~& 
ON THE ELECTRICAL RESISTANCE OF INSULATING MATERIALS. 689 
TasiEe I.—G@utta-percha-covered Wire. 
a Coil 13. Coil 18. 
——E—E——E—E—————EE———EEEE 
iy AR ‘ AR : AR R. AR 
1 min.| 151.AP. in.| 192. AP. in.| 145.AP.|3 min. | 179. AP. 
millions. illions. illions. millions. 
00034 00031 | 1 0-0083 ee 00084 
0:0047 0:0033 0:0034 975 0:0038 
0:0028 0:0040 0:0029 320 0:0034 
0:0036 0:0037 0:0036 357 0:0038 
Remarks.—* The cable had been put to earth for a considerable time before these 
measurements were made, and was put to earth for 15 min. after each 3 min. test. 
Taste II.—Gutta-percha-covered Wire (No. 22). 
Pressure 1 minute. 4 minutes. 9 minutes. 14 minutes. 19 minutes. 
Se a a ae (Ak Mea leeks Fae 
spheres. A A AR A AR 
P. R. | o37ap.| B® | opzap.| B® | aziap.| FB | sapap.| F | apaap 
" millions. millions. millions. millions. millions. 
0" | 287 | 0.0026 | 293 | 00031 | 221 | oo0se | 242 | o-0032 | 354 | 0.0037 
75 | 283 | % 362 | 90081 | 41y 434 | 452 
00044 0-0051 0:0047 00047 00048 
150 |.362 | 2 474 | % 597 | 0 557 | 2 579 
00042 0:0089 0:0053 0:0055 0-0065 
225 | 436 | 0.0047 | 59 | 0.0065 | 9 | 0.0026 | 722 | o-0os4 | 72 | 0.0084 
300 | 519 | 90047 | 701 724 789 84] 
eee | sed | | ssa | et Py gre Ve 
ot | 242 | 805 346 | — | 366 366 | — 
Remarks.—* Between each series of observations the cable was put to earth for 
two hours. + Immediately after pressure. { Three hours after pressure. 
Tasie II].—Gutta-percha-covered Wire (No. 22). 
Pressure AR 
. in atmo- | Resistance. 
a. spheres. R. 381 AP. ee 
Ps 
hm millions. 
Ciel’, 0 380 0-0038 Current had been kept on the cable 
7 6 75 490 half-an-hour to complete the elec- 
7 9 0 402 0-00. 49 trification previous to taking the 
7 20 150 642 first reading, and was not inter- 
: eS ote 415 0 00. 44 | rupted during the series. 
790 
7 31 0 429 aN 
289) 800% [°° ag? 1000082 
7 42 0 429 sas 
10 0 0 381 Te 
1863. 2Qy 
