By J. C. HOADLEY.


The following description of the apparatus used for the determination
of high temperatures, up nearly to the melting point of platinum, is
offered in answer to several inquiries on the subject:

The object to be attained is a convenient and reasonably accurate
application of the method of mixtures to the determination of
temperatures above the range of mercurial thermometers, say 500 deg. F., up
to any point not above the melting point of the most refractory metal
available for the purpose, platinum.

A first requisite is a cup or vessel of convenient form, capable of
holding a suitable quantity of water, say about two pounds avoirdupois.
Berthelot decidedly prefers a simple can of platinum, very thin, with a
light cover of the same metal, to be fastened on by a bayonet hitch. For
strictly laboratory work this may be the best form; but for the hasty
manipulation and rough usage of practical boiler testing something more
robust, but, if possible, equally sensitive, is required. The vessel I
have used is represented in section in the accompanying cut, Fig. 1.

The inner cell, or true containing vessel, is 4.25 inches in diameter;
and of the same height on the side, with a bottom in the form of a
spherical segment, of 4.25 inches radius. It is formed of sheet brass
0.01 inch thick, nickel-plated and polished outside and inside. The
outer case is 8 inches diameter and 8.5 inches deep, of 16-ounce copper,
nickel-plated and polished inside, but plain outside. There are two
handles on opposite sides, for convenience of rapid manipulation. The