0.—2

70

At the adjoining Ralph's Colliery a disastrous explosion occurred during 1914 (when naked lights were in use), originating from gas from a blower in an old standing pillar area. A few days after the explosion I measured an accumulation of 350,000 cubic feet of explosive mixture, and took several samples in duplicate therefrom, using an electric safety-lamp for a Light. The richest sample contained—.Methane, 48'1 per cent.; oxygen, 10'10 per cent. At, Kaitangata No. I Colliery, in the Otago Provincial District, tire-damp was detected by safety-lamp and reported by examining officials on forty-four days during 1916, the largest quantity found at one place being 250 cubic feet of gaseous mixture. With falling barometer there occurs an efflux of gas from goaf; there is also apparent liberation of occluded gas at the coal-faces. Bord and pillar on the panel system is here adopted. During 1879, when naked lights were in use, a disastrous explosion occurred at this colliery by reason of a naked light being carried into unexamined old workings, as at Ralph's during 1914, before mentioned. _ The brown coal mined in the Waikato and Kaitangata districts has the following composition : — Taupiri Kaitangata Extended. No. 1. Fixed carbon ... ... ... ... ... 44'23 38'00 Hydrocarbon ... ... ... ... ... 41'07 39-90 Water ... ... ... ... ... ... 13-14 18-22 Ash ... ... ... ... ... ... 1-56 3'82 Sulphur, per cent. ... ... ... ... ... 0'32 5'40 The quantity of air circulating was measured by me by means of two new anemometers of Biram-Davis type; the temperature was taken with the Davis miners' hygrometer. The analyses of mine-air are by J. S. Maclaurin, D.Sc, F.C.H., Dominion Analyst.' In these investigations 1 received valuable assistance from Inspectors Boyd Bennie ami E. 'li. Green in their respective districts.

Analyses of Ventilation and of Mine-air.

•Name of Colliery and of Ventilating Distriot. I ' A I r n I 1) r IV vmin-iTT\ -n i-v /"I *-*■■- w ■!■ ■ ■— - Quantity of Number of Q , u . 1 ?.'' ty In Degrees I 1 . Analysis of Boturn Air. Air Persons ptJJ-J, _ circulating in ° on Minute. UiStllCt ' MiLtc.. ™ CII 4 . CO, Oxyge CO 2 . Oxygen. Tacpiri Extended Colliery. (28/2/17, between 9 a.m. and 3 p.m.) North side, No. 5 lovol east (tail-rope soction) North side, No. 5 level west Iacpiri Extended Colliery. (28/2/17, between 9 a.m. and 3 p.m.) h side, No. 5 lovol east (tail-rope section h side, No. 5 level wost U ,,:,!.. AT,, tx 1 1 j. Por Per Cub. Ft. Cub. Ft. Deg. Deg. Per Cent. Cent. Cent i) 11,328 41 276 67-5 68*5 0'02 0'10 20'7 8,096 14 578 66 67 loss than 0'08 20'8 0-02 Cub. Ft. 11,328 8,096 Per Cent. 0-10 0-08 Per Cent. 20-73 20-82 41 14 North side, No. 6 level east North side, No. 6 dip west .h side, No. 6 level east .li side, No. 6 dip west t side, No. 4 dip t sido, No. 4 level 3,502 10 350 68 69 5,971 43 139 69 70 less than 0'10 20'7 0-02 16,308 ' 45 . 362 68 69 Ditto 0'10 20'8 9,243 36 229 70 71 „ 0'05 20-8 3.502 5,971 10 43 o-io 20-75 West side, No. 4 dip Wost side, No. 4 level 16,308 i 9,243 45 36 o-io 0-05 20-80 20-86 Total effective in all ventilating districts Scaling and leakage .1 ollooti vo in all ventilating districts nxr anil lpn.lcn.o-r> 54,448 .. .. ..- QO QfCO CtA 54,448 32,852 I 24 ng anu leakage 32,852 24 Main return at upcast shaft Remarks. —Barometer, 30'10", rising. Thermomotor in shade at surface, 4 p.m. : Wet bulb, 60-5"; dry bulb, 69°. Sirocco fan. Watergauge, 1-2". R.P.M. 280. r return at upcast shaft 87,300 .. .. 69 69-5 .. 009 20-6 87,300 0-09 20-04 Kaitanqata No. 1 Colliery. (16/1/17, 9 a.m. to noon.) Main-seam district | 0-18 1 0-20 I 0-44 I 0-40 0-28 0-30 0-22 0-22 20-68 20-64 20-50 20-53 5,906 j 6 984 Extension district 5,751 13 442 No. 6 and Mundy's distriot 11,521 31 (and 2 horses) 332 Total effective in all ventilating districts Sealing and leakage 23,178 9,309 20 (and 9 horses) 195 Main return at upcast shaft 32,487 f 0-43 1 0-40 0-30 0-32 20-46 20-48 Remarks.— Barometer, 30'25",steady. Sirocco fan. Water-gauge, P3". Kaitangata No. 2 Colliery. (17/1/17, 9 a.m. to noon.) Main-workings district Six-foot-seam district 8,679 3,040 32 5 (and 1 horse) 271 488 Total effoctivo in all ventilating districts Scaling and leakage 11,719 5,451 8 (and 2 horses) 531 Main return at fan drift Remarks. —Barometer, 29-84", falling. Sirocco fan. Heating of coal-seam in evidence. 17,170 j 0-22 1 0-25 0-48 0-48 20-17 20-09 * Where horses were employed, a deduction of (JOU cubic feet rro leen computed. r horse por rinute has leell iiihi le befon tho miani ;ity per lurson has