Проведены экспериментальные исследования формирования структуры, фазового состава и свойств керамики на основе карбидов кремния и бора, полученной реакционным спеканием, и установлено, что они существенно за-, и установлено, что они существенно за-и установлено, что они существенно зависят как от состава шихты и параметров карбидных каркасов, пропитываемых кремнием (общей и открытой пористости, формы и размера пор), так и от количества свободного кремния. Показано, что плотность, прочность при изгибе, твердость керамики на основе карбида кремния и карбида бора, получаемой реакционным спеканием, повышаются с ростом давления прессования карбидных каркасов. Наибольшими свойствами обладает керамика на основе карбида бора и карбида бора с 50 % карбида кремния, пропитанная кремнием.

muscle has not been determined. A dye that I have made by linking novocaine with a benzene nucleus was found to be physiologically active, like the 2.5% novocaine, and appears to stain the elements acted upon by the novocaine. When the stain is diazotized directly into the living muscle, by putting the tissue first into novocaine and then into a solution of the staining base, only the muscle nuclei take the stain deeply, the nervous elements of the end-plates as well as the motor fibers remaining uncolored. It seems reasonably certain, therefore, that novocaine acts upon some constituent of the neuro-muscular mechanism beyond the end-plates. The significance of the affinity of the dye for the muscle nuclei is as yet unknown. The object of this note is to direct the attention of physiologists to a convenient substitute for curare.

ABSTRACT

No abstract

Theory of the method.-The pore volume is measured by allowing the gas which fills the pores to expand into a measured volume and measuring the accompanying fall in pressure.Applicability.-The method is in general applicable to pieces of any size and shape and to all classes of porous bodies or materials.A new porosimeter.-For rapid work with shaped test pieces a new porosimeter is described. The new instrument measures accurately both pore volume and bulk volume. A complete porosity determination can be made in 5 minutes.The results on ceramic bodies arc reproducible to one unit in the first decimal place of the per cent porosity. Considerably higher accuracy than this can be secured if desired.Results.-The results obtained with the new method are in all cases higher, in a number of cases very much higher, than those obtained by the methods of liquid absorption in current use. For fired bodies the same results are obtained with dry air, hydrogen or helium as the pore filling gas. The results show conclusively that complete filling of all the pores in a reasonable time can not be secured by any of the current methods using a liquid as the pore filling agent.No weighing is required.