The Arab alchemists before the thirteenth century are as silent as the Greeks: nothing that can be identified with saltpetre is to be found in their voluminous works. The evidence of Geber, so often cited to prove that saltpetre was known to the Arabs in the ninth century, has been stripped of all authority by M. Berthelot, who has satisfactorily proved that there were two Gebers. The real Arab, Jabir, says nothing of saltpetre, but he mentions a salve used by naphtha-throwers[25] as a safeguard against burns. The other Geber, or pseudo-Jabir, was acquainted with saltpetre, as well he might be; for he was a western who lived some time about the year 1300,[26] and wrote a number of Latin works falsely purporting to be translations from the Arabic of the real Jabir. All doubt about the matter has been removed by M. Berthelot’s publication of the real Jabir’s Arabic writings.[27] It has been also suspected that the _sal Indicus_ of the _Liber Sacerdotum, cir._ tenth century,[28] a salt again mentioned in the _Liber Secretorum_ of Bubacar, _cir._ 1000,[29] means saltpetre. Both these works are translations from the Arabic or Persian,[30] and _sal Indicus_ is the literal translation of the Persian—نمك هندي (nimaki Hindi) = نمك سياه (nimaki siyah) = salt of bitumen; a substance of the same family as the “salt of naphtha” also mentioned by Bubacar. There is no word for saltpetre in classical Sanskrit, _sauverchala_ being a generic term for natural salts, which corresponded to, and was as comprehensive as the _nitrum_, _spuma nitri_, &c., of the West. “Recent Sanskrit formulæ for the preparation of mineral acids containing nitre, mention this salt under the name of _soraka_. This word, however, is not met with in any Sanskrit dictionary, and is evidently Sanskritised from the vernacular _sora_, a term of foreign origin.”[31] Both Professor H. H. Wilson and Professor M. Williams, in their Sanskrit dictionaries, “erroneously render _yavakshara_ as saltpetre, as also does Colebrooke in his ‘Amara-kosha.’”[32] The word means impure carbonate of potash obtained by the incineration of barley straw.[33] At length, however, notwithstanding coarse scales and clumsy apparatus, the want of all means of registering time and temperature, and the absence of any general principle to guide them in their researches, the alchemists succeeded in differentiating certain natural salts from the rest, and among them saltpetre. The Chinese were acquainted with it about the middle of the thirteenth century.[34] Abd Allah ibn al-Baythar, who died at Damascus in 1248, tells us that the _flower of the stone of Assos_ was called _Chinese snow_ by the Egyptian physicians and _barūd_ (_i.e._ saltpetre) by the (Arab) people of the West.[35] Friar Bacon, whose _De Secretis_ was written before 1249, and Hassan er-Rammah who wrote 1275-95, were thoroughly acquainted with the salt. A grand chemical discovery had been made, and saltpetre became known from China to Spain.