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Se&ion gtb. 

 Vitriol of Iron. 



loo parts of this vitriol newly cryflallized contain by my de- 

 termination 28 calx of iron in the ftate of osthiops, equal nearly 

 22 of metallic iron, 26 real vitriolic acid, 38 water of cryftal- 

 lization, and 8 water of compofition, that is which adheres to 

 the acid. This determination I lately confirmed ; for from a fo- 

 lution of 100 grains of this vitriol decompofed by muriated 

 barytes I obtained 77,25 of ignited barofelenite, which at the 

 rate of 33,3 per cent, contained 25,747 of real vitriolic acid. 



Hence 100 parts vitriol of iron calcined to rednefs contain 

 41,93 of real acid, and i2,g of water ; but the calx of iron will 

 weigh more than 45, as it attrads oxygen during the calcina- 

 tion. 



The water of compofition is for the moft part expelled with 

 the acid during diftillation. Then 22 grains metallic ironfhould 

 afford 100 grains of cryflallized vitriol : and 100 grains of the 

 bell iron would give 454,54 of vitriol. 



Th e vitriol above examined was of a full grajs green colour. I have 

 met with another which is of a pale fea green colour, and con- 

 tains much lefs acid, for 1 00 grains of it treated as above afforded 

 only 56,7 of barofelenite, and confequently contained but 18,99 



of real acid. 



F f 2 ScBion 



