210 USE OF GKEEN VITRIOL 



Dr. Pearfon's Experiments, Ohfervations, and Remarks on the 

 Subjlance called Salt of Peat, or Duft. 



Dr. Pearfon's 1. It is a blackifh gray, coarfe, and rather heavy powder, 



chemical examl- Has no fmell ; taftes ftrongly ftvptic; readily diffolves in the 



nation of fait of ,-,,,. r r .* - 



peat or duft. mouth ; did not deuquelce on expolure to the air. 



2. Diflblves in fou* times its weight of water of the tem- 

 perature of fixty degrees of Fahrenheit, and in twice its weight 

 of boiling hot water, giving a pale green coloured folution, 

 with a trifling fediment, which is infoluble in muriatic acid. 



3. To the folution (2.) I added a little liquid pruffiate of 

 vegetable alkali in a perfectly neutral ftate, which occaiioned 

 immediately a mofl abundant precipitation of pruffiate of 

 iron; and this teft was added gradually, till no further precipi- 

 tation took place. 



4. Into the decanted and filtrated fluid (3) was poured li- 

 quid cauftic volatile alkali, but without inducing any change. 



5. Into the fame fluid (3) was poured liquid carbonate of 

 vegetable alkali, which produced a fcarcely perceivable cloudy 

 appearance. 



6. Into the folution (3) was dropped the aqueous folution 

 of muriate of baryt, which occafioned immediately a milky 

 appearance. 



7. To the folution (3) I added the oxalic acid, and turbid- 

 nefs enfued. 



8. A little of the powdery fubflanee, called the fait of peat, 

 with concentrated fulphuric acid, produced no emiffion of 

 fumes, nor fmell. 



9. The folution (2) with muriate of baryt, immediately 

 grew thick and white as cream. 



10. The folution (2) with carbonate of potafh, depofited a 

 very copious greenith fediment; and the fame effect enfued 

 with cauftic volatile alkali. 



11. The folution (2) with oxalic acid, gave inflantly a very 

 turbid bluitb green precipitation. 



The preceding experiments manifefled that the peat fait con- 

 fifts of fulphate of iron, vulgarly called green vitriol of iron, 

 mixed with a very minute proportion of filicious earth, and of 

 lime united either to fulphuric acid, or to carbonic acid. But 

 the pretence of the earths magnefia and argil!; the uncom- 



bined 



