WITHDRAWN FROM THE ACTION OF GRAVITY. 595 



When we wish to use one of these soUd systems of iron, be- 

 fore introducing it into the vessel, it must be completely moist- 

 ened with oil ; and for this purpose it is not sufficient simply to 

 immerse it in this liquid, but it must be carefully rubbed with 

 the finger. The presence of this coating facilitates the adherence 

 of the hquid mass. 



We shall continue to make use of the vessel with plane walls, 

 described in the preceding memoir, § 8*; a common-shaped 

 bottle, and the flask previously mentioned (§ 5 and S) in the 

 same memoir, are not w-ell adapted, because they do not exhibit 

 the true figure of the mass. 



When the solid system is composed of a single piece, it is 

 supported by a vertical iron wire, w-hich is screwed to the lower 

 end of the axis traversing the metallic stopper ; but for certain 

 experiments the solid system is formed of two isolated parts, 

 and then only one of them is attached to the axis, as I have 

 stated ; the other is supported by small feet which rest upon the 

 bottom of the vessel. It need not be mentioned, that those 

 liquids only which are prepared in such a manner as to be inca- 

 pable of exerting any chemical action upon each other, can be 

 employed (§ 6 and 24 of the preceding memoir). 



In addition to the little funnel for introducing the mass of oil 

 into the vessel, the iron wire which serves for uniting the iso- 

 lated spheres, &c., of which I have spoken in the preceding 

 memoir, the experiments require some other accessory instru- 

 ments, as, in the first place, a small glass syringe, the point of 

 which is elongated and slightly bent. It is used as a sucking- 

 difference in the aspect of the two liquids, he dissolved intentionally a little 

 oxide of copper in the oil, so as to render tlve latter of a green colour. The 

 compound having thus heen made heforehand, and rendered perfectly homo- 

 geneous, and the alcoholic mixture having been regulated according to the 

 density of the modified oil, the presence of the copper in solution could not 

 produce any inconvenience ; but in this case also the solid systems should un- 

 questionably he made of iron. 



* In making the experiments relating to the present memoir, I found that 

 it was requisite slightly to modify the apparatus in question. The second per- 

 foration in the plate forming the lid of the vessel should be but little smaller 

 than the central ajierture ; its neck should be less elevated ; and lastly, it should 

 be placed near the other ; if left as previously described and figured, the em- 

 ployment of the acce-^sory instruments which we shall describe would be im- 

 possible. Moreover, the neck of the central aperture should be furnished with 

 a slight rim, so that it may he easily taken hold of when we wish to remove 

 the lid, as e. r/. when it is required to attach a solid system which is too large 

 to pass through this same aperture to the axis which traverses the stopper. 

 Lastly, the vessel should be furnished with a stop-cock at its lower part, so 

 that it may be easily emptied. 



