*Automatic Drops of other Liquids.*—Liquids which possess a low equi-density temperature with water do not form automatic drops like aniline, as the rate of cooling at the surface is too slow, and hence the floating mass of liquid does not attain a density in excess of that of the water beneath. Aceto-acetic ether, however, behaves like aniline, if the temperature of the water be maintained at about 170° F. (77° C.), but as this liquid is fairly soluble in hot water further quantities must be added during the progress of the experiment. Results equal to those obtained with aniline, however, may be secured by using nitrobenzene in nitric acid of specific gravity 1·2 at 59° F. (15° C.), the acid being heated to 185° F. (85° C.); and here you see the yellow drop performing its alternate ascents and descents exactly as in the case of aniline and water. Other examples might be given; but we may take it as a general rule that when the equi-density temperature of the liquid and medium is above 125° F. (52° C.), the phenomenon of the automatic drop may usually be observed when the temperature is raised by 30° F. (17° C.), above this point. *Liquid Jets.*—So far we have been observing the formation of single drops, growing slowly at the end of a tube, or breaking away from a large mass of the floating liquid. If, however, we accelerate the speed at which the liquid escapes, the drop has no time to form at the outlet, and a jet is then formed. We are all familiar with a jet of water escaping from a tap; it consists of an unbroken column of the liquid up to a certain distance, depending upon the pressure, but the lower part is broken up into a large number of drops, which break away from the column at a definite distance from the tap. There are many remarkable features about jets which I do not intend to discuss here, as it is only intended to consider the manner in which the drops at the end are formed. To observe this procedure, it is necessary again to resort to our method of slowing down the rate of formation, by allowing the liquid to flow into a medium only slightly inferior in density. For this purpose, orthotoluidine falling into water at the ordinary room temperature is eminently satisfactory; and we see on the screen the projection of a pipe, with its end under water, placed so that a jet of orthotoluidine may be discharged vertically downwards from a stoppered funnel. I open the tap slightly at first, and we then merely form a single drop at the end. Now it is opened more widely, and you observe that the drop breaks away some distance below the outlet, being rapidly succeeded by another and another (Fig. 23). On still further opening the tap the drops form at a still greater distance from the end of the pipe, and succeed each other more rapidly, so that quite a number appear in view at any given moment (Figs. 24 and 25). Notice how the drop is distorted by breaking away from the stream of liquid, and how it