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interesting illustration of the C02-OrH20 cycle in the atmo~phereis taken from "Chemical Atlas" by Edward L. Youmans and published by Appleton, New York, in 1856. This popular text of a century ago is hand-colored and is a fine example of what the early teacher8 of chemistry in this country made available t o the public. The author, Edward Livingston Youmans (1821-1887), was afflicted with poor eyesight, and he devised a chemical chart to make clear ta the eye the principles and laws of the chemistry of hisera. The book whieh he wrote t o accompany the chart was his "Classhook of Chemistrv." Brief. clear, and devoid of technicalities, i t has an astounding and continuo& sale; it wa8 revised and sold more than 144,000 copies in its three editions. This was truly a remarkable record and would hp envied even in thesedays of widespread chemical instruction. The "Chemical Atlas" was xn extension of the chart method of teaching chemistry. Youmana occupied the chair of chemistry at. Antioch College in 1866. At hie suggestion, the Appletons started Popular Science Monthlyin1872 and he served as itseditor ul was eventually until his health failed. This s u e c e ~ ~ fperiodical merged into the SeienbificAmican. The following excerpts from the text show the charming manner in which the author presents his materials to his readers, who w e presumed t o have been without training in chemistry. "Plants and animals are hoth endowed with living or vital properties; they hoth grow, reproduce their kind, and perish. Yrt the life of these two orders of beings is 0f.a different nature, and depends upon differenb-nay, opposite- condition^. The actions and changes in which vegetable life consists assentially are exactly reversed in the ease of animal life. . . .Plants and animals e m exist only in the sir; this is equally indispensable to both. The relation between the atmosphere and the life of each class is equally intimate and vital, and yet this atmosphere in the two instances performs diametrically opposite offices. "To fix distinctly in the mind the character of the changes wrought by growing vegetation upon the atmosphere, I have ventured again to resort to diagrams, which appeal to theeye. .The effects produced upon the air by the vegetable world are r e p r e
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sented in the left portion of Plate X I . The direotion of the arrows shows carbonic acid and water, as it were, descending from the air, so as to enter the plant, a t the same time that pure oxygen is set free, and rises, as it were, to take their place. I t is not to be supposed, aR the picture might seem to show, that tho plant has any power of sttraoting downward from a dist,ance bh? carbonic acid and water particles or that those particles have anv tendency to doscond from the heights d the atmosphere to vegetable foliage. The diagram is simply designed ta nhow what tho plant receives and what it returns to the atmo~phere.. . . "Animals, it is well known, depend entirely upon vegetnhlos for tho substances which they use rts food. An animal may consume flesh, but bhat, like all obher flesh, comes ultimately from vegetation. The animal cannot,, as the plant does, take ccarhonir wid, water, ammonia, and a few salts, and construct from them it8 own fabric. I t can only receive compounds that have been put together by the vital operations of plant powth, and in a rartain manner transform them into its own substance. "The animal thus undoes the work of the plant. It withdrnna from the air the substance which the plant gave to it, destroy8 the compounds which the plant crested, and returns to the atmosphere those compounds which plants take from it. If the vegetable absorbs carbonic acid from the air, and returns pure oxygen, the animal. on the contram. absorbs oure oxveen. and returns
Form of vapor into the air. "This is shown upon the right side of Plate XI. Pure oxygeu is represented by t,he direction of the arrows s s passing from the atmosphere to the animal world, while carbonic acid and water are restored to the air in its stead; thus exactly reversing the chemical changes whieh are seen to take place between vegetation and the air. The nature of the antagonism between there two orders of life thus becomes apparent a t aglance."
Rams E. OESPER CINCINNATI, OHIO
JOURNAL OF CHEMICAL EDUCATION
