A 



JOURNAL 



OF 



NATURAL PHILOSOPHY, CHEMISTRY, 



AND 



THE ARTS. 



AUGUST, 1803. 



ARTICLE I. 



On the Production of Sulphate of Magnefiafrom the AJhes of Pit- 

 Coal, with Remarks on the Effiorefcence of the fame Salt, ob- 

 ferved by Dr. Boftock. In a Letter from the Rev, William 

 Gregor. 



To Mr. NICHOLSON. 

 SIR, 



IN the number of your Philofophical Journal for December, "Effiorefcence 



1802*, I read a letter from Dr. Boftock of Liverpool, in fr " m a ?? es °/ u 

 ' . r p:t coal, which 



which he gives an account of an unexpected production of the afforded gypfurn 

 fulphateof magnefia; which brought to my recollection a facl, and fu jP ha <£ ofJ 

 which fell under my notice, about two years ago, and which • 

 may poffibly tend to throw fome light upon the phenomenon 

 obferved by your correspondent. — Having accidentally dis- 

 covered a faline cruft adhering to the wood-work of a frame on 

 which I fift my coal-afhes, for economical and agricultural pur- 

 pofes, I fcraped off a fufficient quantity of this fubftance with 

 a view of afcertaining its nature. I diflfolved it in diftilled 

 water, and Separated all impurities from it, by the filter. This 

 folution tried by the ufual tefts, gave indications of the prefence 

 of fulphuric acid, of lime, and of ibme other earth. I evapo- 

 rated the folution, and fome gypfum w r as Separated ; when this 

 fait ceafed to appear I poured off the fluid, which had affumed 



* Vol. HI. p. 288. 

 Vol.V. — August. Q a brownifh 



