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An x‐ray microscope is described in which the mirrors are thin optical flats. These flats are mechanically bent to obtain the radius of curvature necessary to focus the image. The adjustable curvature increases the flexibility of the microscope and the ease of focusing the image. The difficulties of grinding and polishing concave cylindrical surfaces are avoided.The degree of smoothness of reflecting surfaces was studied, and the anelastic properties of various mirror materials were investigated to find a material suitable for bending. Highly polished tungsten carbide was found to be an excellent mirror material and does not require an evaporated surface coating of high density metal.The x‐ray microscope promises to be a valuable research instrument.

An investigation of the effects of rolling and annealing on the orientation of individual grains in silicon ferrite strip yielded results which led to the formulation of a theory for the appearance of the ``magnetic'' orientation in the final processed strip. It is proposed that, in a fine‐grained strip of silicon ferrite, those grains which are already in the ``magnetic'' orientation before rolling will keep that mean orientation during rolling but become more highly strained than other grains, and therefore, they will become the portions of the cold‐rolled strip with highest free energy. In the annealing process these highest energy regions will recrystallize first, becoming lowest energy regions which will be able to consume the now higher energy regions surrounding them. Since these nuclei have the ``magnetic'' orientation, the final product also attains the ``magnetic'' orientation.

A simple method is described for making replicas of surfaces for study in the electron microscope. The surface to be studied is cleaned and then coated with a very thin slightly wedge‐shaped film of polyvinyl formal having a range in thickness from about 500 to 750A in 2.5 cm. This film is formed by dipping the prepared surface into a 0.5‐percent solution of the resin dissolved in dioxane or ethylene dichloride and permitting the solvent to evaporate while the surface is held in a vertical position. The replica film is removed by placing the coated surface under water and peeling the film from it. A description of this technique is given in detail. A graph is presented which shows the thickness of resin films obtainable from various concentrations of resin in dioxane, and a table gives the interference effects which may be used for determining approximate thicknesses of thin resin films. Several easy procedures are described for checking the thickness of such films. A technique is described for preparing strong films having a thickness of 100A and an area of 3 cm2 when mounted in air. Such films are very useful when working with the electron microscope and several methods are described for mounting specimens on them, including a conditioning treatment—useful in mounting water suspensions—which makes one surface very hydrophilic. Five micrographs show the results obtainable with the techniques described.

Recrystallization rate curves for a 50 iron 50 nickel alloy are plotted from data obtained using an X-ray spectrometer, and an activation energy is calculated for the reaction. A multiple crystal orientation is found for the as-rolled material, and the cube texture when recrystallized in the range of 500° to 600°C. It is well established that the directions of easiest magnetization in a single crystal of alpha iron are of the form , while for nickel the corresponding directions are of the form . However, when iron is added to nickel the directions persist as the easiest for magnetization until about 25 pct iron has been reached. In alloys containing more than 25 pct iron the directions of easiest magnetization change from to .

A nickel‐molybdenum alloy containing about 20 atom percent of molybdenum exists above 900°C as a cubic close‐packed structure. If this alloy is quenched and then held at temperatures below 840°C, an ordering reaction occurs which results in a slight tetragonal distortion of the cubic structure. This ordered structure requires for its description a tetragonal cell with 2.5 times the volume of the distorted face‐centered cubic cell. The completely ordered structure can be described analytically as follows: space group: C4h5—I4/m; dimensions of unit cell: a0=5.720A, c0=3.564A, c/a=0.6231; atomic positions: 2 Mo in 2(a), 8 Ni in 8(h), x=0.200. y=0.400.