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By Y. M. Zhu

Lead in environment often causes a serious health hazard. The removal of Pb2+ from aqueous phase is a beneficial project. In this paper, deposited Saccharomyces cerevisiae (S.c.) was chosen as adsorbent, Pb2+ ions as adsorbate, and the process of biosorption was studied. The dynamics of the adsorption was investigated. The adsorption mechanism of Pb2+ by S.c. cells was also investigated by detecting microstructure, zeta potential under different pH value, FT-IR spectra of the S.c. particles before and after biosorption. It was shown that the biosorption of Pb2+ by deposited S. c. is a rapid process, and the adsorbing equilibrium is reached within 10 minutes. The Zero point of zeta potential of S.c. cells is pH=3.3. When 2.0<pH<3.3, there exists biosorption (biosorption rate 76%~88%), which means static bio-sorption been not the only kind of biosorption. FT-IR spectrum analysis showed that groups on bacteria surface were mainly characteristic groups of protein and amylase; oxo-groups and nitric-groups on S.c. cell surface could chelate with heavy metal ions. Chemical adsorption might exist in the process.

Jan 1, 2014

By Javier Enrique Basurco Cayllahua

In this work, a gram-positive bacteria was used as biosorbent to elucidate the aluminum load capacity under different conditions related to metallurgical and chemical plants. The sorption data followed the Langmuir, Freundlich, Dubinin-Radushkevich isotherms. In order to determine the best isotherm fit, three error analysis methods were used to assess the data: correlation coefficient (R2), residual root mean square error (RMSE) and Chi-square test. The error analysis established that the Dubinin-Radushkevich model fits better the aluminum biosorption data. The maximum sorption capacity was found to be 41.59 mg.g-1. The maximum removal of aluminum was 95% at pH around 5. The experimental kinetics data was evaluated considering two models (pseudo-second order and pseudo-first order). This study indicated that the R. opacus is an environmental friendly biosorbent.

Jan 1, 2009

By Klara Kodrikova, Vera Kasparkova, Michaela Uhlirova, Karel Kolomaznik

"Potentially hazardous wastes from leather industry (blue shavings) are processed into various biostimulators within two steps. The first step takes place at high pH (11-12) and hydrolyzation is implemented with potassium alkali, in the second step the pH is lowered to 9 with phosphoric acid after enzymatic dechromation occurs. The resulting hydrolyzates were analyzed in the sense of molecular weight distribution and tested as biostimulators on rape (Brassica napus). The hydrolyzates can be also directly used as universal NPK fertilizers. It has been proved that the nitrate content in the edible parts of tested vegetables (radish, lettuce, and cucumber) was approximately 200 times lower compared to the vegetables fertilized with an inorganic nitrogen fertilizer. The harvests of vegetables fertilized with the hydrolyzate and the inorganic nitrogen fertilizer were almost the same.IntroductionDuring processing raw hide into leather (tanning processes), only 20% of the collagen material is used for the final product. The remaining 80% ends up as waste, both tanned and non-tanned. Non-tanned waste such as calcimine can be used for production of artificial collagen casings for sausages, gelatine and also in pharmaceutical industry as collagen capsulates. Further processing and recycling of tanned leather waste (especially chrome shavings) is more complicated. Although many technologies producing various quality collagen hydrolyzates have been developed and tested in laboratories, few have been implemented on industrial scale. A promising turn came in the works of ERRC USDA [1,2]. They worked out an enzymatic dechromation technology (hydrolysis) and achieved a considerable decrease of the amount of relatively expensive proteolytic enzyme, which solved the difference between the quality and price of the final product. The American experience of enzymic hydrolysis were applied on industrial scale in the Czech Republic, where a plant was built with daily processing capacity of 3 tons of chrome shavings. The experience of real operation was published in [3] and the cooperation between the Czech Republic and USA partners resulted in a patent [4]. The main asset of the patent was the use of volatile organic bases in the hydrolysis process giving high quality and cheap hydrolyzates with low ash content."

