10. Application and uses have frequently been found for materials, which before were supposed to be of no value. The grains, after the brewer has drawn his worts out of them, are generally used for the feeding of cattle; but I do not know that hops, after boiling, have been employed to any purpose. Is there nothing more left in this vegetable, after it has imparted the virtue wanted to the beer? All plants burnt in open air yield alkaline salts, though in a greater or less quantity, according to the quality of the plants. Boerhaave says that those which are austere, acid, or aromatic, yield in their ashes a great abundance of salts, and these being put in fusion, and mixed with flint or sand, run into glass. Hops thrown, after decoction, in no great quantity on the fire, cause the coals to vitrify, or as it is generally termed, to _run into clinkers_. If therefore the remains of the hops were burnt in open air, or in a proper furnace, it seems most likely that no inconsiderable quantity of somewhat like pot ashes might be obtained, and this, considering the many tun weight of hops employed in large cities, and thrown away as useless, might become an object of private emolument to the brewer, and of public benefit to the kingdom. FINIS. FOOTNOTES: [1] Vide Dr. Pringle’s experiments in his book of observations on the diseases of the army, p. 350, 351 & seq. [2] There is a very singular exception in regard to iron itself, in this respect. It is only a certain degree of heat that expands this metal; (and that much less than any other either more or less dense) when melted, it occupies a less space than when in a solid form. This ought to caution us against an entire dependence on general rules, by which nature doth not appear to be wholly restricted. See Mem. de l’Acad. des Scienc. p. 273. [3] See Dr. Lewis’s Philosophical Commerce of Arts, p. 42. [4] See Martine’s Dissertation on Heat. What the degree of cold was which fixed mercury at St. Petersburg, I do not recollect. [5] It requires seven or eight days. (See Dissertation sur la glace par Mons. de Mayran.) Paris edition, 1749. Page 191. [6] Lately, indeed, by such intense cold as can only be procured with the greatest art, and in the coldest climates, mercury is said to have been stagnated, or fixed. [7] By Dr. Hales’s experiments made for discovering the proportion of air generated from different bodies, it appears that raisin wine, absorbed, in fermenting, a quantity of air equal to nearly one third of its volume; and ale, under the like circumstances, absorbed one fifth. [8] In the northern part of England, the usual time of steeping barley in the cistern is about 80 hours. 40 bushels of barley wetted 1 hour, will guage then in the couch 40 bushels, that is, if drained from its exterior moisture.