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By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

4. Preliminary Study - Remote Seal Checker 4.1 Introduction Determination of the completeness of each individual seal at the time of its emplacement is essential for an effective remote sealing system. A satisfactory seal checking technique should provide a signal which: (1) indicates percentage completion as the seal is emplaced (2) provides a definite indication of a complete seal (3) indicates the size of the unsealed area if a complete seal is not feasible This information is required to establish the need for additional seal material, the need for additional seals, and the risk likely involved in entering the mine., In many situations it is as important to know the quality of a seal as it is to build an effective one. It is likely that with repeated use the remote sealing technique developed by Foster-Miller Associates will be sufficiently reliable and predictable to preclude the seal checking requirement. It is recommended, however, that each seal be checked during construction to insure its completeness and increase the level of confidence so necessary in reopening the mine. 4.2 Description of General Problem Several characteristics of remote mine seals are important in considering techniques for evaluating the effectiveness of these seals. These include:

Jan 1, 1973

By Victor E. Kral

"INTRODUCTION The Phelps Stokes iron deposit, also known as the Iron Mountain claim, was examined by G. L. Thompson, an engineer of the Bureau of Mines, in January 1943. As a result, the Division of Geophysical Exploration 3/ made a magnetorater survey of the deposit in June 1944, and the Mining Branch included it in a,project to explore Nevada iron deposits.The Bureau explored the deposit from September to November 1944 by means of 643 feet of diamond drilling and 445 feet of trenching holes were drilled, all of which penetrated more than: 100 feet of good-grade magnetite, although nearly all the ore except that found in the first hole contained an excessive amount of sulfur. Trenching was done largely over the first two holes, PS-1 and PS-2, and exposed the full width of the ore.The deposit is in Nye County, Nevada, 7.7 miles east of Gabbs. The property was discovered in 1902 was patented in 1907. There has been no production from the property and except for the Bureau's investigation,,has not been, explored since it was patented.Magnetite is the principal ore mineral; it occurs as fine-grained particles associated with sulfides and cemented with talc and calcite."

Feb 1, 1947

By Richard A. Thomas, Isaac A. Zlochower, Gregory M. Green, Kenneth L. Cashdollar, Martin Hertzberg

This paper reports the results of flammability studies for methane, propane. hydrogen, and deuterium gases in air conducted by the Pittsburgh Research Laboratory. Knowledge of the explosion hazards of these gases is important to the coal mining industry and to other industries that produce or use flammable gases. The experimental research was conducted in 20 L and 120 L closed explosion chambers under both quiescent and turbulent conditions, using both electric spark and pyrotechnic ignition sources. The data reported here generally confirm the data of previous investigators, but they are more comprehensive than those reported previously. The results illustrate the complications associated with buoyancy, turbulence, selective diffusion, and ignitor strength versus chamber size. Although the lower flammable limits (LFLs) are well defined for methane (CH,) and Propane (CA), the LFLs for hydrogen (HZ) and its heavier isotope deuterium (D2) are much more dependent on the limit criterion chosen. A similar behavior is observed for the upper flammable limit of propane. The data presented include lower and upper flammable limits, maximum pressures, and maximum rates of pressure rise. The rates of pressure rise, even when normalized by the cube root of the chamber volume (V 1/3), are shown to be sensitive to chamber size.

By W. E. Young

Iron ore occurs in abundance in Iron and Washington Counties in southwestern Utah. Outcrops are encountered over a wide area extending from Paragonah on the northeast to Bull Valley on the southwest. Outcrops also occur on the Wah Wah Range and on Blue Mountain on the north edge of Iron County. The greater concentration of known deposits occurs in and around the margins of three mountainous uplifts - Iron Mountain, Granite Mountain, and Three Peaks - comprising a belt about 3 miles wide and 23 miles long (fig. 1). This area was partly explored by the Bureau of Mines in cooperation with the Geophysical Division of the Bureau of Mines and the Geological Survey under the strategic minerals program during 1942 to 1945. The exploratory work comprised geological and topographic mapping, geophysical prospecting with a magnetometer, diamond drilling, trenching and test pitting, sampling ore exposures and old workings, and constructing and repairing roads. The Pinto-Iron Springs district is the most important known source of iron ore for the steel plants of the West. The future economic status of the Intermountain and Pacific coast regions will depend largely upon the successful development and exploitation of substantial iron-ore bodies in this district.

