It sometimes happens to men whose genius far transcends the level of their day, to be from that very circumstance neither understood nor believed by their contemporaries. Until the discoveries of modern chemistry, who would have given Sir Isaac Newton credit for his conjecture that the Diamond was an inflammable substance? The fact which Lemery sneers at, the reproduction of nitre in the earth, is established beyond contradiction by the authors quoted by Dr. Watson (Chem. Ess. v. 1. p. 318-321) and in Bowle’s account of the nitre earths in Spain, and in Andreossi’s memoir on the Saltpetre of Egypt. Though it is far from improbable that after lixiviation these earths may again become gradually impregnated with putrefying animal or vegetable matter to serve for the future crops of nitre. [38] Philosophical transactions v. 55 p. 232. [39] Dr. Priestley in his preliminary account of the discoveries and theories on respiration (Exp. on air v. 3 p. 356. abridged edit.) quotes Haller’s great work on Physiology. Haller quotes Mayow in three or four places; but it is no wonder the quotations did not strike Dr. Priestley with any curiosity to examine Mayow’s book, for Haller certainly did not understand his theory. For instance Lib. 8. § 13. Nitrum aereum. Si ad verum sensum nitri aerei hypothesis revocata fuisset parum utique ab eà differt quam novissimè proposuimus. Nitrum quidem ipsum incautiosius olim Physiologi in aere obvolitare scripserunt, et ex pluvià et nive colligi; idemque passim ex rupibus efflorescere (Sprat ex Henshaw p. 264 major cal. hum.) exque plantis et stercoribus educi (Fludd Niewentydt, 563-4. Mayow de nitro aereo. Lower de Corde c. 3. Thurston 52. 53. Besse Analyse tom 1 et en lettre en reponse à M. Helvet. 114.) id nitrum aiunt in pulmonibus ad sanguinem venire, et ab eo ruborem illum elegantem, et fermentationem (Mayow, Thurston penult. ess. T. 3 p. 265) et calorem sanguinis accedere aut vicissim sanguinem condensari. Certainly the id nitrum, is not Mayow’s. M. Rosel seems first to have ascertained the existence of nitre in plants. A late experiment of Dr. Priestley’s, of which he gave an account in a letter to Dr. Wistar, seems to make it probable that there may be nitre in snow.