Jan 1, 2008

By Nelson R. Shaffer

Biotechnology has become a household word of the nineties, and it is expected to become as important in the next century as the computer is in the present. Numerous books and articles portray biotechnology developments as nothing less than a scientific revolution. Almost everywhere one looks new biotechnical breakthroughs are being reported that offer almost limitless opportunities to harness the force of living things to produce materials and manipulate their properties. Biotechnology has been broadly defined as any applications of biological organisms, systems, or processes to manufacturing and service industries. This seemingly new technology is, in fact, one of mankind&apos;s oldest scientific activities (Table l), which has been recently revolutionized by techniques of genetic engineering that arose out of basic research in biology, biochemistry, genetics, and information sciences. From fields as old as agriculture and medicine to those as new as monoclonal anti-bodies, transgenic plants, or biocomputers are encompassed by biotechnology. Like most human endeavors, industrial minerals play critical roles in biotechnology. In addition biotechnology holds real potential to improve extraction and beneficiation of certain industrial minerals themselves. BIOTECHNOLOGY OVERVIEW Companies using established biotechnical techniques make up large and diverse groups such as agriculture, chemicals, and pharmaceuticals. The massive US Pharmacopia (Anon., 1990a) provides detailed specifications for minerals used in medicines. Alumina, zirconia, apatite, and bioactive glass have seen service as implant materials (Williams, 1990) and new uses for minerals in health sciences are being actively researched. Agriculture produced $361 billion worth of food and drink during 1991 in the United States; organic chemicals, pharmaceuticals, and enzymes accounted for $68, $59, and $42 billion, respectively (Anon., 1992a). It is not possible to separate the contributions of industrial minerals to biotechnical products, but they represent a very large and rapidly growing new field of uses. The new biotechnology has nearly 300 small companies, plus 15 established companies with 742 biotechnology-related firms (Dibner, 1991b). Revenues exceeded $2 billion in 1990 and are expected to grow to $50 billion by 2000 (Anon., 1992c), with worldwide sales exceeding $100 billion (Burrill and Roberts, 1992). Federal research amounted to $3.4 billion in 1990 (Anon., 1992b). The United States is the world leader in biotechnology, but other countries have large, well-funded programs. Despite debate about safety, obstacles to new biotechnology products are declining (Embers, 1992, Gibbons, 1991). Fifteen biotechnology drugs valued at $1.2 billion (Thayer, 1991a) are on the market, and more than 100 are in various stages of testing (Edington, 1992). Many diagnostic tests are also in use or development (Demain, 1983, Anon., 1992). Large scale efforts to produce or transform important chemicals are also underway (Ng et al., 1983, Hinman, 1991), and research into geologic uses of biotechnology has begun. Much has been published about microbial mining, oil recovery, desulfurization, bioremediation, and other geologic aspects of biotechnology, but this chapter is the first attempt to explore interactions of biotechnology and industrial minerals. This chapter examines uses of minerals in biotechnology; how biotechnology can be used to discover, recover, and beneficiate industrial minerals; and speculates on some potential, but as yet untried uses. Definitions What exactly does the word biotechnology mean? Bud (1989) states that the first use of the term was by Karl Ereky in 1919 to cover the interaction of biology and technology, and in 1933 the term was used in Nature. After citing seven different definitions, Smith (1988) concludes that biotechnology is a series of enabling technologies involving practical applications of organisms or their subcellular components to manufacturing and service industries or to environmental management. Walker and Cox (1988) suggest a definition of "the practical applications of biological systems to the manufacturing and service industries and to the management of the environment." Primrose (1991) says that it is "the commercial exploitation of living organisms or their components." There is essentially an older broad use of the term and a new use. The US Office of Technology Assessment (Anon., 1984) uses a broad definition that includes any technique that uses living organisms (or parts of organisms) to make or modify products, to improve plants or animals, or to develop micro-organisms for specific uses. Definitions are different, but they all have several fundamental elements that include the control, management, or manipulation of living things for commercial, industrial, or useful ends. While such a definition encompasses all of agriculture in practice the "new" biotechnology is restricted to processes involving microorganisms-plant and animal cells, or enzymes. Many consider biotechnology to be recent, but it is one of our oldest technologies as evidenced by the prehistoric origin of brewing, cheese-making, and other techniques. [Table 1] gives some of the important developments in the history of biotechnology. Smith (1988) breaks down historical developments of biotechnology into four phases: 1) prehistoric with no understanding of underlying processes; 2) nonsterile processes; 3) sterile processes after 1940; and 4) genetic and recombinant DNA technology deliberate design of special organisms or processes.

