The price of French powder in 1375 was 120d. per lb.;[450] but in order to be able to compare it with the price of English powder in 1378, we must know the ratio of French to English money at that period. The French Troyes livre then contained 5760 gs.; the English Tower pound 5400 gs. Therefore— 1 livre (pure silver) = 16/15 pound (pure silver). Under Philip of Valois (1328-50) the livre was debased to 1/12 its original value,[451] and almost simultaneously the pound was debased by Edward III. to 4/5 its primitive value.[452] Or 1 good livre was worth 12 bad livres, and 1 good pound was worth 5/4 of a bad pound. Therefore— 12 livres = 16/15 (5/4 pound) = 4/3 pound; or 9 livres = 1 pound. Dividing the price of 1 lb. French powder, 1375, by the price of 1 lb. English powder, 1378, we get 120/13.664 = 8.7; so that the French powder at this period was somewhat cheaper than the English. As the purchasing power of fourteenth-century money was about ten times that of ours, the French powder of 1375 cost about 11s., and the English powder of 1378, 11s. 4½d. per lb. The high price of early gunpowder resulted from high freights and (in the case of saltpetre) the rapacity of Eastern merchants. We may form some notion of the price they exacted for their saltpetre which cost them little,[453] from the price they put upon their naphtha which cost them next to nothing. “Another fountayne there is towarde the Oryent whereof is made fyre grekysshe, with other myxtyons (mixtures) that is put thereto; the which fyre when it is taken and lyght is so hote that it can not be quenched with water, but with aysel (vinegar), urine or sande only. The Sarasynes sell this water dere, and derer than they do good wyne.”[454] The manufacture of gunpowder soon became a trade. We find a powder-mill in Ausburg in 1340, in Spandau in 1344, and in Liegnitz in 1348.[455] There was a gunmaker in Stockholm in 1430, who was very probably a powder-maker too;[456] and it is certain that there was a powder-maker there in 1464—Mäster Berend.[457] Nor were Governments blind to the importance and the profit of the trade. Beckmann states that the Archbishop of Magdeburg in 1419 only permitted the collection of saltpetre on payment of a license,[458] and Clarke informs us that the Pope and the Archduke of Bavaria engaged themselves in powder-making at an early date.[459] Louis XI. appointed commissioners in 1477 to collect all the saltpetre they could find, with power to force an entry wherever they suspected it was stored.[460]