I N D U S T R I A L A N D ENGINEERING CHEMISTRY
570
Vol. 20, No. 6
Table VI- Carbon Monoxide per Car-Mile in Corresponding Sections of Holland Tunnel, November 13 and 14, 1927, Compared with T h a t Calculated from Road Tests South Tunnel Grade, per cent North Tunnel Grade, per cent
s-1
-3.85, -2.50 N-8 -4.03
South Tunnel, cu. ft. per car-mile North Tunnel, cu. ft. per car-mile Computed from road tests, cu. ft. per car-mile Grade, per cent
2.5 2.3
South Tunnel, cu. ft. per car-mile North Tunnel, cu. ft. per car-mile Computed from road tests, cu. ft. per car-mile Grade, per cent
3.5 2.8
s-2 s-3 s-4 -3.00 -0.25 N-7 N-6 N-5 -4.03 -4.03, $ 0 . 2 5 November 13, 1927 2.9 5.0 2.8 5.2 2.8 -3 November 14, 1927 3.5 6.3 4.3 6.7 3.2 -3
..
.. ..
....
s-5 -0.25, $ 3 . 4 8 N-4 t-0.25 5.0 4.2 4.0 0 6.0 5.5 4.6 0
5-6 4-3.48 N-3 $3.00
....
4.5
.... 6.0
5-7
+3.48 N-2 $3.00
5-8
$3.48 N-1 $2.10, + 2 . 9 0
6.3 5.5 5.1 $3
6.4 5.6
8.3 7.5 5.9
9.3 9.4
$8
with the 3.0 per cent grade used in the early tests. However, flow of water and the electric heaters are functioning properly; difference in operating speed may account for much of the (5) to adjust the dry-cell potentials a t the recording potendiscrepancy, for traffic was not crowded during November tiometers against the standard cells; (6) to supply ink to the 14; the total traffic was only about one-third that of the recording pen; (7) to insert record paper when needed; previous day, stoppages were of no importance, and the (8) to oil the mechanisms of the recording potentiometers; maximum speed of 30 miles per hour was the rule in most and (9) to care for them and make such adjustments as may instances. This speed proves for most cars less economical be desirable from time to time. These operations constitute in gasoline with resulting larger quantity of carbon monoxide a daily routine and in an 8-hour day permit for one man than that calculated from the road tests made at 15 miles only about 1/2-hourJs attention to each recorder, because they are distributed in four stations requiring about a 2-mile per hour. TOTALCOMBUSTIBLEGASES EvoLvED-According to journey to make the rounds. However, the chemist is usually able to attend to these Table 1V the total carbon monoxide evolved in the Holland Tunnel on November 13, 1927, amounts to 366,000 cubic duties in less time and thereafter to do other work in the feet, assuming that the quantity undetermined for section chemical laboratory or check calibrations of the cells while S-6 is the same as in the corresponding section N-3. As they are operating in the recorders. The checking is done hydrogen averages about 0.4 of the carbon monoxide and by allowing a recorder to draw pure outdoor air and passing methane (or equivalent in higher hydrocarbons) about 0.2, into the air stream measured small streams of pure carbon there were also liberated in the exhaust gas 150,000 cubic monoxide from a portable accessory apparatus. If deterifeet of hydrogen and 73,000 cubic feet of methane, totaling oration is considerable, a fresh cell, calibrated in the chemical about 590,000 cubic feet of combustible gas (366,000 150,000 laboratory, is substituted for the failing one. The chemical laboratory is equipped with special apparatus 73,000). This, if it could be separated and collected, is enough to supply for the day, say one thousand families with for calibrating cells. The chemist refills with fresh catalyst the cells that have shown deterioration (by the end of 1927 the gas they would consume in their homes. On November 14 the evolution of combustible gas de- no refills had been necessary), determines their “best rate” creased, but it is estimated a t 172,000 cubic feet of carbon of air flow (flow developing highest potentials), and calibrates monoxide, 69,000 cubic feet of hydrogen, and 34,000 cubic them a t the “best rate” for potentials against air containing feet of methane-a total of 275,000 cubic feet of combustible accurately made low concentrations of carbon monoxide.s Aside from these duties in connection with the recorders, the gas. chemist cooperates with the medical staff by determining Care of Carbon Monoxide Recorders and Duties of Chemist carbon monoxide in blood samples12 taken from tunnel emEach of the 14 carbon monoxide recorders requires the ployees who have had unusual exposures to the tunnel atmosattention of a chemist or an assistant once a day. This is phere. He also consults with other members of the tunnel (1) to change the sulfuric acid if the volume has doubled due staff on special chemical problems, studies the records of to water abstracted from the air stream; (2) to oil the air carbon monoxide, and engages in research pertaining thereto pump and motor machinery and care for it; (3) to adjust the as problems are proposed. 12 Sayers and Yant, U.S. Bur. Mines, Tech. Pafier 918 (1925). air flow in case a change has occurred; (4) to observe that the
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+
Apparatus for Determining Melting Points1 S. Avery THEUNIVERSITY
OF
NEBRASKA, LINCOLN, NBBR.
T H E well-known Thiele tube has been found by Dennis*
to give less accurate results than the Thiele-Dennis tube, which permits of freer circulation and maintains in all parts a more evenly heated liquid. There must be, however, measurable variations of temperature in the different sections of a tube containing a liquid circulating by gravity. To overcome this difficulty the writer has used an apparatus of the following description: The tube is essentially a Thiele tube, lengthened for the use of an Anschutz total-immersion thermometer and modified to permit mechanical circulation by means of a propeller. The 1
2
Received May 14, 1928. J. IND. END.CHBM.,12, 366 (1920).
fluid is liquid petrolatum or glycerol. If sulfuric acid is to be used, the propeller and shaft should be of glass and the bearing in which the shaft turns should be of lead. The propeller may be constructed with arms, or in the form of a spiral. The bearingshould fit the t u b e f a i r l y closely. The shaft is driven by a small fan motor at about half the motor’s maximum speed. The tube is heated in the same manner as the Thiele tube, but less care is required than in an a p p a r a t u s depending upon g r a v i t y for circulation. The temperature of the liquid can be regulated with great precision. The tendency of the thermometer to fluctuate, when the tube is heated slowly, is avoided.
$I