Jan 1, 1994

By E. Ashirbaeva

"Ores of ferrous metals traditionally make up the bulk of recoverable reserves of solid minerals, and iron ore concentrates - in the processing and consumption. To obtain concentrates, three main methods are used: dry and wet magnetic separation, gravity and flotation. But even their integration into complex developed schemes with finishing operations often do not solve the problem of obtaining high-quality concentrates, which are necessary for powder metallurgy and electric steelmaking. Increasing the iron content in the concentrate by removing harmful impurities is the goal of this work. The possibility of reducing the operations of wet magnetic separation twice and completely eliminating concentrating operations in ball mills from the scheme of operations has been established. Selective leaching agents for each type of iron ores have been created, allowing to obtain concentrates with an iron content of not less than 68-69% and negligible concentrations of harmful impurities. Methodical recommendations for long-term storage of bioreagents in the active state, their immobilization and preparation in industrial conditions at the enterprise Nedropolzovatelja are developed. The proposed biotechnology, which allows to obtain high quality iron and conditional concentrates for harmful impurities, is protected by patents (RU 2537684 ""Method for fine-tuning of high-sulfur magnetite concentrate"" for magnetite ores and Pat. RU 2599068. For the industrial implementation of the new technology, organizational and technological measures have been developed in the system with Road maps for types of ores. The developed technology makes it possible to condition noble metal, tin, tungsten, nickel and other concentrates in harmful impurities such as arsenic, antimony, mercury, sulfur, copper, zinc, iron, phosphorus, manganese, in total 30 components that pass into solution under the influence of bioreagents.INTRODUCTION Consumption of various metals is steadily increasing every year, the volume of mining is constantly increasing. Ores of ferrous metals traditionally make up the bulk of the recoverable reserves of solid minerals. Enrichment technologies for iron-containing ores are reduced to the combination of three main methods: wet and dry magnetic separation, gravity and flotation. But even the use of complex advanced technological schemes often does not lead to the production of high-quality concentrates suitable for metallurgical processing. In this case, either lapping operations or effective technical and technological solutions are used in the main enrichment cycle. Widely used in practice methods for improving the quality of iron ore concentrates include the use of finishing operations (fine screening, reverse cation flotation), staging of concentrates, the use of more sophisticated equipment (separators with running magnetic field, magnetic gravity classifiers, column flotation machines)."

Jan 1, 2018

By T. Nomura, N. Saitoh, K. Tamaoki, Y. Konishi

We have developed new recycling technologies, based upon an eco-friendly biotechnology, in order to extract precious and rare metals sourced from end-of-life products and electronics. We have been focusing on the metal ion-reducing bacteria, Shewanella algae and Shewanella oneidensis, that are able to reduce and deposit gold ions (Au(III)) or PGMs ions (Pd(II), Pt(IV) and Rh(III)) into metal nanoparticles at room temperature within 120 min. When processing the aqua regia leachate of printed circuit boards, Shewanella bacteria were able to rapidly and selectively collect gold ions under acidic conditions in the presence of heavy metal ions, proposing a new bio-recovery system for gold. This biotechnological procedure also has the potential to allow the recovery of PGMs from the leachate of automotive catalysts. Shewanella bacteria were also able to successfully perform the complete reduction and deposition of the PGM ions. The ability to collect the PGM ions suggests that this represents a new process for the biorecovery of PGMs from used automotive catalysts. Our proposed biological method enables the rapid and highly efficient recovery of precious and rare metals via separation and concentration utilizing microbial reactions at room temperature.

Jan 1, 2014

By J. L. Huisman

Bio(hydro)metallurgy is the latest development in the ongoing search for efficient and economic metal winning processes. In addition to bioleaching, other biotechnology-based applications are becoming more and more accepted. In this paper the THIOMET process for general effluent treatment is described. With this process, it is possible to produce sulfide on-site and on-demand and to use the sulfide to precipitate metals, even selectively when required. The process is ideally suited as a treatment to remove metals after, for example, an acid regeneration process. Another process is proposed that deals with stainless steel pickling bleeds. Such effluents typically contain nitrate, iron, nickel, chromium(VI) and other species. This one process handles these compounds, as well as other metals.

Jan 1, 2006

By Patiño E

Bioleaching is an established technology for the pre-treatment of refractory gold ores and concentrates and the leaching of whole ore copper heaps. In many cases, it offers economic, environmental and technical advantages over pressure oxidation and roasting. However for bioleaching to compete successfully with others pre-treatment processes it needs to be optimized with regard to the parameters that affect the bioleaching reactions and the growth of the microorganism involved. In this sense, this paper focus on the thermodynamic approach applied in bioleaching through of the definition of the growth system and it is thermodynamics analysis, the effect of heat production and energy dissipation on growth and thermodynamic analysis of growth kinetics and the effect of nonstandard conditions.

