Page:Popular Science Monthly Volume 61.djvu/484

478 number and variety of the discoveries made in the laboratory by Hofmann but faintly reflect his truly extraordinary capacity for hard work; even after passing his seventieth birthday he occasionally worked in the laboratory until two or three o'clock in the morning.

One of Hofmann's most valuable series of investigations was his study of coal-tar derivatives; begun in 1845 it reached a lofty point in 1858 and culminated in the discovery of a long line of magnificent dyes whose hues and names have become household words; it is true that all aniline colors are not Hofmann's own, but he worked out the fundamental principles governing their existence, and pointed out the way for their creation by the labors of his pupils and others. Hofmann was an energetic and agreeable lecturer to classes in the university and he excelled in devising original and brilliant experiments for illustrating these lectures; some of these he made known through his 'Introduction to Modern Chemistry,' published in 1865, and in articles contributed to the Berichte in succeeding years (1871-1882). Hofmann was married four times and had eleven children born to him, eight of whom survive him. The biography is illustrated by two portraits of the eminent chemist, one representing him in the twenty-eighth year, and the other in the seventy-third year of age.

It is rather singular and hardly creditable to French authors that no adequate biography of the centenarian chemist, Michel Eugène Chevreul, has as yet appeared. Chevreul was born August 31, 1786, and on the occasion of his hundredth birthday he was presented with a gold medal, with ceremonies that included addresses from men of distinction. An account of this function was published at Rouen, in 1886, illustrated by an engraved portrait of the veteran chemist and with a facsimile of the medal. In the same year there appeared at Paris a full catalogue of Chevreul's contributions to science, numbering 547 different articles and extending from 1806 to 1886. This is, however, incomplete, for Chevreul did not die until April 9, 1889, and his literary activity continued to the end. Chevreul's 'Researches on Fats' (1823) forms the starting point of one of our great industries and his essay on 'Colors—their Application to Industrial Arts,' has borne valuable fruit. An obituary of Chevreul by A. W. von Hofmann appeared in the Reports of the German Chemical Society in 1889.

One of the greatest benefactions conferred on mankind by modern science was the method of manufacturing common soda invented by Nicolas Leblanc. The biography of this little appreciated and poorly rewarded chemist was published in 1884 by his grandson, Auguste Anastass.

After the outbreak of the Revolution in France the industrial needs of the country became more and more pressing, the Academy of Sciences offered a prize of 12,000 livres for a practical method of manufacturing carbonate of soda from common salt; this problem attracted the attention of a modest physician devoted to chemical studies, Nicolas Leblanc. The history of his chemical success, and his practical misfortunes, his financial distress, and his shocking death by his own hand make very sad reading; this tragic event occurred in 1806.

An appendix to this biography has also a sad interest; it is an inventory of the apparatus and chemicals contained in the laboratory of Lavoisier, made five months after his execution, and signed by Nicolas Leblanc.

Henry Morton, who died May 9, 1902, will be best remembered as a physicist, but he began his scientific career as a professor of chemistry. An artistic and beautifully illustrated 'Biographical Notice of Dr. Morton' forms a volume prepared by his friends, Coleman Sellers and Albert R.