S to the kinds of earth, that which is filtered through water passes into stone in the following manner:-The water which mixes with the earth and is broken up in the process changes into air, and taking this form mounts into its own place. But as there is no surrounding vacuum it thrusts away the neighbouring air, and this being rendered heavy, and, when it is displaced, having been poured around the mass of earth, forcibly compresses it and drives it into the vacant space whence the new air had come up; and the earth when compressed by the air into an indissoluble union with water becomes rock. The fairer sort is that which is made up of equal and similar parts and is transparent; that which has the opposite qualities is inferior. But when all the watery part is suddenly drawn out by fire, a more brittle substance is formed, to which we give the name of pottery. Sometimes also moisture may remain, and the earth which has been fused by fire becomes, when cool, a certain stone of a black colour. A like separation of the water which had been copiously mingled with them may occur in two substances composed of finer particles of earth and of a briny nature; out of either of them a half solid body is then formed, soluble in water-the one, soda, which is used for purging away oil and earth, and other, salt, which harmonizes so well in combinations pleasing to the palate, and is, as the law testifies, a substance dear to the gods. The compounds of earth and water are not soluble by water, but by fire only, and for this reason:-Neither fire nor air melt masses of earth; for their particles, being smaller than the interstices in its structure, have plenty of room to move without forcing their way, and so they leave the earth unmelted and undissolved; but particles of water, which are larger, force a passage, and dissolve and melt the earth. Wherefore earth when not consolidated by force is dissolved by water only; when consolidated, by nothing but fire; for this is the only body which can find an entrance. The cohesion of water again, when very strong, is dissolved by fire only-when weaker, then either by air or fire-the former entering the interstices, and the latter penetrating even the triangles. But nothing can dissolve air, when strongly condensed, which does not reach the elements or triangles; or if not strongly condensed, then only fire can dissolve it. As to bodies composed of earth and water, while the water occupies the vacant interstices of the earth in them which are compressed by force, the particles of water which approach them from without, finding no entrance, flow around the entire mass and leave it undissolved; but the particles of fire, entering into the interstices of the water, do to the water what water does to earth and fire to air, and are the sole causes of the compound body of earth and water liquefying and becoming fluid. Now these bodies are of two kinds; some of them, such as glass and the fusible sort of stones, have less water than they have earth; on the other hand, substances of the nature of wax and incense have more of water entering into their composition. 