Sep 12, 2005

By L. Bernoth, I. Firth, S. Rhodes, P. McAllister

As biotechnologies emerge from laboratories into main-stream application, the benefits they offer are judged against competing technologies and business criteria. Bioremediation technologies have passed this test and are now widely used for the remediation of contaminated soils and groundwaters. Bioremediation includes several distinct techniques that are used for the treatment of excavated soil and includes other techniques that are used for in situ applications. They play an important and growing role in the mining industry, for cost-effective waste management and site remediation. Most applications have been for petroleum contaminants, but advances continue to be made in the treatment of more difficult organic and inorganic species. This paper discusses the role of biotechnologies in remediation and pollution control from a mining-industry perspective. Several case studies are presented, including the land application of oily wastewater from maintenance workshops, the composting of hydrocarbon-contaminated soils and sludges, the bioventing of hydrocarbon solvents, the intrinsic bioremediation of diesel hydrocarbons, the biotreatment of cyanide in water from a gold mine, and the removal of manganese from acidic mine drainage.

Jan 1, 2000

By Nelson R. Shaffer

Glamorous, burgeoning biotechnology and mundane industrial minerals would at first glance seem to share little in common, but in truth, modern biotechnology depends on many minerals. Biotechnical processes also can be used in industrial mineral extraction and processing. Biotechnology is broadly defined as the application of biological organisms, systems, or processes to manufacturing and service industries. Genetic engineering has reinvigorated one of mankind&apos;s oldest sciences, biotechnology, into a booming business. Many modern processes depend on microorganisms cultivated under very stringent conditions in bioreactors. Minerals from carbonate, sulfate, chloride, nitrate, phosphate, and silicate families are used to provide essential nutrients and to regulate growth conditions (such as pH) in order to assure optimal growth of organisms. Certain cells or enzymes perform better when immobilized upon or within solids, and minerals are often used to immobilize cells, especially in continuous process. Minerals are also used extensively in separating and purifying products of biotechnology. Diatomite, zeolites, and silica are especially useful in purification processes. Industrial minerals also are commonly used to clean up large volumes of process water that must be treated. Biotechnology can be employed in exploration, extraction, and processing of geologic materials and in reducing mining or other environmental problems through bioremediation. Microbes have been shown to solubilize certain elements and so promote extraction of heavy metals, phosphate, aluminum, potassium, and even rare earth elements. In a related technique, unwanted materials such as pyrite impurities can be leached microbially to produce cleaner products in sand and clay industries. Microbial actions can modify surface characteristics and so enhance certain ceramic properties. Certain organisms can accumulate useful elements from dilute sources; others can transform unusable chemical species to more useful forms. Deterioration of stone, concrete, and even glass or brick, can be accelerated by microorganisms. Control of such biodeterioration could improve long-term performance of industrial mineral products. Microbial processes have shown promise in improving several mine-related problems. Certain bacteria help remove clays from phosphate slimes and other suspensions. Others are used to degrade cyanide or other organic chemicals such as floatation aids. Cells immobilized on clays have been especially efficacious in bioremediation. Biotechnology industries, like the industrial minerals industries, encompass huge ranges of materials and processes. Costs of products from these industries range from pennies to thousands of dollars per unit, and their products are vital for maintaining modern life styles. Many biotechnical processes depend upon industrial minerals and certain biological processes can be harnessed to do useful tasks in the minerals field. The interplay of industrial minerals and biotechnology is important today, and as biotechnology advances, its interaction with the industrial minerals industry can only increase.

