pleases us so much as this. _From the Scientific American._ Such a book, in the present state of chemical science, was demanded; but to present the subject in such a clear, comprehensive manner, in a work of the size before us, is more than we expected. The author has happily succeeded in clothing his ideas in plain language--true eloquence--so as to render the subject both interesting and easily comprehended. The number of men who can write on science and write clearly, is small; but our author is among that number. Chemical Chart: BY E. L. YOUMANS. On Rollers, 5 feet by 6 in size. New Edition. Price $5. This popular work accomplishes for the first time, for Chemistry, what maps and charts have for geography, geology, and astronomy, by presenting a new and valuable mode of illustration. Its plan is to represent chemical composition to the eye by colored diagrams, so that numerous facts of proportion, structure, and relation, which are the most difficult in the science, are presented to the mind through the medium of the eye, and may thus be easily acquired and long retained. The want of such a chart has long been felt by the thoughtful teacher, and no other scientific publication that has ever emanated from the American press has met with the universal favor that has been accorded to this Chart. In the language of a distinguished chemist, "Its appearance marks an era in the progress of the popularization of Chemistry." It illustrates the nature of elements, compounds, affinity, definite and multiple proportions, acids, bases, salts, the salt-radical theory, double decomposition, deoxidation, combustion and illumination, isomerism, compound radicals, and the composition of the proximate principles of food. It covers the whole field of Agricultural Chemistry, and is invaluable as an aid to public lecturers, to teachers in class-room recitation, and for reference in the family. The mode of using it is explained in the class-book. _From the late_ HORACE MANN, _President of Antioch College_.