Page:Popular Science Monthly Volume 49.djvu/885

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861
FRAGMENTS OF SCIENCE.

paints are very stable, but their protecting power is not great. Herr Spennrath has attempted to explain the duration of different paints by means of comparative experiments on sheets of zinc. The painted zinc was dissolved in an acid, and films of paint were obtained and subjected to various tests. AH were rapidly destroyed by the action of dilute hydrochloric or nitric acid, and of the vapors of sulphuric and acetic acids. Alkaline vapors likewise destroyed them rapidly. Pure water acts more rapidly than salt water, which goes to prove that corrosion by sea water is rather an effect of mechanical washing than of chemical action. Temperature, too, has a considerable influence on the resistance of paints. The films became brittle at a temperature of 95° C, and a perceptible contraction of the layer took place. Similar effects were produced on paints exposed for a long time to a low temperature.

 

August Kekulé.—August Kekulé, Professor of Chemistry in the University of Bonn, who died July 13th, sixty-six years old, left his mark on the science of chemistry in a distinct advance to which he gave the impulse. He was born at Darmstadt, in 1829, went to school there, and was then sent to Giessen, under the expectation that he would be educated to become an architect. But Liebig was at Giessen, and Kekulé's attention was turned to chemistry. Returning to Darmstadt, he studied chemistry under Moldeuhauer, and then entered again as a student at Giessen under Liebig and Will. He afterward studied in Paris; sojourned for a short time in Switzerland as assistant to Von Plantu, at Reichenau; was engaged at St. Bartholomew's Hospital in London; established a laboratory, where he received pupils, at Heidelberg; and became professor, successively, at Ghent and Bonn. Kekulé's services to chemistry were chiefly in the theoretical field. The twenty-fifth anniversary of his promulgation of the benzene theory was celebrated at Berlin, in 1890, and the twenty-fifth anniversary of his professorship at Bonn, in that city, two years later. He took up Frankland's theory of valency and elaborated it; laid the foundation of the study of constitutional chemistry; gave the start to the fruitful investigation of the carbon compounds; and pointed the way to thousands of important experiments and was the inspiration of hundreds of valuable discoveries.

 

Drawing Upside Down.—Observations of children drawing upside down have been collected by Mr. Rina Scott, who says, in Nature, that a great many children draw in this way, while many from the first draw the right way up. He relates that a boy of four, when asked to draw a rook on a haystack, began at the bottom of the paper with the rook's back, and gradually worked his way up to the haystack; then turned the drawing round and asked his observer to look at it—evidently realizing that it was inverted. Mr. Scott does not find the explanation of the peculiarity in any inversion of the retinal image; for, if a child who draws upside down when drawing on a horizontal table, is asked to draw on a blackboard placed vertically, he will draw everything the right way upward. He supposes that when the object seen on a vertical plane is to be represented on paper placed in a horizontal plane—in which there is already a considerable divergence from the real appearance—it is simply a matter of convenience to him at which end he begins—both being equally wrong from his point of view. So children sometimes look at picture books upside down, and small children are more ready to draw objects which they have been accustomed to see in a horizontal plane, than erect objects. Mr. Alfred W. Bennett relates that he has been able all his life to read easily a book upside down, so that it makes no difference to him which way the book is presented. This is because, as he has been told, he first learned to read, upside down, by standing in front of a brother and looking over the top of the book from which he was being taught to read. The facility curiously extends to books in foreign languages, even those in which other alphabets—as Greek and Hebrew—than the Roman are used, and to nearly the same extent to handwriting. Li a similar connection Mr. Hiram M. Stanley speaks of a strong native tendency in some children—and he might have added adults, for we have seen sign-painting in which that style was present—to reverse right and left in drawing such letters as J and L. He compares this confusion, and probably is