γῆς εἴδη

Γῆς δὲ εἴδη͵ τὸ μὲν ἠθημένον διὰ ὕδατος τοιῷδε τρόπῳ γίγνεται σῶμα λίθινον. τὸ συμμιγὲς ὕδωρ ὅταν ἐν τῇ συμμείξει κοπῇ͵ μετέβαλεν εἰς ἀέρος ἰδέαν· [60c] γενόμενος δὲ ἀὴρ εἰς τὸν ἑαυτοῦ τόπον ἀναθεῖ. κενὸν δ΄ ὑπερεῖχεν αὐτῶν οὐδέν· τὸν οὖν πλησίον ἔωσεν ἀέρα. ὁ δὲ ἅτε ὢν βαρύς͵ ὠσθεὶς καὶ περιχυθεὶς τῷ τῆς γῆς ὄγκῳ͵ σφόδρα ἔθλιψεν συνέωσέν τε αὐτὸν εἰς τὰς ἕδρας ὅθεν ἀνῄει ὁ νέος ἀήρ· συνωσθεῖσα δὲ ὑπὸ ἀέρος ἀλύτως ὕδατι γῆ συνίσταται πέτρα͵ καλλίων μὲν ἡ τῶν ἴσων καὶ ὁμαλῶν διαφανὴς μερῶν͵ αἰσχίων δὲ ἡ ἐναντία. τὸ δὲ ὑπὸ πυρὸς τάχους τὸ νοτερὸν [60d] πᾶν ἐξαρπασθὲν καὶ κραυρότερον ἐκείνου συστάν͵ ᾧ γένει κέραμον ἐπωνομάκαμεν͵ τοῦτο γέγονεν· ἔστιν δὲ ὅτε νοτίδος ὑπολειφθείσης χυτὴ γῆ γενομένη διὰ πυρὸς ὅταν ψυχθῇ͵ γίγνεται τὸ μέλαν χρῶμα ἔχον λίθος. τὼ δ΄ αὖ κατὰ ταὐτὰ μὲν ταῦτα ἐκ συμμείξεως ὕδατος ἀπομονουμένω πολλοῦ͵ λεπτοτέρων δὲ ἐκ γῆς μερῶν ἁλμυρώ τε ὄντε͵ ἡμιπαγῆ γενομένω καὶ λυτὼ πάλιν ὑφ΄ ὕδατος͵ τὸ μὲν ἐλαίου καὶ γῆς καθαρτικὸν γένος λίτρον͵ [60e] τὸ δ΄ εὐάρμοστον ἐν ταῖς κοινωνίαις ταῖς περὶ τὴν τοῦ στόματος αἴσθησιν ἁλῶν κατὰ λόγον [νόμου] θεοφιλὲς σῶμα ἐγένετο. τὰ δὲ κοινὰ ἐξ ἀμφοῖν ὕδατι μὲν οὐ λυτά͵ πυρὶ δέ͵ διὰ τὸ τοιόνδε οὕτω συμπήγνυται. γῆς ὄγκους πῦρ μὲν ἀήρ τε οὐ τήκει· τῆς γὰρ συστάσεως τῶν διακένων αὐτῆς σμικρομερέστερα πεφυκότα͵ διὰ πολλῆς εὐρυχωρίας ἰόντα͵ οὐ βιαζόμενα͵ ἄλυτον αὐτὴν ἐάσαντα ἄτηκτον παρέσχεν· τὰ δὲ ὕδατος ἐπειδὴ μείζω πέφυκεν μέρη͵ βίαιον ποιούμενα τὴν διέξοδον͵ λύοντα αὐτὴν τήκει. [61a] γῆν μὲν γὰρ ἀσύστατον ὑπὸ βίας οὕτως ὕδωρ μόνον λύει͵ συνεστηκυῖαν δὲ πλὴν πυρὸς οὐδέν· εἴσοδος γὰρ οὐδενὶ πλὴν πυρὶ λέλειπται. τὴν δὲ ὕδατος αὖ σύνοδον τὴν μὲν βιαιοτάτην πῦρ μόνον͵ τὴν δὲ ἀσθενεστέραν ἀμφότερα͵ πῦρ τε καὶ ἀήρ͵ διαχεῖτον͵ ὁ μὲν κατὰ τὰ διάκενα͵ τὸ δὲ καὶ κατὰ τὰ τρίγωνα· βίᾳ δὲ ἀέρα συστάντα οὐδὲν λύει πλὴν κατὰ τὸ στοιχεῖον͵ ἀβίαστον δὲ κατατήκει μόνον πῦρ. τὰ δὴ τῶν συμμείκτων ἐκ γῆς τε καὶ ὕδατος σωμάτων͵ μέχριπερ ἂν ὕδωρ αὐτοῦ τὰ τῆς γῆς διάκενα καὶ βίᾳ συμπεπιλημένα κατέχῃ͵ τὰ μὲν ὕδατος ἐπιόντα ἔξωθεν εἴσοδον οὐκ ἔχοντα μέρη περιρρέοντα τὸν ὅλον ὄγκον ἄτηκτον εἴασεν͵ τὰ δὲ πυρὸς εἰς τὰ τῶν ὑδάτων διάκενα εἰσιόντα͵ ὅπερ ὕδωρ γῆν͵ τοῦτο πῦρ [ἀέρα] ἀπεργαζόμενα͵ τηχθέντι τῷ κοινῷ σώματι ῥεῖν μόνα αἴτια συμβέβηκεν· τυγχάνει δὲ ταῦτα ὄντα͵ τὰ μὲν ἔλαττον ἔχοντα ὕδατος ἢ γῆς͵ [61c] τότε περὶ τὴν ὕαλον γένος ἅπαν ὅσα τε λίθων χυτὰ εἴδη καλεῖται͵ τὰ δὲ πλέον ὕδατος αὖ͵ πάντα ὅσα κηροειδῆ καὶ θυμιατικὰ σώματα συμπήγνυται.