A system of physical chemistry - Index of

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A system of physical chemistry - Index of

42 .'/ SYSTEM OF PHYSICAL CHEMISTRY

By way of illustration a few of Paschen's results may be quoted.

The extent of the spectrum examined was from i to 8-8yu, {i.e. the

infra-red region), measurements being carried out by means of the

bolometer. Using a fluorite prism (which is more transparent than

quartz) successive parts of the spectrum could be isolated. The

radiating body consisted of a hollow vessel or cylinder, electrically

heated to any desired temperature, the cylinder being either of platinum

or porcelain with or without a coating of copper oxide. In the

following table / denotes the magnitude of the swing of the galvanometer

needle, a certain swing corresponding to a certain amount of

energy communicated by the radiation to the bolometer. After calibrating

the apparatus, Planck's formula can be used to calculate values

of ; for different wave regions, and these may be compared with experiment.

Table I.—\ = 1-0959 ^.

Width of spectrum isolated = 3'.

Temperature of surroundings = 9'8° C.

T = Temperature of Radiator =

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