of the so-called Storm- glass. 97 



crust ; and they gently subside and become heaped up below. A 

 very large storm-glass (which will be described presently) shows 

 this action well. The feathers formed above are not only 

 pushed down by other feathers, but are also detached by a slight 

 tremor or agitation; as also by a rise in temperature, which 

 loosens their hold ; and in descending slowly through the clear 

 liquid they often turn over and settle down on the lower deposit, 

 thus presenting the appearance of having started up from that 

 deposit, which is the general notion. The feathers that turn 

 over often have small lumps of the top crust attached to them, 

 so that the root end, so to speak, is the heavier. The minute 

 stars which circulate between the upper crust and the lower de- 

 posit, which are said to indicate high wind or storm, are simple 

 effects of cooling. During the months of April, May, and June 

 1862, a storm-glass hanging in an east window so as to receive 

 the rays of the rising sun, constantly exhibited these stars moving 

 in currents in the clear space between the two deposits after the 

 sun had left the window. These minute stars are exceedingly 

 beautiful, and consist of four, six, and eight radii, with several 

 anomalous forms. 



The ordinary storm-glass, suspended so as to be near a window- 

 pane, will have its deposits often heaped up on the side near the 

 cold glass, an effect which is most strikingly produced by put- 

 ting the storm-glass mixture into a large white glass bottle in 

 sufficient quantity to fill about two-thirds of it. In an experi- 

 ment of this kind, the mixture was compounded of 20 drachms 

 of camphor, 304 grains of nitre, 304 grains of sal-ammoniac, 

 72 fluid-drachms of distilled water, 96 fluid-drachms of spirits 

 of wine, and 8 drops of oil of camphor. The mixture was gently 

 warmed in an evaporating- dish until it reached 98°; it was then 

 put into a quart white-glass bottle ; and the stopple was tied over, 

 the object being to see the effect of hermetically sealing. 



On comparing this bottle with the storm-glass placed by the 

 side of it, the results were certainly such as to warrant the con- 

 clusion that heat alone is the principle at work. The deposit 

 was invariably heaped up towards the window in the form of an 

 inclined plane, the perpendicular of which coincided with the 

 tangent formed by the cold window-pane and the curve of the 

 bottle; and this perpendicular varied in height from near the 

 surface of the liquid to about halfway down, according as the 

 night was cold or frosty, or the afternoon sun shone upon the 

 window. The film at the top would sometimes be confined 

 entirely to the side nearest the window. A little sunshine by 

 day would clear away this top crust entirely; the cold of night 

 would bring it back, and, if colder than usual, would thicken it 



Phil. Mag. S. 4. Vol. 26. No. 173. Aug. 1863. H 



