_Apparatus._ Flat box, F B (Nos. 40, 41); sheet of glass, G (No. 38); electrophorus (Exp. 68). The two parts of F B are used for the conductors of the condenser (Fig. 54) for the sake of lightness. The bottoms should be next to the glass, which is used for the dielectric on account of its stiffness. The lower tin should rest upon the table. The glass should be perfectly clean and dry (hot). =189. Directions.= (A) Charge the condenser with 15 or 20 good sparks from E C. (B) Lift the condenser by one corner of G (Fig. 54), being careful not to discharge it. Explain why the lower conductor follows the glass. [Illustration: Fig. 54.] =EXPERIMENT 88.= =190. Directions.= (A) Charge and lift the condenser as just explained (Exp. 87). Fig. 54. (B) With your right hand touch the upper tin alone, then the lower tin alone. (C) Touch both tins at the same time, and note the action of the lower one. _=191. Discussion.=_ This clearly shows how strongly the two electrifications are _bound_ in the condenser. Each refuses to escape to the earth, but they instantly rush together at the first opportunity. The dielectric may be shattered in a very heavily-charged condenser by this strong attraction. [Illustration: Fig. 55.] =EXPERIMENT 89. To show how the condenser maybe slowly discharged.= _Apparatus._ Fig. 55. The condenser (Exp. 83); the carbon electroscope with support (Exp. 58); the electrophorus (Exp. 68). =192. Directions.= (A) Charge the condenser by means of the electrophorus; then hang the carbon so that it can swing between the upper conductor and E C placed as shown. _=193. The Electric Chime.=_ The charging and discharging of the carbon being rapid, it acts like a _chime_ as it taps against the tins. =EXPERIMENT 90. To ascertain the location of the charge in the condenser.= _Apparatus._ The condenser, consisting of flat box, F B (Nos. 40, 41); ebonite sheet, E S (No. 27); insulating table, I T (Exp. 64); (when charging, arrange as in Fig. 52.); the electrophorus; hairpin discharger, H P D (No. 48). =194. Directions.= (A) Charge the condenser with 15 or 20 good sparks from E C. (B) Lift I T away from E S by its insulating handle, and set it upon the table. (It may be necessary to hold E S down.) (C) Lift E S directly up and away from F B. (Lift by 2 corners; do not scrape E S along on F B; do not allow E S to touch your clothing.) (D) Replace E S and then I T by its handle quickly, making the condenser complete again. (E) With H P D see if the condenser still holds a charge. Touch F B first (Exp. 86).