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PHYSICS AND CHEMISTRY 457
GUSTAV and HEINRICH ROSE, WOHLER, MAGNUS,
ARFV*EDSON and others. He facilitated quantitative
analysis by bringing the blowpipe into more general use,
discovered and described several elements not kriown before
.and made valuable contributions to animal chemistry.
FARADAY worked at the liquefaction of gases and at the
improvement of the steel and glass manufactures, while
DUMAS instituted experiments upon the specific weights of
various gases. MlTSCHERLlCH formed inorganic substances
synthetically and showed that they were identical with the
minerals occurring native; published the results of impor­
tant work upon the combinations of sodium with iodine
and upon the degrees of oxidation of manganese, and, by
his discovery of isomorphism and dimorphism in chemistry,
opened up a branch of the subject having a direct physical
bearing and full of importance for mineralogy. The dis­
covery of the fact that bodies differing'in chemical com­
position may possess the same crystalline form and may
have their constituent elements replaced by others without
•changing such form, whereas other bodies like sulphur may
exhibit different forms while retaining the same chemical
•composition exerted a great influence upon the further
development of chemistry.
With LlEBlG and W6HLER organic chemistry came into
prominence. A field of work was here opened to scientific
research hitherto scarcely, if at all, cultivated. The study
•of organic combinations, their composition and properties,
and the attempt to produce them artificially, constituted a
series of problems, the solution of which has fully occupied
the chemists of the nineteenth century* Then it came to
be recognized how manifold and far-reaching are the rela­
tions between chemistry and practical life, and of what
value that science is in agriculture, in the various handi-
* A. LADENBURG : Vortriige uber die Entwickelungsgeschichte der Chemie
in den letzen hundert Jahren, Braunschweig 1887, S. xijetseq.—H.KOPP:
Die Entwickelung der Chemie in der neueren Zeit, Miinchen 1873, S. 518
•el seq.