70 Notices respecting New Books. 
the hope of future evidence demonstrating its truth—a mode 
of procedure which always tends to enfeeble the mind and 
to induce improper acquiescence in the mere dicta of au- 
thority, without exercising the judgement. 
The classification followed by Mr. Murray is the follow- 
ing:—Part I. Of the general forces productive of chemical 
phenomena— attraction of aggregation —chemical at- 
traction or affinity; of repulsion, and the powers by which 
it is produced—caloric—light—electricity and Gaivanism. 
Part If. Of the chemical properties and relations of indivi- 
dual substances; of aimospheric air and its principles— 
oxygen—nitrogen; of water and its base—hydrogen ; of 
alkalis and their bases; of earths and their bases; of acids 
and their bases; of metals; of the native combinations of 
acids; earths, metals, and inflammables—-nineral com- 
pounds; of vegetable compounds ; of animal compounds. 
We cannot but think that in the present state of the 
science of chemistry, the alkalis and the earths should have 
been classed with the metals; but perhaps the author was 
afraid of being thought an innovator. His work, however, 
presents all the modern discoveries, detailed with consider- 
able precision and perspicuity.—As a specimen of the au- 
thor’s style, we extract what he says 
© Of the Radiation of Caloric. 
<¢ Besides the caloric, which a body in cooling communi- 
cates to the matter with which it is in contact, a portion is 
thrown from its surface in right lines moving with great 
velocity, capable of being rendered sensible at a_consider- 
able distance, and obeying the same laws of motion as the 
rays of light. This forms the radiation of caloric. It was 
observed more than a century ago, by Mariotte, and also 
by Lambert; and within a later period it has been inyesti- 
gated hy Scheele, Saussure, and Pictet, Herschel, and Leslie. 
¢ Vhe experiment in which this.rqdiation of caloric is best 
displayed, consists in placing a hot body, as a heated ball 
of iron, in the focus of a concave metallic mirror, opposite 
to which, at the distance of 10 or 12 feet, is placed a simi- 
lar mirror, haying the ball of an air thermometer in its 
focus*. The moment the hot body ts introduced, the op- 
posite thermometer indicates elevation of temperature, the 
air in its ball being expanded, and pressing on the liquid so 
* The differential air thermometer is well adapted to show these effects, and 
£0 allow all the facts with regard to the radiation of caloric to be determined 
with much accuracy, It was applied to this purpose by Mr. Leslie. 
as 
