In most of these experiments, the needle was made to attach itself to the substances by being forced towards them by a magnet, which was gently withdrawn after contact was so effected. In this way, and by a reference to the degrees of the compass traversed by the needle, a hair of the head, or a spark of diamond, can be accurately measured. The strength of the needle in its movement on a pivot was ascertained by azimuths, of which a detailed account is given. The remainder of the memoir, which is contained in a supplementary number of the Magazine, is devoted to a detail of about five hundred experiments, in which non-ferruginous needles were made, by a modification of the magnetic needle, of which they formed a portion, to attach themselves to the same substances as in the preceding experiments. Thus, for instance, needles of most of the remarkable metals, as well as of glass, were found to have a strong affinity for nearly every kind of substance, whether mineral, vegetable, or animal, if its density was greater than that of cork or charcoal. Brass surpassed all the metals in its power of attraction, and, what is most remarkable, the magnetic needle was the lowest of all in the scale, showing not much more than one-third of the attractive energy of soft iron. Every substance of a crystalline or vitreous character exhibited remarkable magnetic properties, and this could not be mistaken, as it might be heightened at pleasure by contact with either pole of a powerful magnet. Towards the close of the experiments, the curious discovery was made, that needles of ivory, mother-of-pearl, tortoise-shell, horn, etc., were singularly magnetic, and this is traced to the albumen and gelatine they contained; and the inference is drawn, from this and other facts, that the cohesive, adhesive, and viscous properties of bodies are owing to real magnetic qualities, and that, by drying, albuminous, gelatinous, and glutinous fluids constitute various kinds of glass, which view is supported by what takes place with the gelatinous hydrate of silicium. “The preceding experiments,” says the writer, “include a vast variety of substances in the mineral, vegetable, and animal kingdoms, that exhibit such strong attractive affinities for one another, that, however much they may differ in their external appearances, and in their very natures, they are bound together by common bonds that connect them all into a single family; for we find the metal attaching itself to crystalline, animal, and vegetable substances; and, again, the crystal, whether we call it by the name of diamond, salt, or sugar-candy, connecting itself readily to metallic, animal, and vegetable bodies. In a similar way, animal bodies attach themselves to those that are mineral and vegetable; and, to complete the circle, the vegetable kingdom, by its woods, its gums, its lac, and its resins, is connected with them all.” CHAPTER IX.