May 1, 1947

By Edward A. Barrett, Lynn L. Rethi

Recent studies have shown that miners performing construction, maintenance, and repair (CMR) work activities in the conduct of their jobs incur from 39 to 65 percent of all reported injuries in the mining industry, The number is particularly high at surface aggregate operations; however, the problem exists at all mining locations and commodities. To address this issue, an interactive, (3-D) slides training exercise, Hazard Recognition Training Program for Construction. Maintenance and Repair Activities, was developed. The purpose of the exercise is to teach work& to recognize CMR hazards in the workplace and to deal with them using accepted safe work procedures. It was field tested using a total of 340 persons from surface mining operations in six states. The subjects were tested before and after the training intervention to determine if objectives of the instruction were achieved. Results indicated that 7 1 percent of the participants showed improvement in ink test scores. Following the posttest, subjects responded to a seven question Likert scale. These questions related to the validity of the exercise and the utility of the training program. More than 93 percent of the miners reported that they "learned something new from the training" and over 94% said they "would use these practices to work more safely".

By B. P. Martinez

This report presents the results of a research and development program in recovering waste-rolling oils conducted by the Bethlehem Steel Co., before 1954 at its Sparrows Point plant, Sparrow Point, Md., with the cooperation of the Bureau of Mines, U. S. Department of the Interior, College Park, Md. The objective of the program was twofold: First, to recover oil for reuse in the plant; and second, to stop pollution, by oil, of the stream and harbor areas in the immediate vicinity of the plant. The sequence of the investigations was laboratory and pilot plant studies on sedimentation, simple aeration, and flotation for the separation of oil and water; and construction of a production unit using standard flotation equipment. This work was only preliminary for the Bethlehem Steel Co. and it has continued research on this problem. Recent progress indicates that new, improved processes will soon replace the flotation units described in this report. The first efforts to separate oil and water by simple sedimentation were unsuccessful. To establish the cause of this failure, microscope examinations and measurements were made on cold-reduction rolling mill cooling-water effluents containing oil in suspension. It was discovered that an average oil globule, held in suspension, was only 0.001 inch in diameter and would not coagulate with other globules for normal sedimentation at room temperature. The next step in the sequence of studies was to coagulate the oil suspension by simple aeration with air under slight pressure. The aeration methods studied were effective in removing up to 68 percent of the total oil but were approaching flotation in principle. The final investigation of the series was flotation of the oil in conventional laboratory-size flotation cells. The small-bubble method, without reagents, floated up to 89 percent of the total oil held in suspension and was the process selected for pilot-plant development.

Jan 1, 1959

By T. J. Ballard, Austin B. Clayton

"INTRODUCTION The Conrad Hill mine was first opened as a gold mine about 1832 and has been operated at various times since then.The Bureau of Mines, as part of the strategic minerals program, mapped and sampled the accessible mine workings.The: work failed to reveal appreciable copper values or evidence of additional ore deposits.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the and that they make the greatest possible contribution to national security and economy. The Mining Division, Lowell B. Moon, chief, conducts preliminary examinations, does the actual investigative work, and prepares the final report. The Metallurgical Division, Oliver C. Ralston, chief, analyzes samples and makes beneficiation tests.The field work embodied in this report was under the direction of Austin B. Clayton. The final report was prepared by T. J. Ballard uncle,- the general supervision of Mitchell H. Kline, chief, Raleigh, N. C., Branch, Mining Division. Analyses of samples and beneficiation tests were made by the Metallurgical Division. ACCESS AND OWNERSHIPThe property is 6 miles southeast of Lexington, N. C., and can be reached by U. S. Highway 64, turning off at Hedrick Grove Church, and is 1 mile north from the highway on the county road. The mine is in Davidson County at approximately 35° 47' latitude and 80° 10' longitude (fig. 1).The property comprises 471 acres and is owned (1943) by the McKeeMining Co., 512 Fifth Avenue, New York City. The property was optioned to Woodrow McKay of Lexington, N. C., in 1943, who in turn subleased the property to the Robert G. Lassiter interests of Raleigh, N. C."

