AUGUST WILHELM VON HOFMANN. 417 



were three of the most important classes of chemical compounds 

 discovered, — the secondary and tertiary amines, and the substi- 

 tuted ammoniums, — but also this discovery had a great, an 

 almost decisive influence on the adoption of the present chemical 

 theories. This was one of his earliest researches, and it is 

 interesting to note that in the later years of his life he added 

 still another way of preparing primary amines to the meagre list 

 of known methods; it was by the action of bromine and water 

 upon the amides, and has rendered these very expensive sub- 

 stances more accessible. 



Another discovery, the displacement by heat of hydrocarbons 

 from substituted amnionic hydrates, dates also from his later 

 years, and promises to be of the first importance, since it has 

 already done much, and will do more, to solve the perplexing 

 riddle of the constitution of the natural alkaloids. 



Of his other important discoveries I shall not attempt to speak 

 in detail; they include syntheses of the mustard oils and guani- 

 dine, with the working out of the constitution of these products 

 of life; the migration of alkyl radicals from nitrogen to carbon 

 under the influence of heat, an interesting observation which has 

 been of great value in the color industry; and researches on the 

 isonitriles, cedriret, orthoamidomercaptans, cyanuric acid, the 

 ethylene bases, and many other substances natural and artificial. 

 And here should also be mentioned the new forms of apparatus 

 contrived by him, especially that for determining vapor densi- 

 ties, and the eudiometers and other pieces of lecture apparatus 

 to which I have alluded earlier. 



In the preceding description of the man and his work I have 

 tried to portray his vigorous, enthusiastic energy, and his ex- 

 ceeding kindliness, which also appeared in his family life, mak- 

 ing him at the same time a most affectionate and ambitious 

 father. His wonderful inventiveness and intellectual power 

 also have been sufficiently shown by the account of his discov- 

 eries, and his great administrative ability by his success in 

 organizing and carrying on the large chemical laboratories of 

 London and Berlin. The picture of Hofmann would be incom- 

 plete, however, without mention of his breadth of character. He 

 always deplored the unfortunate quarrel between German and 

 French chemists, which followed the Franco-Prussian war, and 

 through it all kept up the most friendly relations with the 

 leaders of French chemistry. An even better proof of this 

 vol. xxvin. (v. s. xx.) 27 



