C 47 3 



This fait is' found in large quantities in Afia 

 and Africa, and in their mineral waters, and in the 

 waters of fome parts of Germany; its cryftals are 

 commonly rhomboidal, extremely foluble in wa-, 

 ter, but when expofed to the air, fall into pow- 

 der, it is detected in water by 



a. Paper ftained with the tin&ure of litmus 

 is changed to a blue colour. 



Tintlure of litmus is prepared by infujing litmus, 

 powdered, for a Jhort time, in diftilled water ; with 

 this the paper is ftained. 



b. Paper ftained with the tinclure of bra* 

 zil wood loofes its red, and is changed to a vio- 

 let. 



The tinclure of Brazil wood is made in the fame 

 manner as the tintlure of litmus, but hot water 

 fhould here be employed. 



c. Paper, ftained yellow by an infufion of tur- 

 meric, is changed to a brown colour. 



The infufion of turmeric fJjould be made with hot 

 water. 



d. Upon adding a folution of corrofive fub- 

 limate mercury to this water, a white precipitate 

 is produced ; if the alkali be in large propor- 

 tion, this precipitate will be an orange colour. 

 In this inftance the alkali unites with muriatic 

 acid of the corrofive fublimate, and the mercury 

 is precipitated. 



e. Add a fmall quantity of Epfom fait to this 

 water, it will diffolve, and no precipitation will be 

 perceived, but give it a very littie warmth, and 

 immediately white flakes will be feperated: here 

 the mineral alkali combines with the vitriolic 

 acid of the Epfom fait, and detaches the mag- 

 nefia its other conftituent part, which aifo unites 



to 