May 1, 1948

By Robert J. Willard

This chapter includes tables for 1982 that were not available in time for publication of the 1982 Minerals Yearbook, but does not include corresponding tables for 1983. The value of raw nonfuel minerals produced in the United States during 1988 was estimated at $21.1 billion, an increase of $1.5 billion over the value for 1982. This is a reversal of last year's downturn in value from that of 1981, which was the only decrease noted since 1971; hence, an overall trend of increasing values has been maintained for 12 years, except for 1982. Although the reversal is a basis for cautious economic optimism, it is tempered by continued problems in the domestic mining industry: inadequate funds for capital investment and competition with other countries that have lower production costs. Output of metal commodities in 1983 increased for 8 out of 21 metals, and metal values, in general, increased for 9 of the metals. Output of nonmetal commodities was mixed, with 24 nonmetals showing increases, 20 showing decreases, and 2 unchanged. Nonmetal values were also mixed in 1982: 25 showed increases, 20 declined, and 1 was unchanged. Improvements in the international metals market have not been forthcoming because of the continued depressed prices for major metals. Governments in foreign producing countries have been concerned with maintaining employment and continuing foreign exchange flows through mineral exports. Consequently, the excess of supply in the face of shrinking demand brought downward pressure on metal prices in general, except for the precious metals. On the domestic front, this situation means U.S. mining companies must become even more cost efficient. The major trend in the mining industry in 1983 was to cut costs further, reduce or stabilize total production, reduce outlays for major capital equipment, modify existing systems and equipment, and streamline operations. Most of the accomplishments reported herein reflect this trend.

Jan 1, 1984

This Volume documents the Phase 111 effort on the Seismic Detection and Location of Isolated Miners on Contract H0122026 undertaken during the fall of 1972 by a task team composed of ADL staff and several seismic consultants. The team was assembled specifically to work together on complementary tasks, at an accelerated level of effort for four months, to meet the Bureau of Mines' time schedule for obtaining independent, objective, technical judgments regarding seismic methods and systems for detecting and locating isolated miners. The impetus for this work resulted from a compilation and analysis, during the first half of 1972, of new experimental data obtained from a series of in-mine field tests conducted by Westinghouse Corp .+ using the CMRSS* interim seismic location system. The Bureau of Mines took advantage of the availability of these new data to reassess the potential and limitations of various seismic methods and systems, and to direct its seismic system improvement program accordingly. ADL assisted the Bureau in this reassessment by drawing on the skills of seismic consultants from industry, universities and government, to supplement the skills of the ADL project team. The consultants were principal resources of broadly-based and detailed technical expertise in the areas of seismic signal-source and signal-propagation characteristics, natural and cultural seismic noise, seismic sensors and field instrumentation, seismic signal and data processing for detection and location, and overall seismic system utilization in the field under operational emergency conditions. Specifically, the participating consultants were: F. Crowley, Air Force Cambridge Research Laboratories ; W. Dean, Teledyne Geotech, Alexandria Laboratories; R. Greenfield, Pennsylvania State University; J. Kuo, Columbia University; D. Peters and R. Crosson, University of Washington; and F. Pilotte, U.S. VELA Seismological Center. The principal ADL participants were J. Ginty, R. Lagace, M. Roetter, and R. Spencer.

Jan 1, 1974

By Wm. W. Odell

In distributing natural and mixed gas, the industry is each year confronted with the problem of manufacturing gas in increasing amounts as the supply of natural gas becomes more nearly exhausted. The manufactured gas is now used in mixtures with the still available natural product, and will subsequently be used straight as a substitute gas. The gases that might be considered, and are producible by tried and developed processes, include water gas, carbureted water gas, and coal gas. Singularly, these gases can be used in this manner in ordinary appliances only when proportional amounts of them in the mixtures do not vary beyond rather definite limits, unless burner adjustments are made. The limits are defined by the specific gravity, content of inerts, and burning properties of the respective gases. Anticipating a future standard for city gas lower than that of natural gas during the period when considerable natural gas is available, there is justification for considering the possibility of re-forming natural gas and making a product that has substantially the same properties as other gases which can readily be generated. This report gives the results obtained during a series of tests made under a cooperative agreement by the U. S. Bureau of Mines with the Ohio Fuel Gas Co., re-forming natural gas at Toledo, Ohio, in full-scale operation in a water-gas generator having a grate area of 25.1 square feet. ACKNOWLEDGMENTS The Ohio Fuel Gas Co. constructed a special water-gas generator for the tests and provided men and the necessary funds for its operation. Appreciation is expressed for the general spirit of helpful cooperation which was evidenced in the activities of all those who took part in the work. Particular acknowledgment is made of the assistance rendered by C. W. Wallace, manager, and by C. F. Cramer, superintendent, and A. Upp, foreman of the plant.

