The principal Use of this Mucilage is to lubricate the Joints, and to render and preserve the Extremities of the Bones, at their Articulations, smooth and supple, for the easy Performance of animal Motion. Besides this mucilaginous Liquor from these Glands, there is an oily medullary kind of Substance transmitted through the very Bone into the Cavity of the Joints: These two Liquors are mixed by the Motion of the Joints, the Mucilage contributes to make the Oyl more slimy, and the Oyl preserves the Mucilage from stiffening into a Jelly. This Mucilage further serves to prevent the Extremities of the Joints from being burnt up in the Gout. In the same Manner the Muscles and Tendons are lubricated and kept in Vigour by the Liquor supplied from the same kind of Glands placed on their Membranes. SECT. 9. This Mucilage is formed from the purer Part of the Lymph and the serous Parts of the Blood, and separated in these Glands from the Mass of the Blood. In order to have a more distinct Notion of its constituent Parts, and to know how it comes to occasion the Gout, the following Experiments of Dr. _Havers_ may be very properly repeated in this Place. He made most of the Trials both when it was hot and when it was cold. Vinegar dropt into it, when it was hot, made a considerable Coagulation with a _Serum_; it must be observed that those Mixtures that were made with it cold, did produce the same Effect when it was warmed, namely a Coagulation with Acids and Stypticks, only in an higher Degree: And whereas the Coagulations, which were made when it was in one State, did only change it into a thick Jelly without any _Serum_, after the Manner of a Cheese when it is newly set, as they term it, which over the Fire afterwards exhibited two distinct Parts, a _Coagulum_ and a Whey; in the other, that is, when the Mucilage was hot, the Mixtures which coagulated it produced an harder Curd, and a _Serum_ distinct from it. By dropping in some of the Decoction of Galls into it, the whole turned into a gelatinous Mass, and it was all a Sort of _Coagulum_ like a Skin, of a whitish Colour, and so tough as to hang all together when it was taken up with a Needle. This _Coagulum_ or Jelly being laid in the Sun, and dried, the Parts of it stuck all together in one Piece, but was very friable and easily rubbed to a Powder, which was very much like fine Flower. The same Effect had the strong Infusion of Balaustia, red Roses, Pomegranate Bark, and the _Peruvian_ Bark, although there was some Difference in the Coagulation, according to the different Degrees of their Astringency. With a few Drops of _Aqua Fortis_ distilled upon it, the Mucilage was immediately coagulated, though the _Coagulum_, which was white, was so tender, that it would by Agitation be dissolved in fair Water, and make it of the same Colour almost like Milk; Spirit of Nitre made exactly the same Alteration in it as _Aqua Fortis_ did, a _Coagulum_ which was of a white Colour. Vinegar, Spirit of Salt of