Following the discovery of powder diffraction by Debye and Scherrer, a major improvement of the intensity of diffraction patterns was attained by introducing focusing cameras. The focusing principle is exploited in the Seemann-Bohlin camera and with improved general background in the Guinier focusing camera. Guinier used a bent crystal to focus Ka lines from the target radiation. Das Gupta, Schnopper and Metzger reported a modification of the Seemann-Bohlin camera by replacing the slit with a target positioned on the focusing circle. This was further improved by using a microfocus target, 30 x 100 micron, positioned accurately on the focusing circle, Fig. 1 (a). The arrangement was very successful for determining thermal expansion coefficients of elements and a few superconducting alloys at different temperature regions.

with a repetition rate of only 10 per second would yield an average power of 20 milliwatts-a power somewhat above that presently available (considerably less than 1 /iw). If multiple pumping could be employed, pulsed fields of the order of a kilo-oersted would be sufficient.

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The spectroscopic analysis of the scattered x rays from lithium, lithium oxide, lithium fluoride, beryllium, and boron irradiated by copper target radiation establishes the existence of sharp characteristic modified lines on the longer wavelength side of the primary beam. This is a new type of incoherent x-ray scattering. The K term values of lithium, beryllium, and boron and the L\ term value of fluorine in lithium fluoride have been calculated from the observed modified lines and these are 58.1, 113.6, 199.0, and 40.6 eV, respectively. Taking into account the limits of error in these experiments, the term values obtained by this new method agree well with the values obtained by Skinner by the method of soft x-ray spectroscopy. Evidence obtained until now about the angular dependence of intensity of the newly observed modified lines brings up several interesting points helping to understand the particular process of scattering, and these points have been discussed.