Jan 1, 1929

By Roy Greenfield

Estimates are given for the distance from a seismometer at which a miner can probably be detected. The procedure in making these estimates was to first establish the natural noise levels at the output of a surface seismometer for the 25 to 100 Hz frequency passband. The noise levels give the range of values which may be expected in areas with no man-made noise. For each noise level, we give the detection threshold which, when exceeded, indicates that a signal has been received. Based on the signals recorded by Westinghouse, curves are given which show the peak signal amplitude as a function of source- to-receiver distance (slant range). Curves are given for the Westinghouse seismic thumper, a 50-pound timber, and a sledge. For a given type of source, the receive signal strength depends more strongly on slant range than on any other factor. However, there is approximately a five-to-one scatter in the amplitudes. Thus, further study of factors affecting the signal amplitude might allow better estimates to be made for any particular geological setting. Combining the signal amplitude with the detection thresholds for the different noise conditions gives the distances at which a miner should be detected. These are given in Table l* below. [ ] The text also gives the increase in detection ranges which should occur if steps are taken to increase S/N by 10 dB. We feel that 10 dB is a conservative estimate of the improvement possible. During an actual rescue operation, the seismic crew and system should be capable of making on-site estimates of their detection capability, based on measurements of the site noise, and upon the best available estimates of the

Jan 1, 1974

Develop a method to evaluate the effectiveness of coal scam fire surface seals so that potential problems may be corrected at an early stage, before the integrity of the surface seal is lost. Background Surface seals are the primary coal seam fire abatement method being used in the western United States. Surface seals smother a fire by denying it oxygen. The seal is usually constructed by placing a mantle of soil, four to ton feet thick, over a coal scam fire area to exclude air from the fire. The soil is compacted to increase effectiveness, and a soil cement may be used to augment the soil. In some cases, burning coal may be excavated and separately smothered or otherwise extinguished in another area; in other cases, a trench maybe excavated and backfilled with incombustible material to isolate a fire. More often, a surface seal is simply applied over and around the entire known burning area. In the 1950's, the Bureau of Mines administered a large program to treat numerous coal seam Fires across the western United States. Methods used in this program were described in Bureau of Mines Information Circular (IC) 7932, dated 1959. More recently however, various coal seam fires have been treated with surface seals under the direction of state Abandoned Mine Land Reclamation authorities. It has frequently taken years to evaluate the effectiveness of surface seals. By the time problems become evident, it has often been too late to take corrective action within the scope of the original abatement project. For this reason, the Bureau of Mines developed a means for tracking temperature trends at coal seam fire projects to obtain a better and earlier handle on the effectiveness of surface seals.

Jan 1, 1991

By J. A. Herdlick

"INTRODUCTION The Bureau of Mines began a broad program of exploration of various proportion in the Pine Creek area of the Coeur d'Alene mining region in the fall of 1943. As a part of this project, exploring was done at theLittle Pittsburg property in 1945. The work included driving a 500-foot crosscut from the No, 6 level and drilling four diamond core drill holes to test the behavior of the Little Pittsburg vein at depth. This report presents the data obtained by the Bureau.ACKNOWLEDGMENTSIn its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources, to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyses samples and performs beneficiation tests.The Bureau's exploration of the Little Pittsburg vein was one of the activities of the Albany Division of the Mining Branch, S. H. Lorain, chief. The project was started by R. M. Gammell, mining engineer, and was continued by the author and J. R. Reynolds, assistant mining engineer.The chemical analyses included in this report were made at Reno, Nov., under the direction of A.C, Rice, acting engineer in charge, Rare and Precious Metals Experiment Station, Bureau of Mines.The cooperation and assistance of the management of the Denver Development Co. is gratefully acknowledged, in particular that of C. E. Nugent, who made available much of the operational data included in this report."

Jan 1, 1947

By E. W. Dean

In the early winter of 1919 the Pittsburgh petroleum laboratory of the Bureau of Mines undertook the work of testing fuel oil samples representing purchases of the United State Shipping Board for ships sailing from the port of New York. fuel oil was, at this time, being bought on a contract which involved specifications issued by the United States Navy under dace of October 2, 1920 (See Bulletin 1, Oil Division, U. S. Fuel Administration.)The object of the Bureau of Mines in undertaking this inspection work was twofold. (1) The Bureau was in position to give, and the Shipping Board needed, reliable laboratory service for checking the quality of the fuel oil purchased, the value of which ran into millions of dollars for,year's supply. (2) It was believed, and later demonstrated, that the existing specifications did not insure the obtaining of a reliably satisfactory quality of oil.The objection to the specifications concerned the employment of a clause limiting the gravity of the oil. The inadequacy of gravity specifications for several types of petroleum products has long been recognized, and there was every reason to reason to believe that they were no more desirable for fuel oil than for gasoline, kerosene, or lubricating oil. A first and obvious objection was the fact that it is somewhat difficult to make accurate gravity tests on ""heavy"" residuum fuel oils. (The Bureau found it necessary to employ or such tests a rather tedious procedure involving the use of a picnometer and an accurate balance, as the simpler methods, employing hydrometer or displacement balance, proved unreliable in a large proportion of cases.) A second and more important objection was that gravity tests, even when accurately made, do not provide a reliable index of the actual quality of the oil.

