ON THE SO-CALLED VESICULAR VAPOURS OF WATER, ETC. 
29 
Q.QOimm an d 0‘003 mm . Essence of turpentine is still better adapted than the 
balsam for retaining the globules suspended in the air, as in fogs, &c. When, after 
having been cooled below the common temperature, it is breathed upon, a whitish 
precipitate of a streaky appearance is formed like an insoluble salt, which slowly 
descends to the bottom of the vessel, where it coalesces into larger globules*. This 
is also the case with water-globules condensed in this way from the air, which form 
a cloudy precipitate intercepting the passage of light. On being preserved in a bottle 
this cloud will still remain after the lapse of a couple of days, when the water will 
be found at the bottom of the vessel in a globular shape like metallic mercury, without 
adhering to the sides of the glass. By means of this permanent cloud, we might be 
enabled to perform a series of experiments of great interest to meteorology. In this 
way we might determine the influence of water-globules of various sizes in the pas- 
sage of luminous, thermic, and chemical rays. 
Copaiva balsam, upon being breathed upon, becomes coated with a milky film, 
which, to the naked eye, assumes a reticulated appearance after a few moments, 
which is caused by the disappearance of the film sooner at some points than at others. 
Under the microscope the uniform film is decomposed into minute globules, which 
occupy the space of mere points under the strongest magnifying power. They dis- 
appear very rapidly by agglomerating and forming larger globules. This process of 
agglomeration commences simultaneously on the surface of the liquid at a variety 
of different points. From these it proceeds to form circular areas, which continue to 
extend until their line of demarcation consists of merely a single row of globules, 
which also in their turn contract and coalesce into small groups of about a dozen sepa- 
rate spherules. At this time the process of fusion ceases, and the globules are seen 
suddenly to fly apart in virtue of some molecular repulsion, and then gradually dis- 
appear. With boiling water the like phenomena are produced, except that the glo- 
bules are all much larger. In fig. 5 are seen these actions in all their different stages. 
Oil of peppermint condenses moisture which presents phenomena very similar to 
those of copaiva balsam. If the breath be passed through a narrow tube, a system 
of rays is produced, composed of separate globules, which remind one of the form of 
some of the species of Asterias which radiate from a centre, and are likewise com- 
posed of a multitude of separate globular pieces. The irisated colours formed on this 
oil are very brilliant, but soon disappear unless the current of air is constantly kept 
up. The particles of water which give rise to these colours, disappear by immersion 
into the oil, as well as with all the other oils which are susceptible of presenting 
them. The oils of anethum, carrawayand cajeput, also present very similar appear- 
ances. 
* A bottle containing condensed water-globules and essence of turpentine, exposed night and day in a 
northern aspect, became coated at its inner surface on the north side with condensed moisture, and around 
this with transparent acicular crystals arranged in zones around the moisture. The crystals were not obtained 
in sufficient quantity to admit of their being analysed. 