Jan 1, 1995

By John F. Spisak

Versatile living organisms, historically exploited as functionaries in the food processing, pharmaceutical and chemical industries, have not been successful in achieving similar or significant acceptance within the minerals industry. The current biotechnical revolution coupled with its expanded understanding, dictate that a flagging minerals industry reconsider the use of biotechnology in metallurgical applications. Living resources, either singly, in commensal association or in complex communities, are capable of duplicating fully integrated and complex processing functions. Organisms can mine and extract metals, detoxify chemical effluents and synthetically produce compounds. They have been criticized as exhibiting poor kinetics, excessive energy consumption and environmental sensitivity. However, expanding knowledge reveals that these organisms are surprisingly adaptable, variable and extremely durable. Applied biotechnology in specific cases offers favorable economic returns, environmental benefits and aesthetic value. Selective implementation of living systems can offer opportunities for reduced labor, increased productivity and technological advance. Success will not come easily. Capital must be risked, controversial decisions made and new ground plowed. Traditional, specialist thinkers will of necessity give way to interdisciplinary expertise and unorthodox methodology if success is to be achieved. Those who vigorously persevere, however, are likely to be rewarded with a dynamic and profitable new role in a restructured minerals industry.

Jan 1, 1985

By S. K. Kawatra, T. C. Eisele

"Recent advances in microbiology have made the application of biotechnology to metallurgical processes possible. Hydrometallurgy stands to gain the cost from the use of microorganisms, as they are useful for both dissolution aids and for removing metals from solution. The development of genetic engineering techniques promises to greatly increase the importance of bioprocessing of metals and minerals by the year 2000.In this paper, the basic effects of microorganisms on metallurgical processes are reviewed, and the applications which are currently either in use or near being used are presented. Representative data collected at Michigan Technological University is also given.IntroductionMany hydrometallurgical operations exist which are thermodynamically possible, but which are industrially impractical due to slow kinetics, high reagent costs, or the need for a highly corrosive environment. However, recent discoveries in microbiology indicate that in many cases these difficulties can be reduced greatly by the action of bacteria and other microorganisms (1-8).A major advantage of using living organisms in hydrometallurgy is that once the culture is established the microorganisms produce their own reagents either from the material being processed or from low-cost nutrient supplements. They thus allow extremely complex chemical reactions to be carried out at reasonable cost. The major drawback of using microorganisms is their inability to tolerate extremely high temperatures, excessive concentrations of toxic metals, or very highly acidic, alkaline, or corrosive conditions. However, the complex reactions which bacteria make possible frequently eliminate the need for such extreme conditions. Also, in recent years a number of organisms have been isolated from such exotic environments as hot springs and deep-ocean vents which can tolerate temperatures higher than was previously thought possible for any organism, and can catalyze a number of metallurgically important reactions (8)."

Jan 1, 1988

By D. S. Holmes

Biological processes for metal solubilization and ore beneficiation are in widespread use today. There are also some promising new applications of biotechnology in the areas of metal concentration and toxic metal cleanup. Recent progress in genetic engineering promises both to revolutionize the existing biological process and to expedite the adoption of the new biological applications. But before it can do so effectively, progress must be made in many areas of fundamental research and in biochemical engineering. These issues are addressed with special reference to the biotechnology of semi-enclosed containers (bioreactors), dumps, heaps, in situ and under- ground leaching, and with respect to the biotechnology of metal concentration. Finally, certain biological considerations for bacterial strain improvement are discussed.

Jan 1, 1987

By H. Dijkman

The PAQUES Bio Systems&apos; core technology, marketed under the name THIOPAQ®, consists of various high-rate biological processes for metal-sulfur-water systems, complemented with common solid/liquid and gas separation steps. Sulfur species are converted to sulfide, which is a valuable component as it can be used for metals reduction and precipitation. Selective recovery of valuable metals can be employed, leading to revenue from metal values. In this paper, biotechnological systems for the treatment of metal sulfate solutions and dilute SO, gases are described. These installations can be designed to either produce predominantly aqueous (NaHS) or gaseous (H2S) sulfide. The emphasis here is on hydrogen sulfide gas. The main case history discussed is the demonstration plant that ran on hydrogen gas at Kennecott Utah Copper. Three years of operating experience clearly show that sulfate reduction with hydrogen gas is a viable option. Furthermore, the selective recovery of copper from leach water with the hydrogen sulfide produced was shown to be very effective.