Feb 1, 1921

By P. A. Surgeon, R. R. Sayers

It is not the purpose of this report to try to describe all the work done during the past year for the improvement of health or the prevention of illness among miners , but to call attention to a few of the more outstanding investigations in which progress has been made . Among these , the investigations on the physiological effects of carbon monoxide , dust and ventilation , and temperature and humidity will be discussed . Carbon Monoxide . During the years 1920 and 1921 , much more work has been done on the various A survey phases of carbon monoxide than has been carried on for a number of years . of carbon monoxide poisoning in the American steel works , metal mines , and coal He conmines was made by Dr. Henry S. Forbes , of the Harvard Medical School . ** cludes from his survey that late after- symptoms following acute severe gassing rarely occur , and that almost always there is evidence of pre - existing pathological conditions when such effects do appear . He further states that he found no evidence of cumulative harmful effects resulting from frequent exposure . Dr. Forbes , Dr. Forbes , assisted by Louise Hompe , made a laboratory investigation in which anesthetized animals were exposed to carbon monoxide , illuminating gas , and benzol *** . The investigators conclude that , under the conditions of their experiments , there is no change in the coagulation time of the blood . It has been stated by many investigators that the blood of those affected by carbon monoxide does not clot as quickly as normal blood . While the investigation referred to above may not cover all the conditions , it is a valuable contribution to the subject as it indicates that the small hemorrhages found in the membranes covering the central nervous system , abdominal organs , etc. , at autopsy of those dying of carbon monoxide poisoning is probably not due to direct toxic action of the gas upon the blood .

Feb 1, 1922

By Launa Mallett, Michael J. Brnich

The first step to emergency preparedness is defining and analyzing hazards. Although all hazards should be addressed, resource limitations usually do not allow this to happen all at once. Risk assessments are used to establish priorities so that the most dangerous situations are addressed first and those least likely to occur and least likely to cause major problems can be considered later. While the examples provided in this training package are specific to mine fires, the concepts and tools can be applied to any mine hazard. Purpose: This training package was developed to assist instructors, as they: 1) determine how to use risk assessment to improve preparedness for mine fire emergencies and 2) present risk assessment concepts and tools to trainees. Audience: This package is appropriate for workers/trainees from all types of mines. A risk analysis can be conducted by anyone familiar with the location(s) being studied. Why Conduct a Fire Risk Assessment? During a risk assessment, hazards are evaluated in terms of the likelihood that a problem may occur and the damage it might cause. Mine fire preparedness requires consideration of all possible fires that could occur. However, at a given mine some fires are more likely than others and some would result in greater damage than would others. Conducting a risk analysis identifies these differences. The results can be used to target resources at the types of fires that are most likely and/or are most destructive. Hazards that are very likely to result in fires that would do considerable damage to people and property should be targeted first for remediation and/or effective response if remediation isn't possible. Potential fires that are less likely or that would have less severe consequences are identified for attention later, after the more serious situations have been addressed.

Jan 10, 1992

By R. J. Matetic

The National Institute for Occupational Safety and Health (NIOSH) has recognized that Noise-Induced Hearing Loss (NIHL) is the most common occupational illness in the United States. The use of heavy equipment, the drilling of rock, and the confined work environment are some of the factors that contribute to high levels of noise exposure to workers in the mining industry. Every day 80% of the nation’s miners go to work in an environment where the time weighted average (TWA) exceeds 85 dBA. Moreover, 25% of the miners are exposed to a TWA noise level that exceeds 90 dBA, the Permissible Exposure Limit (PEL). Furthermore, a NIOSH analysis of a large sample of audiograms showed that at age 50 approximately 90% of coal miners and 49% of metal/non-metal miners have a hearing impairment. By contrast, only 10% of the non-occupational-noise exposed population has a hearing impairment at age 50 (Franks, 1997) (Stephenson, 1998). Simply stated, the majority of miners have a hearing loss by the time they retire. While NIHL is the most common occupational disease in this country, this problem is especially acute among workers in the mining industry. There are several barriers to reducing NIHL in the mining industry. These include: gaps in knowledge of noise dose/source relationships, the unavailability of effective noise controls, and needs for worker education and worker empowerment. A related issue is the difficulty of communication in noisy workplaces by both hearing impaired and normal hearing workers. The Pittsburgh Research Laboratory (PRL) at NIOSH has strategically developed a hearing loss prevention program for overcoming these respective barriers in an attempt to reduce NIHL in the mining industry. This paper provides an overview of the research program being conducted at the PRL.

