Mr . de Luc 
418 
subject to anomalies from various causes, among which are 
the following. If the water that evaporates is warmer than 
the space which receives the steam, more moisture is produced 
in that space, or the quantity of steam is greater in it than 
by an equal temperature in both ; and vice versa. More or 
less distance of the part of the space where the hygrometer 
stands from the sides of the vessel, produces also anomalies ; as 
according to their own state of moisture, if near enough, they 
have an influence on moisture in that space, as I have ex- 
plained in my former paper ; and this is often the case In 
some measure when the vessels are too small. Lastly, diffe- 
rences in the temperature of the whole or of some part of the 
vessel, comparatively with that of the space, are the most com- 
mon causes of anomalies ; for steam is alternately decomposed 
and reproduced by those differences, and when they have once 
begun in a vessel, there is no certain means to bring it to a 
regular course of phenomena, except by beginning again, or 
by a long equal temperature. 
I come now to the experiments, in which I shall indicate 
some effects of those causes. 
FIRST EXPERIMENT. 
The receiver used was about eight inches in diameter, and 
twelve in height. One of my hygrometers was suspended in 
it, with a thermometer, the degrees of which were actually 
divided in ten parts. In the evening, a very large wet cloth 
was placed in loose folds on its bottom, and the first ob- 
servation was made the next morning as follows. 
Time. Long Gage. Short Gage. Hygrom. Therm. 
7 h 5' A. M. 0.0 — 9 6 >5 4>7’75 