Jan 1, 1999

By A. Kapoor

Gold mill effluents contain toxic pollutants such as cyanide (CN), thiocyanate (CNS), ammonia (NH4-N), and a variety of toxic metals. Various practical and economical technologies are in use for the removal of CN and toxic metals from gold mill effluents, however, the removal of CNS and NH4-N is challenging. The presence of CNS and NH4-N may make effluents toxic to aquatic life. The new Canadian Metal Mining Effluent Regulations will require mine effluents to be nontoxic. As a result, there is a need to develop practical and economical technology for CNS and NH4-N removal. The Mine Effluents Program in the Environment Group is presently evaluating biotechnology processes for the removal of CNS and NH4-N from gold mill effluents. The processes being evaluated are attached growth systems such as a Rotating Biological Contactor (RBC) and completely mixed suspended growth systems such as a Sequencing Batch Reactor (SBR) operating in a batch mode. The research to date at MMSL has shown that the RBC is very effective in removing CNS and NH4-N from simulated effluents. The NH4-N removal project showed that the RBC is capable of removing 0.8 g NH4-N/m2 of RBC disk area per day at an average temperature of 4.5 oC and hydraulic loading rate of 0.02 m3/m2/d. The RBC was also found to be very effective in removing CNS (feed = 200 mg/L and effluent < 1 mg/L) at 8 oC and a hydraulic loading rate of 0.02 m3/m2/d. The SBR was effective in removing CNS and NH4-N (generated from CNS degradation) at SBR operating conditions of two-12 h treatment cycles and a temperature of 12 oC. The end product of CNS and NH4-N oxidation was NO3-N, which is relatively non-toxic.

Nov 1, 2002

By J. D. Bateman

DURING the summer of 1942 several chromite deposits were discovered in the Lac du Bonnet district about eighty miles northeast of Winnipeg. The deposits are confined to the Bird River complex, a folded composite sill of basic and ultrabasic igneous rocks of early Precambrian age that lies to the north of Bird river (1). The outcrop of the sill represents the trace of an easterly plunging anticline, the south limb extending from the northeast bay of Lac du Bonnet eastward to Bird lake, and the other limb, 6 to 12 miles north, lying between Maskwa river and Euclid lake. The south limb of the sill is 20 miles long, and the northern counterpart 15 miles; but its continuity is interrupted by faulting and by the intrusion of younger granite, so that the total length of outcrop of both limbs does not likely exceed 25 miles. The sill is intrusive into early Precambrian greenstones and associated sedimentary rocks. The chromite discoveries have been made at several localities on both limbs of the sill, and in each case at the same geological horizon. The sill comprises an upper layer of hornblende gabbro and a lower layer of serpentinized peridotite, and altogether is from 500 to 3,500 feet thick. The chromite zone is within and near the top of the peridotite layer, and thus about midway of the sill, both of the limbs of which stand nearly vertical. This geological relationship was established early in the exploration of the initial discoveries and served as the basis for successful predictions of later discoveries. The chromite zone probably persists throughout the length of the sill, but its width and chromite content are not everywhere the same. The initial exploration along both limbs of the sill has shown a combined total length of about 12,000 feet of chromite ore varying in width from 6 to 12 feet. In many places the overburden is thick and obscures the continuity of the chromite zone; but as investigation proceeds the known deposits will be extended and new ones will be found. Thus, although a total length of 12,000 feet of ore has been investigated up to the present time, there is an indicated length of approximately 31,000 feet along which the ore is more than 4 to 5 feet wide. This estimate is based on geological considerations and represents a total tonnage in the order of 15,000 tons per vertical foot of depth.

Jan 1, 1943

By Cyril S., Smith

WE cannot but marvel at the fact that fire is necessary for almost every operation. It takes the sands of the earth and melts them-now into glass, now into silver, minium or other lead or some substance useful to the artist or physician. By fire, minerals are disintegrated and copper produced; in fire is iron born and by fire is it subdued; by fire, gold is purified; by fire, stones are burned for the binding together of the walls of houses.... Fire is the immeasurable, uncontrollable element, concerning which it is hard to say whether it consumes more or produces more." Thus wrote Pliny in his "Natural History," that great collection of fact and error which constitutes the principal contemporary description of Roman technology and which until the seventeenth century was the authority most often quoted and requoted by those who wrote on metals, as on many other subjects.

Jan 1, 1940

Jan 1, 1889

Jan 1, 1925

By J. M. Silliman

Several years ago, having occasion to determine the amount of some very slight atmospheric depressions, I devised and had constructed by a skilful tinsmith the manometer shown in the accompanying drawing. It consists of a cylindrical vessel of tin, 6.6 inches in diameter, through the sides of which, at a distance of about six inches from the top, passes an air-tube D, its upper extremity terminating 3.5 inches from the top. Within the vessel is a combined cylipdrical

Jan 1, 1889