96
T H E J O U R N A L OF I N D U S T R I A L AND ENGIiYEERIiVG C H E M I S T R Y .
and submerged in a large tube or jacket through whose removable, but water-tight, cover passes the pipe connecting the cylinder with the high-pressure pump. The jacket is provided with a graduated glass tube like a gauge glass, t o act as a n expansion indicator, and is completely filled with water, after which the level in the glass tube is noted. The test pressure is then applied to the cylinder and the levels noted during and after the application, the water in the jacket being forced into the glass tube as the cylinder expands and receding t o its former level after removal of pressure if there has been no permanent expansion. The other method (Fig. 13) involves the use of the Sturke-Watson-Stillman testing machine and dispenses with a water-jacket. This machine consists essentially of a screw displacement piston which forces enough water into an already filled cylinder t o produce the desired pressure. Attached to the pump cylinder are two graduated glass tubes, one serving as the expansion indicator, the other, back of the stuffing box, as the leakage indicator. The exact delivery of the pump per turn of screw is known and provision made for registering each turn or fraction thereof.
Feb., 1912
noting the new level-if such there is-in the expansion indicator after opening the valve. I n calculating the total expansion, proper allowance must be made for the compressibility of the water in both pump and cylinder and for the volume displaced as indicated on the graduated scale. This method requires more care than the waterjacket method, but when properly conducted is more expeditious and avoids not only the discomforts attendant upon the raising of cylinders from immersion in water but also the necessity of any lifting whatsoever. LABORATORY GENERAL CARBONICCo.. NEW YORKCITY.
THE COMPOSITION OF SOME MINE GASES, AND A DESCRIPTION OF A SIMPLE METHANE APPARATUS.’ By G. A. BURRELL. Received Dec. 15, 1911.
The Bureau of Mines has, in the study it has been making of mine gases, examined samples taken under different conditions, some of which are here presented, also some analytical results obtained in related experimental work. No. 1 SERIES. No. 1 Sample: Incomplete combustion of methane. Original mixture contained 10.03% CHI. 10.16%COz 2 . 13Y0 CO 1.39%Hz Products found after explosion 86.32%?*Tz 0 . 0 0 7 o2 ~ 0.00% CzH, 0.00% C H I
1
1
I
No. 2 Sample: Incomplete combustion of methane. Original mixture contained 10 .9470 CH,. 8.35%boz
Products found after explosion
j 83:::;E
1
I
FIG. 13.
Assuming the cylinder under test to be full of water and all connections between it and the pump free of air, a reading is made of both indicators and the position of the piston accurately noted on the graduated scale provided for that purpose. The expansion indicator is then closed off with a valve, and the hand wheel turned until the desired pressure is attained after which the piston is carefully returned to exactly its original position and the valve to the expansion indicator re-opened. I t is plain that if the cylinder suffered any permanent expansion its water-containing capacity must have . been increased. The extent of this is measured by
. 5 2 % N2
0.00%02 0.00% CzHl 0.00%CH1
In these experiments pure methane was prepared and mixed with air in such proportion t h a t not enough of the latter was present for the complete combustion of the methane. The mixtures were then exploded and the products of combustion examined. The most explosive proportion of methane and air contains 9 . 4 7 per cent. of methane. When the latter is increased above this figure certain products are formed about which there has been some disagreement. Some investigators have gone on record as saying t h a t no carbon monoxide is formed. According to these experiments the carbon monoxide a n d ’ hydrogen increase, and the carbon dioxide decreases as the methane content of the original mixture is raised. Olefine hydrocarbons, acetylene, or unburned methane were not found in the products of combustion. The carbon monoxide and carbon dioxide formed satisfies the carbon originally present 1 Paper read at the December Meeting of the Coal Mining Institute of America by permission of the Director of the U. S. Bureau of Mines.
T H E JOL-RA\-,4L OF Ti\-DT2STRIA.L
Feb., 1912
in the methane. These figures represent the proportions of gases present in the explosion pipette after the combustion. A contraction in volume of course, took place, consequently the proportions are larger than would be found after a mine explosion where mine air from other parts of the mine would rush in t o equalize the pressure. To the carbon monoxide formed in this manner is due some of the carbon monoxide found in the after-damp following mine explosions. Not entirely, however, and in many cases the smaller proportions are formed in this manner, because the incandescent carbon of heated coal dust appears t o be mainly responsible for the production of carbon monoxide found after dust explosions. No. 2 SERIES. Crevice samples obtained after explosives had been fired in coal mines. No. 1 Sample. Per cent. COz.. ................................ 0 2
16.8 4.3
...................................
Hz .................................. N2
8.9 29.9
.................................. No. 2 Sample.
Per cent
co2 .................................
.... co... CH,. .
,
0 2
HZ..................................
. .
N P...................................
