_Sublimation of Alkaloids._--The late Dr. Guy, F.R.S., directed the attention of microscopists to the fact that the crystalline shape of bodies belonging to the inorganic world might be of service in medical jurisprudence. Subsequently, Dr. A. Helwig, of Mayence, investigated this subject, and found the plan applicable not only to inorganic but also to organic substances, and especially to poisonous alkaloids. By using a white porcelain saucer Dr. Guy was able to watch the process of crystallisation more minutely, and to regulate it more exactly. He was, in fact, able to obtain characteristic crusts composed of crystals of strychnine weighing not more than 1/3000th or 1/5000th of a grain. Morphia affords equally characteristic results. For the examination of these, Dr. Guy recommended the use of a binocular microscope with an inch object-glass. But it is not to crystalline forms alone that one need trust; the whole behaviour of a substance as it melts and is converted into vapour is eminently characteristic, and when once deposited on the microscopical slide, under the object-glass, the application of re-agents may give still more satisfactory results. The re-agents, however, which are here to be applied are not of the kind ordinarily employed. Colour-tests under the microscope are, comparatively speaking, useless; those that give rise to peculiar crystalline forms are rather to be sought after. For instance, the crystals produced by the action of carbozotic acid on morphia are by themselves almost perfectly characteristic. These experiments should not, however, be undertaken for medico-legal purposes by one unskilled in their conduct, for the effects of the reagents themselves might be mistaken by the uninitiated for the result of their action on the substance under examination. For the special method of procedure, see Dr. W. Guy, “On the Sublimation of the Alkaloids.”[34] The Micro-spectroscope. Spectrum analysis has, from its first introduction by Kirschoff in 1859, maintained its fascination over men of science throughout the civilised world. Microscopists, astronomers, and chemists have assigned to the spectroscope a highly important position amongst scientific instruments of research. At quite an early period of its history it appeared to ourselves to promise an extension of the work of the microscope in pathology and microscopy, and second only to that of astronomy and chemistry. The chief hindrances to the use of the spectroscope were, in the early days, of a twofold nature; a widespread, but quite erroneous view of the serious difficulties of employing the instrument, and the want of a first aid to its use.