30 OP THE ORIGIN OF CHEMISTRY; 



Strabo fpcaks of two placed beyond Momcm- 

 phis, where nitre is produced. The Egyptian 

 nitre, according to Pliny*, was dark coloured, 

 and hard like a Hone; and the proccfs of mak- 

 ing it fimilar to that of fait, except that the fea 

 was let into the fait pans, while the Nile only 

 entered thofefor nitre. As the Nile retired they 

 became dry, but were kept moift tor forty days, 

 "by being fprinkled with the nitrous folution. If 

 rain fell, they diminiflicd a proportional quanti- 

 ty of the Nile, and removed the nitre from the 

 pits as fooi i as it began to thicken, loll it Humid 

 be uj'.ain diflblved. In this oily rtatc they ap- 

 plied it as a remedy for the fcab in animals. 

 When laid by in large mattes it becomes hard. 

 They reckon the lighteft part of nitre, and con- 

 fequemly the frothy part, the beft; but the 

 roarfe dregs are ferviceab'le in dying purple and 

 all other colours. -The Memphitic nitre was 

 foul in its concretions; from whence the ftony 

 iuaiFes of which vafes were formed, and fome- 

 t hue's reduced to a coal by means of ignition 

 \vith fulphur. The aphronitrum, or fcum of ni- 

 tre, w:is brought in veflels covered with pitch, 

 letl it ihould clillblve by contact with the air. 

 Nitre was adulterated with lime, which was ca 

 lily difcovcred by the tafle; the genuine melt- 

 ed readily in the mouth, but the fpurious was 



extremely 



the flower of kit, fcems to apply properly to tlie fairer* of 

 fal ammoniac. 



* L. x\xi. c. iu. 



