he made water by burning hydrogen
in oxygen (see cavendish, henry). He
also devised a rational nomenclature
for chemical compounds. In 1794 he
was tried by the Jacobins as an oppo-
nent of the Revolution (because of
his tax-gathering), found guilty, and
guillotined.
law of chemical equilibriumSee
equilibrium constant.
law of conservation of energy
See conservation law.
law of conservation of massSee
conservation law.
law of constant composition See
chemical combination.
law of deÜnite proportions See
chemical combination.
law of mass actionSee mass ac-
tion.
law of multiple proportions See
chemical combination.
law of octaves (Newlands’ law)
An attempt at classifying elements
made by John Newlands (1837–98) in
- He arranged 56 elements in
order of increasing atomic mass in
groups of eight, pointing out that
each element resembled the element
eight places from it in the list. He
drew an analogy with the notes of a
musical scale. Newlands’ octaves
were groups of similar elements dis-
tinguished in this way: e.g. oxygen
and sulphur; nitrogen and phospho-
rus; andÛuorine, chlorine, bromine,
and iodine. In some cases it was nec-
essary to put two elements in the
same position. The proposal was re-
jected at the time. See periodic table.
A
- John Newlands’ paper
law of reciprocal proportions
See chemical combination.
lawrencium Symbol Lr. A radio-
active metallic transuranic element
belonging to the *actinoids; a.n. 103;
mass number of theÜrst discovered
isotope 257 (half-life 8 seconds). A
number of very short-lived isotopes
have now been synthesized. The el-
ement was identiÜed by Albert
Ghiorso and associates in 1961. It
was named after E. O. Lawrence
(1901–58).
A- Information from the WebElements site
laws of chemical combination
See chemical combination.
laws, theories, and hypotheses
In science, a law is a descriptive prin-
ciple of nature that holds in all cir-
cumstances covered by the wording
of the law. There are no loopholes in
the laws of nature and any excep-
tional event that did not comply with
the law would require the existing
law to be discarded or would have to
be described as a miracle. Epony-
mous laws are named after their dis-
coverers (e.g. *Boyle’s law); some
laws, however, are known by their
subject matter (e.g. the law of conser-
vation of mass), while other laws use
both the name of the discoverer and
the subject matter to describe them
(e.g. Newton’s law of gravitation).
A description of nature that en-
compasses more than one law but
has not achieved the uncontrovert-
ible status of a law is sometimes
called a theory. Theories are often
both eponymous and descriptive of
the subject matter (e.g. Einstein’s
theory of relativity and Darwin’s
theory of evolution).
A hypothesisis a theory or law that
retains the suggestion that it may not
be universally true. However, some
hypotheses about which no doubt
still lingers have remained hypothe-
ses (e.g. Avogadro’s hypothesis), for
no clear reason. Clearly there is a de-319 laws, theories, and hypotheses
l