itional
means of determination. For example, all the specimens of bornite and
pyrrhotite examined yielded sulphuretted hydrogen with tartaric,
citric, and oxalic acids, but chalcopyrite and pyrite do not. On the
other hand, the use of the organic acids may give rise in some cases to
the formation of nitric acid, which in its nascent condition will
afford a very powerful agent of decomposition. Thus all the sulphides
examined (seventeen), with the exception of molybdenite and cinnabar,
were quickly attacked by citric or tartaric acid, to which a little
potassium nitrate had been added. Potassium chlorate produces a similar
though slower action. These examples are sufficient to show that Dr.
Bolton has found a promising field of inquiry, and, singular to say,
considering the attention which the action of organic acids has
received, it is a field believed to be entirely new. He is continuing
his researches.

SCIENTIFIC ORCHESTRATION.

Prof. Mayer has turned his valuable researches in acoustical science to
aesthetic uses, and criticises the present mode of arranging orchestras,
the defects of which he proves by experiment. He took an old silver
watch, beating four times a second, and caused it to gain thirty
seconds per hour, so that every two minutes its tick coincided with the
tick of an ordinary spring balance American clock, also making four
beats the second. The latter was placed several feet, and the watch two
feet, from the ear. In this position the ticks of the watch were lost
for _nine seconds_, about the time of coincidence. The tick of the
watch disappeared, "with a sharp _chirp_, like a cricket's, and
reappears with a sound like that made by a boy's marble falling upon
others in his pocket." This experiment shows most effectively that one
sonorous impression may overcome and obliterate another, but to do so
it must be more intense and of lower pitch. If of higher pitch, it
cannot neutralize the other sound, however much the first may exceed
the latter in intensity. This discovery, Prof. Mayer thinks, is, "next
after the demonstration of the fact that the ear is capable of
analyzing compound musical sounds into their constituent or partial
simple tones, the most important addition yet made to our knowledge of
hearing." High sounds cannot obliterate low ones, but, on the contrary,
the sensation of each partial tone of which compound musical sounds is
formed is diminished by all the tones below it in pitc