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Most cases of bacterial endocarditis involve infection with viridans streptococci, enterococci, coagulase-positive staphylococci or coagulase-negative staphylococci. The choice of antibiotic therapy for bacterial endocarditis is determined by the identity and antibiotic susceptibility of the infecting organism, the type of cardiac valve involved (native or prosthetic) and characteristics of the patient, such as drug allergies. Antibiotic therapies discussed in this report are based on recommendations of the American Heart Association. Treatment with aqueous penicillin or ceftriaxone is effective for most infections caused by streptococci. A combination of penicillin or ampicillin with gentamicin is appropriate for endocarditis caused by enterococci that are not highly resistant to penicillin. Vancomycin should be substituted for penicillin when high-level resistance is present. Resistance of enterococci to multiple antibiotics including vancomycin is becoming an increasing problem. Native valve infection by methicillin-susceptible staphylococci is treated with nafcillin, oxacillin or cefazolin. The addition of gentamicin for the first three to five days may accelerate clearing of bacteremia. Infection of a prosthetic valve by a staphylococcal organism should be treated with three antibiotics: oral rifampin and gentamicin and either nafcillin, oxacillin, cefazolin or vancomycin, depending on susceptibility to methicillin. Vancomycin is substituted for penicillin in patients with a history of immediate-type hypersensitivity to penicillin.

A general investigation was made of the thermal expansion of various silicate fluxes The fluxes considered in the crystalline (anisotropic) and glassy (isotropic) states. were ten feldspars, two nepheline syenites, anorthosite, aplite, and lepidolite.

The fundamental properties of nepheline syenite, such as thermal expansion and fusion characteristics, are given. Test specimens of twelve bodies, comprising various flux combinations of nepheline syenites and potash feldspars with talc, whiting, magnesium carbonate, and pyrophyllite, were fired to seven different cones. The firing linear shrinkage curves of combinations of nepheline syenite with the. various materials are somewhat similar to such combinations with potash feldspar except that the syenite combinations are active at lower temperatures. That the sintering ranges of nepheline syenites are longer than those of potash feldspar is explained thermochemically.

Samples of nepheline syenite prepared by conventional and by fluid-energy reduction methods were studied to determine (1) their fundamental properties and (2) the characteristics they impart to vitreous bodies. Fluid-energy grinding methods make it possible to obtain materials which pass a 325-mesh sieve and yet do not have excessive amounts of extreme fines. The absence of large flux particles is conducive to a uniform distribution of the resultant glassy phase which permits a closer approach to equilibrium conditions and improves the physical properties of whiteware bodies.

By introducing nepheline syenite in sanitary porcelain in reduced amounts to replace potash feldspar, a longer vitrification range is afforded which results in less warpage. Ware fluxed with nepheline syenite has a steel-like ring, the pitch being higher than the regular ware. An electrical machine for producing pure tones was used to classify the various pitches. An oscillograph was used to determine decrement or tone decay. Nepheline syenite, ground to near pottery-grade fineness, was air-separated into coarse, medium, and fine divisions. When used in a porcelain body, the fine division afforded a longer vitrification range, lower warpage, and increased mechanical strength. The sound properties of these bodies are classified. Photomicrographs of body structures are included.

(1) A survey is given of European research on over-glaze decorated tableware tested with various solutions, which are indicated as simulating practical service. (2) A study has been made of some typical European and American tableware with overglaze decorations tested in commercial dishwashing solutions and also in various other solutions which may be encountered in service. Results indicate that acids are harmful on cobalt blues in practically all cases. Alkalis are harmful to practically all decorations, apparently through the destruction of the flux used in preparing the colors. Some commercial cleaning solutions are much more destructive than others.

Small additions of ground nepheline syenite tailings were incorporated into various sewer-pipe bodies. The lost-cost tailings contained 2 to 3% Fe2O3 and significantly improved the physical properties of the sewer-pipe bodies.

The physical properties of wall-tile bodies and floor-tile bodies are described. The wall-tile bodies are fluxed respectively with nepheline syenite; feldspar; talc and feldspar; talc and syenite; talc, pyrophyllite, and syenite; and talc, pyrophyllite, and feldspar. Floor-tile bodies, developing at lower temperatures, may be formulated with nepheline syenite. The greater refractoriness of American clays used in these bodies, as compared to English clays, is compensated for by the increased fluxing action of nepheline syenite.

Results are given on the physical properties of eight bodies, comprising that of a typical semiporcelain and seven bodies incorporating different nepheline syenites, both singly and in combination with feldspar, respectively. The relative viscosities of four nepheline syenites, a typical potash feldspar, and a soda feldspar are compared at five different temperatures. This study is to be followed by comprehensive plant tests.

The effects of kiln atmosphere on a low-maturing shale and a moderately refractory fireclay fired in a pilot shuttle kiln using natural gas were studied. Bricks were fired in both oxidizing and reducing atmospheres, with emphasis on variable water vapor concentrations. The chemical and physical benefits of proper atmosphere selection and control are shown. Kiln atmosphere influenced absorption, shrinkage, strength, scumming, lime popping, frost resistance, and temperature uniformity. Results indicate that firing techniques with rapid schedules and significant reductions in maturing temperatures are feasible without sacrificing product quality.

Color development of shale and fireclay bricks fired and cooled in various atmospheres was evaluated. Iron oxide is the primary colorant in most brick clays; the key to color development and control flexibility is control of the oxidation state and physical or mineralogical state of the iron in the brick, e.g. whether iron is present in a glassy phase, as free oxides, or in a more complex crystalline phase. The influence of H2O vapor on black core elimination was studied. Increasing H2O vapor concentrations in oxidizing atmospheres greatly accelerate the elimination of carbon by the water-gas reaction. The improved burnout depends on the type of carbon in the raw material, since carbon must be present above the temperature at which the water-gas reaction becomes effective.

Five-inch plates indicating promising results were made from semivitreous bodies prepared (1) by introducing the syenite in reduced amounts and (2) by counteracting the greater fluxing action of the syenites as compared to feldspar by reducing the firing temperature. These plates passed autoclave, heat shock, impact, and chipping tests satisfactorily. When the plates embodying syenite failed after repeated tests, the failure was caused by dunting. In no case did crazing occur. Bodies in which equal parts of syenites were substituted for feldspar gave increased values for modulus of rupture and modulus of elasticity, but for the same degree of absorption the values fell within the same range. The syenite bodies showed less tendency to warpage than the feldspar body. The linear coefficient of expansion of the syenite bodies is greater than the corresponding feldspar body, and bodies combining feldspar and syenite are intermediate in this respect. Photomicrographs of body structure are included.

A series of hotel chinaware bodies, based on a commercial body composition, was prepared. The greater fluxing activity of nepheline syenite compared to potash feldspar was compensated for (1) by lowering the firing temperature, (2) by reducing the amount of the principal flux, and (3) by reducing or eliminating the auxiliary flux.