By Martin Hertzberg

The Bureau of Mines 8-liter flammability system was used to study the effectiveness of a variety of powdered inhibitors in preventing the propagation of explosions of coal dust or methane in air. Over 35 different chemical additives were evaluated against Pittsburgh seam pulverized coal. The least effective inhibitors were the carbonates, which required mass additions in the range of two to three parts inhibitor to one part of coal dust in order to prevent propagation. The most effective inhibitors were the derivatives of ammonium phosphate, which were effective quenching agents at additions of only one part inhibitor to four parts of coal dust. Alkali halide powders were of intermediate effectiveness. These laboratory-scale results are in good agreement with full-scale mine experiments in all cases where detailed comparisons have been made. Data were also obtained for the effectiveness of several of the same powdered inhibitors against methane-air explosions. Their relative order of effectiveness and the concentration ranges required for quenching the gas explosion are comparable to those measured for coal dust explosions. Data are also presented for the effectiveness of N2 and CF3Br addition. Some preliminary data are also presented for powder addition to methane burner flames. Those data are compared with other burner data and evaluated in terms of their relevance to explosion tests.

Jan 1, 1982

By J. J. Demeter

Anthracite from the four producing regions in Pennsylvania was both ashed in the laboratory and burned on a chain-grate stoker to determine the sulfur-retention properties of its ash. The retention of sulfur in laboratory-prepared anthracite ash was shown to be related to ashing temperature and to the amounts of sulfur and calcium present in the coal. At the usual laboratory ashing temperature of 750° C sulfur retention ranged from 0.8 to 13.2 percent of the total coal sulfur. Sulfur retention in the ash was negligible, o to 0.3 percent, at 1,200° C, which is the thermal decomposition temperature of calcium sulfate; thus calcium sulfate does not form and cannot serve as a sulfur-retaining agent. In several tests the anthracite was mixed with 6 or 10 percent dolomite prior to firing in the chain-grate stoker. The dolomite did not improve sulfur retention owing to the high temperature in the fuel bed. Sulfur retention was, however, related to the unburned carbon in the ash. The relationship of the percentage of original coal sulfur retained in the ash (Y) to the percentage of the original carbon in the coal remaining in the ash (X) is expressed by Y = -0.579 + 0.914X. The percentage of sulfur retained is almost directly proportionate to the percentage of original coal carbon in the ash.

Jan 1, 1968

By H. H. Schrenk

[A colorimetric method5/ for the determination of benzene in amounts as low as 0.001 mg has been developed recently at the U.S. Bureau of Mines Pittsburgh Experiment Station by the authors, with the assistance of chemical personnel fro a the Allegheny County (Pa.) Relief Works Division. The method is based on the direct nitration of either liquid - or gas - phase benzene, followed by neutralization, extraction with butanone, and final treatment with sodium hydroxide which produces a violet color. The color is matched with color standards of known values. Although the method is adaptable to many conditions the primary objective was a procedure that would be suitable for hygienic investigations. The development worth included a study of possible interference by chemicals that be present in those situations in which the method. would be employed. In this study it was found that a specimen of hexane prepared by the Gulf Research Laboratory, Pittsburgh, by fractionation of West Virginia natural gas gave positive result for benzene, whereas a specimen of pentane prepared in the same manner showed only a trace, and specimens of n -heptane and octane (2,2,4 trimethylpentane) supplied by Eastman Kodak Co. save a negative result. According to information obtained from the Eastman Kodak Co. the latter two compounds were highly purified, the n-heptene being prepared from line and the octane synthesized in the laboratory. On nitration of a larger amount of tae natural hexane a visible quantity, of needlelike crystals which resembled those of m-dinitrobenzene was obtained. The hexane from this nitration was recovered by distillation and again nitrated, but no crystals or colorimetric indication of benzene was obtained. This imitated that the specimen of natural hexane contained a substance which at least had the chemical behavior of benzene.]

Jan 1, 1935