422 THE FIGUEES OF EQUILIBRIIBI OF A LIQUID MASS 



exhibit themselves .in the most brilliant colors, and wbicli, notwithstanding 

 their extreme fragilitj, endure for so long a time. They are experiments, too, 

 which may be executed promptly and in the most commodious manner. Here 

 we have not the embarrassments which, in experiments with full masses of oil, 

 result from the equalization of the two densities, from variations of temperature 

 and from the mutual chemical action, however slight, of the two liquids. Still, 

 there are certain experiments which indispensably I'equire the employment of 

 oil and the alcoholic liquid. Such are those of my first series ; such too is 

 that for the realization of the figure generated by an entire node of the meridian 

 line of the nodoid, (4th series, § 27,) &c. 



When a series of experime'nts with the glyceric liquid is terminated, the 

 rings or disks should be washed by agitating them in rain-water ; to dry them, 

 the former are placed on filtering paper and the latter wiped. Two useful pre- 

 cautions may also be prescribed. When a considerable number of experiments 

 are conducted in succession, it is well, from time to time, to remoisten the upper 

 ring ; it will be also proper sometimes to take a new pipe ; when the same one 

 has been used too frequently, the films seem less persistent, doubtless because a 

 small portion of watery vapor introduced by the breath is condensed on the 

 inner edge of the bowl of the pipe. 



§ 17. It has been already remarked that, in these experiments, the disunion 

 of the laminar canteuoid is preceded by the formation of a thread, which is 

 converted into spherules ; now the same is the case in the disunion of all the 

 other laminar figures, just as in that of all the full figures of oil, (2d series, § 62.) 

 If, after having realized a constricted or a dilated unduloid, we continue to raise 

 the upper ring until rupture of equilibrium occurs, we shall see, at the instant 

 of disunion, a spherule some millimetres in diameter escape from the figure and 

 float in the air of the apartment or fall on the bubble which has formed in the 

 lower ring, according to the greater or less tenuity of the film which constitutes 

 the spherule. I shall discuss, in another series, the theory of the production of 

 these threads, whether full or laminar. 



§ 18. We also easily realize, and still by means of the glyceric liquid, the 

 laminar systems which I obtained with oil, in the interior of the alcoholic 

 liquid, while using polyhedral frames of iron Avire, (2d series, §§31 and 35). 

 For this, it is sufficient to plunge one of these frames into a vessel filled with 

 the liquid in question, and, having left it therein for some seconds that it may 

 be thoroughly wetted, withdraw it ; it will be found to be occupied by the 

 laminar system, and always in a complete state — that is, including no inspissated 

 portions appreciable by the sight. It is to this process that I allude at the end 

 of § 35 of the 2d series. The frames, like the rings and disks, must be once 

 treated with diluted nitric acid, (§ 14). 



In order to observe conveniently, and without causing agitation, any one of 

 the laminar systems thus produced, the frame containing it should be placed on 

 Fig. 6 a small structure of iron wire like that which is represented in 

 perspective at figure 6 ; the structures which I use are four centi- 

 metres in width, twelve in length, and two and a half in height. 

 After each series of experiments the frames should be washed 

 by passing them through rain-water, and be left to dry on filter 

 ing paper. 



The perfection of the laminar systems realized by the present process admits 

 of the verification of a peculiarity which had escaped me when I obtained 

 them with oil in the alcoholic liquid : it was perceived that several of the films 

 which had then appeared plane have in reality slight curvatures. On the other 

 hand, the laminar system of the octahedron, which, with oil, was formed of 



