493] Comparison of A, B, C together, with H *. EXPERIMENTS, 1773 +. 494] Spreading of electricity on surface of glass plates. 4 plates of English glass were cut out of same piece and coated with bits of tinfoil of the same size. One of these plates was covered at different times with thick solution of lac, which ran into heaps in drying, another with transparent varnish which also ran into heaps, another with solution of lac and vermillion which lay smooth, and the other left as it was. They were all done in the end of the summer and suffered to dry in the open air. The spreading of the electricity on their surface was tried in the manner described 1772, p. 22 [Art. 486]. Tu. Oct. 13 [1772]. Th. 63. N. 203. C.-7. D of Nairne, corks closed immediately. G do. in cem. in 3" or 4". Plate with lac closed immediately, sep. again in 3" or 4". Lac and verm. D°, but much more. Transparent varnish same as lacquer. Plate not varnished closed immediately, sep. again in 5" or 6". * [See Art. 658.] [This is the heading of this bundle of the Journal, though many of the dates belong to 1772.] 495] To see whether the machine used for trying Leyden vials* conducted fast. The heavy and light paper cylinders being both hung to conducting wire, and globet turned till heavy ones separated, the light ones closed in 1'. 1" after the others when the conducting wire communicated with machine, and about 1'. 20" when it did not. 496] The plate covered with solut. lac was undone, and that and the plate not varnished were lacquered in Nairne's manner, one with vermillion, the other without. Neither of them were dried after the operation. The old Lac and vermillion and the transparent varnish were dried before fire, heat uncertain. Frid. Oct. 16 [1772]. Th. 63. N. 20. C.-10. The two plates lacquered in Nairne's manner discharged the electricity of the jars presently. Lac and verm. in 1st manner closed in about 10". Sat. Oct. 17 [1772]. The last varnished plates being dried before fire. Th. 65. N. 21. C. – 7. 1st lac and vermil, closed in 2" or 3", did not sep. in 1'. 2 D° closed rather sooner. Transparent closed and sep. again in about 4". Tu. Oct. 19 [1773]. The varnished glasses were baked over stove, the heat being kept for 2 hours at about 170. Wed. Oct. 20 [1773]. Th. 64. N. 22. C. - 5. Lac & verm. closed in about 15′′. Old lac & verm. Do. Transparent in 1 or 2". Do rubbed with cloth, closed and sep. again in 1 or 2". On Wednesday, the varnished plates were baked for above 2 hours, the heat the greatest part of the time about 210, but part of the time rose a little way into the ball. I suppose must be at least 235 or the 240. Fr. Th. 60. N. 22. C. – 5. Transparent closed and sep. again immed. Last lac & verm. closed & sep. again almost immed. 1st Do closed and sep. again in about 2′′. 497] Glasses for exper. on spreading of elect. 9 plates of English glass & 8 of Nuremberg coated with plates of same size. Sun. Oct. 24 [1773] Th. 63. Comm. - 6. N. 211. [Art. 295.] [Of electrical machine. See Arts. 248, 563, 568, 569.] E. 9 closed in about 2". 8 rather sooner. 7 Do. 6 Do. 5 D° 4, 3, 2, 1 D° 1 did not sep. in 1'. N 8 closed and sep. again in less than 2′′ but did not sep. much. 7 closed in 1 or 2" but did not sep. again soon. 6 closed presently and sep. again more than 8. 