9.1 7.5 3.2 14.1 4.1 62.0
No. 2 series of samples show the gases formed by firing blasting explosives in coal mines. Both 'black powder and permissible explosives produce noxiousgases. These samples were taken from the crevices produced b y the breaking down of the coal. The explosive and noxious character of the gases will be observed, and accounts for the fact t h a t the miner is sometimes burned when he innocently puts his lamp to the coal t o examine the effects of his blast. No. 3 SERIES. sample taken immediately after shot A had
No. 1 Sample.-Crevice been fired.
Per cent. CO2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
........................ co ........................ CH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.40
02.
1.40
. . . . 0.74 . . _ _75.70 taken 4 minutes after shot A had been fired. Per cent.
No. 2 Sample.-Sample
COP................................. 02..
co
................................. ....
....
CH .... .... HZ.................................. NZ...................................
No. 3 Sample.-Crevice been fired.
0.56 20.22 0.16 0.71 0.06 78.29
sample taken immediately after shot Per cent.
co*................................. 0 2 .................................
......
..................
.................
2.50 16.91 1.21
€3
had
i4-VD EiVGI,YEERI;VG C H E - M I S T R Y . No. 4 Sample.-Sample
taken 4 minutes after shot B had been fired. Per cent.
CO2 .................................
0.30
. . . . . . . . 20.61
02.
co
97
....
0.02
................................. 0.25 0.01 .......... 7 8 . 8 1
CH Hz .................................. Nz ....
No. 3 series of samples represent further gases obtained after explosives had been fired t o break down coal. The crevice samples were obtained b y proceeding immediately to the face after the shot had been fired and collecting the samples as the gas exuded from the coal crevices. I n each case a wait of 4 minutes was made and then the sampler proceeded t o the face t o collect another sample a t about the place the miner would stand to attend t o his shot. I n one case 0.16 per cent. of carbon monoxide was found a harmful quantity. These explosives were fired under conditions which do not represent best practice. Other experiments are being carried on b y the Bureau t o obtain further data on this subject, so as to determine the causes which lead t o the production of harmful quantities of noxious gases. Work thus far accomplished shows that i t is bad practice to proceed immediately to the face after a shot has been fired. Even those powders which contain within themselves sufficient oxygen for the complete combustion of the carbonaceous matter present in the explosive produced, when fired in coal mines, some carbon monoxide, due again t o reaction with the carbon of the coal dust. Some explosives, however, are themselves very deficient in oxygen. No. 4 SERIES. Combustion of gases from an enclosed area in an anthracite mine. Per cent. Sample hTo. Date. con. ox. CO. CH.. Hz. 14.0 68.8 15 .o 0.0 1 Oct. 31 2.2 0.0 18.1 65 .O 2.3 14.6 2 Nov. 1 3
XOV.
4
Nov. 2 Nov. 3 h-ov. 6
5 6
2
2.6 2.9 2.8 2.6
6.2 5.7 4.1 3 .o
0 .o
0 .o
0.0 0.0
67 . O 62.1 58.2 41.4
24.2 29.3 34.9 53 .O
These gases, series No. 4, show the composition of the atmosphere in an enclosed section of a n anthracite mine. This section of the mine was sealed off because of a fire which existed in an adjoining section. The fire did not affect the particular area from which these samples were obtained because of a heavy intervening roof fall, consequently the gases represent those trapped and given off normally in a stagnant section, except that a stopping was leaking and some air was finding its way into the interior from the ventilating current. The stopping was tightened and the rapid absorption of oxygen by the coal is shown by the third analyses. Four days later the oxygen had dropped t o 3 per cent. Even so, some air was finding access. The rapid accumulation of methane is also shown, 5 3 per cent. on the sixth day. No. 5 SERIES. Composition of gases from an enclosed area in a bituminous mine. Per cent. 7
Sample No. 1
2
Con.
1s o 1.20
02.
co.
0.30 0.30
0.00 0.00
NZ. 5'%' .29 5.37
92.91 93.13
T H E ]OUR.VAL 01; I . V D U S T R l A L AA'D E.\-GIC\'EERIAV.VG C I I E M I S T R Y .
98
Series 5 shows t h e composition of gases from an enclosed area in a bituminous mine. A mine fire had once existed in the area and thesc samples were collected by means of breathing helmets 9 munths after the fire had originated and prior to the rcopening of the mine, The oxygen had almost entirely disappeared. The mine is classed as non-gaseous. An accumulation equal t o over 5 per ccnt. methane bad taken place.
Sample No. COa. 1
8.07
2 3
9.14
2.93
02.
1.69 1.83 10.34
the burning area could not take place. t o be the case.
Sample NO.
1.32 0.36
1.37 1.03 0.13
3.39 3.60 0.82
83.90 83.08 85.22
COS.
1 2 ,on I,.>
