Miscellanies. | 185 
CHEMISTRY. 
1, New Experiments in Caloric, by MM. Nox and Met- 
Loni, performed by means of the Thermo-multiplier. (Translated 
and abridged from the Annales de Chim. et de Phys. Oct, 1831, 
by C. U. Shepard.)—The Thermo-multiplier is a species of 
moscope, which is so delicate an indicator of temperature, as to be 
sensibly affected by the natural heat of a person, placed at the dis- 
tance of twenty-five or thirty feet.. The principal parts of the in- 
strument are: Ist, a thermo-electric pile; 2ndly, a galvanometer 
with two needles, which are specially designed for the thermo-electric 
currents. It is the first part of this apparatus which constitutes it a— 
thermoscopic instrument; the second serves simply as an index. 
The heat excites the electric currents in the pile; these currents 
pass through two metallic wires which connect the two kinds of ap- 
paratus together, are transmitted to the galvanometer, and act through 
their influence upon the steel needle, by causing it to turn round 
from its natural position of equilibrium with a force more or signe stri- 
king, according to the intensity of the calorific emanation. 3 
Heat radiates freely through the atmosphere ; it traverses Pee 
der the radiant form, glass and rock crystal. This would induce us 
to imagine, that the instantaneous passage of the rays of heat through 
bodies, depends upon the same circumstances which allow of their 
permeability by the rays of light ; or, in other words, that the instan- 
taneous passage of radiant heat through bodies, depends upon the 
degree of their transparency. ‘This in fact, is what generally hap- 
pens; for the heating rays traverse with more or less facility, selenite, 
mica, oil, alcohol, and nitric acid. Of this we assured ourselves by 
the following experiment. Lamina, or strata of these different sub- 
Stances, were placed successively at the extremity of the cylindrical 
appendix, whose axis was vertical and superior to the reflector. At 
@ certain distance above it, a ball of iron, heated either in live coals 
or boiling water, was rapidly passed ; and at the same instant, the steel 
needle was seen to deviate more or less from its position in equilibrio. 
But if the general law of the rapid movement of the caloric through 
the transparent substances above mentioned, is thus established, it is 
altogether the reverse as respects the most useful and the most wide-— 
ly diffused liquid in nature, Water intercepts the — 
“Passage of the calorific rays: it intercepts . them entirely 5 
obstacle which it opposes to them is so-insurmountable; fhe 
Vou. XXII1.—No. 1. 24 