5, 4, 3, 2, 1 Do but seemed to sep. at first, to sep. more before it began to close, it was pos. after closing. Sun. & Mon. N 1, 2, 3, 4 & 8 were baked with heat from 130 to 200. The tinfoil of the lowest plate was blistered. Sun. Th. 62. Com. - 15. N. 18. E 2, 3, 4, 5 closed in about 2", 2 and 3 sep. again in 30 or 4[0]. E 1 closed not quite so fast. 3". E 9 not baked closed in about 7", 7 & 6 in about 4", & 8 in about The 5 baked Nuremberg immediately separated wide, some without closing first, others with. N 6 closed and sep. almost immediately, 7 closed and sep. almost immed. but did not sep. wide. 5 closed and sep. again in 5′′ or 7′′. N 8 washed with spts of wine did not close so soon as before. N 8 & E 4 were washed with sp wine & a little ros. varnish & then varnished with rosin. Sun. eve. Th. 60. Com. 20. N. 16. E. 4 did not close in l'. N. 3 closed and sep. again immed. N. 8 & E. 4 were then cased in soft cement. The plates N. 1 & E. 3 were varnished with lac varnish, & the plates N. 2 & E. 2 with a mixture of 6 parts of varnish & 1 of vermilion, & afterwards baked for about 5 hours with a heat part of the time up to 200, and most of the time above 150, & N. 3 & E. 5 were varnished in the same manner, and then cased in a cement composed of 14 of rosin to 12 of brick dust. N.B. E. 5 was heated in drying the varnish to a great degree, so as to make it smoke violently. Wed. Nov. 4 [1772]. Th. 59. N. 161. C. - 18. E. 4 closed in about 4". E. 5 in 3" or 4". N. 8 closed and sep. again in 3 or 4". N. 3 seemed to do the same rather sooner. Fr. Nov. 6 [1772], the plates E. 1 and N. 4 were varnished with rosin and the plates E. 2 & N. 2 varnished with a mixture of 4 parts of rosin varnish to 1 of vermilion & afterwards baked. They were a good deal heated both in varnishing and baking, so as to be somewhat blistered. The plates E. 3 & N. 1 were also varnished before then and dried before fire. Sat. Nov. 7 [1772]. N. 5 and E. 8 were varnished with rosin, and N. 6 and E. 6 varnished with 8 parts of solut. rosin & 3 of vermilion, and then baked for about 2 hours with heat which part of the time rose to 146, but commonly did not exceed 130. Sun. Nov. 7 [1773*]. Th. 63. Com. - 2. N. 3 closed and sep. wide immed. N. 8 closed & sep. again in 2′′ or 3′′. N. 6 rather slower. N. 5 closed and sep. wide immed. N. 4 more so. N. 2 D. N. 1 D. E. 6 closed in 3 or 4". N. 221. E. 8 closed and sep. again in 2 or 3" about 1 inch. 4, 2, 1 rosin and verm. 1st frosin alone, 2 1st Th. Nov. 4 soft cement E 6 rosin and verm. last done 5 hard cem. 8 rosin last done 1 rosin alone 2 & 3 ros. and verm. 1st ros. alone 1st 4.21 of the lac varnish contains 12 gra. of lac. Th. 58. Com. - 13. N. 19. N. 8 in soft cem. closed almost immed. sep. again in 3 or 4". E. 8 in ros. closed and sep. again almost immed. E. 6 ros. and verm. closed and sep. wide immed. N. 5 ros. more so. N. 6 ros. & verm. same as E. 6. Th. Nov. Th. 58. Com. 7. N. 21. E. 4 at first approached a little nearer, afterwards did not. N. 8 closed and sep. again in about 3". E. 2 Lac and verm. closed and sep. wide immed, E. 3 Lac. not so soon. N. 2 Lac and verm. rather quicker. N. 1 Lac. Do. E. 1 not varn. closed in about 8". N. 4 closed and sep. again in about 2". 499] Sat. Nov. E. 8 & N. 5 were varnished with ros. & E. 6 & N. 6 were varnished with 8 parts of solut. rosin & 3 of vermillion. They were afterwards baked over boiling water for about 2 hours, the heat between 115 & 120. Sun. Nov. E. 1 & N. 4 were varnished with 6·0 of thick solut. lac, 3.3 of verm. & 19 of spts, and E. 2 & N. 1 were varnished with 60 of solut. lac, 4·16 of verm. & 9 of sp. last mixture spread on the glasses was 8.0. Mon. Nov. 16 [1772]. Th. 52. The quantity of this N. 2 not covered, closed rather sooner and sep. rather more than Two trial plates were made with two plates of glass with rosin between, for comparing thick rosin with the double plates A and B. Two trial plates were also made on a piece of the white plate glass for comparing N and thin white with D + E. * [See Arts. 370, 371.] |