AND LOWER EGYPT. 321 



salt, and, finally, to a small degree of vitriolic 

 tartar. In the magazines two sorts are to be dis- 

 tinguished ; tie common and the sullan'ie : this an- 

 swers to the word royal, by which are designated in 

 France several commodities of a superior quality. 

 This W/tf //-natron is whiter, better crystallized, 

 and more pure than the common ; it is conse- 

 quently more powerful, and, in the use of it, a 

 smaller quantity is employed. 



This mineral alkali possesses the same proper- 

 ties with the vegetable alkali, or salt-wort ; but it 

 possesses them in a superior degree of virtue. Its 

 principal use is for the bleaching of thread and 

 cloth. The following is the method which I have 

 seen pursued at Rossetta. The skeins of thread 

 are laid in a large copper built in mason-work ; a 

 layer of natron is placed upon them : afterwards 

 cold water is poured on it, in a sufficient quantity 

 to soak the thread and the natron. They are thus 

 left altogether for the space of three days, at the 

 end of which the thread is drawn out, and sus- 

 pended on sticks placed over the kettle. When 

 it is drained, a fire is kindled under the copper, 

 and the water in which the thread had been steep- 

 ed with the natron is made to boil, after having 

 some lime added to it. The thread is dipped in 

 it, and washed several times, stirring it through 

 this hot lye, without leaving it there. It is im- 



vol. 1. y mediately 



