Page:Popular Science Monthly Volume 30.djvu/714

 692 work already carefully thought out, which should give the synchronous progress of invention, discovery, and learning, from the beginning of recorded history. Many months and a great deal of labor were devoted to research in the various public libraries, and when the undertaking was far advanced toward completion it was forestalled by another work covering substantially the same ground. This was a bitter disappointment, but, wasting no time in regrets, Edward was soon at work on an arithmetic, in which the problems were made up from the constants of science. This enterprise also was anticipated by another book of similar character. But the labor thus bestowed was not wholly lost; for it helped to educate him in the line of his future work.

Although occupied most of the time as above stated, my brother kept up the study of agricultural chemistry, and, to this end, ever since my arrival in the city he had been seeking for a laboratory where I could enter as a pupil; but none was found that would admit a woman, until Dr. Antisell, one of the Irish exiles of 1848, consented to receive me. Here I at once began the studies preliminary to the analysis of soils. By the time I was able to make such analyses, my brother had become convinced that they were of no value in practical agriculture. But, in our talks over this laboratory experience, he was still hindered by the old difficulty of dealing with chemical phenomena at second-hand; and now an unexpected consequence followed. When he reflected that chemistry was fast becoming a popular branch of education, and that, so far as its processes were concerned, the youths who were studying it might be classed, along with himself, as blind, their situation naturally interested him. Occupied with this subject, there one day arose in his mind a scheme for picturing atoms and their combinations that would bring the eye of the student into more effectual service. Out of an impulse to help this unfortunate class came the “Chemical Chart,” in which he succeeded in making clear to the eye, and easily remembered, the most important principles and laws of the science as it was then understood. This “Chart” represented the principal elements, binary compounds, and salts, and the minerals of chief interest to geologists and agriculturists, together with the most important organic bodies. Atoms of the different elements were shown by diagrams of different colors, the relative sizes of which expressed their combining ratios, and the compounds exhibited the exact numbers of the respective atoms that unite to form them. The chart was at once accepted as a valuable assistance in teaching chemistry by many leading educators throughout the country, and its use led to frequent requests that its author would prepare a book to go with it. The text-books consulted in its preparation had left the impression that this science was not so attractively presented to the learner as it might be. He thought that chemistry could be made enticing as well as intelligible to learners who had not the help of experiments in its pursuit.