observable at the Surface of Wine. 333 



tablet place a drop of turpentine or spirits of wine, &c., then 

 slide over it the thin glass cover, but do not compress the fluid 

 very much ; the microscope being placed in the vertical po- 

 sition, and provided with a magnifying power from 40 to 100 

 diameters, the contents of the cage are to be examined in the 

 same way as if animalcules were contained in it. As the evapo- 

 ration of either of these fluids takes place, numerous currents 

 and vortices will be seen, especially if a small quantity of finely- 

 powdered coal be ground into them ; the particles of coal being 

 very light, are held in suspension whilst the evaporation is going 

 on, and are whirled about by the currents in different directions." 

 The following fluids Mr. Varley has given as the best for the 

 illustration of the cuiTcnts : — 



" 1. A drop of spirits of vpine, or of naphtha, exhibits two, 

 three, or four vortices or centres of circulation, according to the 

 size of the drop ; and if these vortices are viewed laterally, the 

 lines of particles will be seen forming oblique curves from top to 

 bottom of the drop. 



" 2. Oil of tm-jjentine shows a rapid circulation in two conti- 

 nuous spirals, one to the right, the other to the left, around the 

 drop. These meet in the opposite diameter, from which the 

 particles are carried slowly across the diameter to the place of 

 starting, and this continues while there is fluid enough to let it 

 be seen. 



" 3. If, however, the di'op does not exceed one-tenth of an 

 inch in diameter, it presents the appearance of particles conti- 

 nually rising up in the middle, and radiating in gentle curves 

 to the circumference. 



" 4. If the liquid be put into a very small vial, similar motions 

 are perceived, the particles when they have reached the side of 

 the vial going down to rise up afterwards in the centre or 

 axis. 



"5. If a bubble of air be enclosed in the liquid, motions 

 similar to those described in No. 2 are observed in the part im- 

 mediately in contact with the bubble. 



" 6. In a flat drop of new wine laid on the tablet or disc of 

 the aquatic live-box, but not compressed by the cover, the motion 

 was a regular uniform circulation, the particles rising from below 

 at one end of the drop, then passing straight across on the sur- 

 face, and descending at the other end." 



