The best judges date the oldest existing MSS., Paris, 7156 and 7158, at about 1300 A.D., and Abd Allah tells us that saltpetre was known to the Spanish Arabs in the second quarter of the thirteenth century.[138] The saltpetre recipes, therefore, 12, 13, 14, 32, 33, lie between the years 1225 and 1300. We shall call them, for convenience of reference, the “Late Recipes.” No one who carefully studies the remaining recipes can fail to observe that many of them are marked by archaism of style, form and matter, and that they hand down to us ancient alchemical traditions, or traces of them; while others display no such peculiarities. Let us then, again for mere convenience, divide them into two series—the “Early Recipes,” which possess these peculiarities, and the “Middle Recipes,” which do not. To what periods do these two series belong? No. 26, apparently the most modern of the Middle Recipes, will presently be shown to belong to the early part of the thirteenth century, and, as it does not contain saltpetre, its approximate date is 1200-1225. There is no evidence, so far as I am aware, which would enable us to fix the beginning of the Middle or the end of the Early Recipes. The matter, happily, is immaterial; it is sufficient for us to know that the former series is undoubtedly subsequent to the latter, and (as will be shown) quite independent of it. For a reason which will appear presently, the date of the oldest of the Early Recipes depends upon the period at which Moslems began to write upon alchemy. According to Arab authorities,[139] the first Moslem who wrote on the subject was Prince Khalid ibn Yazeed ibn Moawyah, who died in 708. After him came the real Jabir, of the eighth or ninth century; but Masudi, in the tenth century, tells us that there were many other writers on alchemy whose names are now lost.[140] The very earliest date, then, that can be assigned to the oldest of the Early Recipes is the eighth century, say 750. The three series are as follows:— +-------------------------+-------------------+-----------------+ | Early Recipes, | Middle Recipes, | Late Recipes, | | 750- ? | ? -1225. | 1225-1300. | | | | | +-------------------------+-------------------+-----------------+ | 1, 2, 3 6, 7, 8, 9, 1O, | 4, 5, 11, 22, 24, | 12, 13, 14, 32, | | 15, 16, 17, 18, 19, 20, | 26, 27, 28, 29, | 33 | | 21, 23, 25, 34 | 30, 31, 35 | | +-------------------------+-------------------+-----------------+ Looking from the chemical point of view, M. Berthelot divides the recipes into six groups.[141] Those who are interested in the matter will find on examination that, chronologically, his groups harmonise perfectly with the three series given here.