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POPULAR SCIENCE MONTHLY. 



number and variety of the discoveries 

 made in the laboratory by Hofmann 

 but faintly reflect his truly extraordi- 

 nary capacity for hard work; even 

 after passing his seventieth birthday 

 he occasionally worked in the labora- 

 tory 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 govern- 

 ing 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 ex- 

 celled in devising original and brilliant 

 experiments for illustrating these lec- 

 tures; 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). Hof- 

 mann 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 Eugene Chevreul, has 

 as yet appeared. Chevreul was born 

 August 31, 1786, and on the occasion 

 of his hundredth birthday he was pre- 

 sented with a gold medal, with cere- 

 monies 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 contribu- 

 tions to science, numbering 547 differ- 

 ent articles and extending from 1806 

 to 1886. This is, however, incomplete, 

 for Chevreul did not die until April 

 9, 1889, and his literary activity con- 

 tinued to the end. Chevreul's 'Re- 

 searches on Fats' (1823) forms the 

 starting point of one of our great in- 

 dustries 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 Ger- 

 man Chemical Society in 1889. 



One of the greatest benefactions con- 

 ferred on mankind by modern science 

 was the method of manufacturing com- 

 mon soda invented by Nicolas Leblanc. 

 The biography of this little appreci- 

 ated and poorly rewarded chemist was 

 published in 1884 by his grandson, Au- 

 guste Anastass. 



After the outbreak of the Revolu- 

 tion in France the industrial needs of 

 tFe country became more and more 

 pressing, the Academy of Sciences of- 

 fered 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 prac- 

 tical misfortunes, his financial dis- 

 tress, 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 con- 

 tained 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. 



