Seventific Intelligence. 203 
18. Acidulous sulphate of iron, (from a correspondent.)—In Vol. 
XV, at p. 238, is a notice by Prof. Eaton, of native sulphuric acid ; 
a substance possessing the same properties, is said to be often found 
in. the vicinity of beds of sulphuret of iron. “1 have, (says our cor- 
respondent,) several times analyzed a compound from Strafford, Vt. 
whose characters, so far as observed, correspond with that noticed by 
Prof. E.. Sulphate of protoxide of iron, decomposed by air and light, 
ultimately retains but one Aalf the quantity of peroxide of iron, which 
our bi-persulphate does. Very dilute sulphuric acid chars vegetable 
substances when exposed to the sun’s rays; crystallized sulphate of 
zinc, is even quite an active acidule under such circumstances.” 
19. Roxbury Laboratory, (near Boston.)\—The company incor- 
porated under the name of the Roxbury, Color and Chemical, Co. 
employ Mr. A. A. Hayes, to superintend the manufacture of sulphu- 
ric, nitric and muriatic acids ; sulphates of copper, zinc, and potash ; 
alum, white vitriol, ferro-prussiate of potash, and Prussian blue, in its 
different forms. Verditer blue and green, French green, rose and 
Dutch pinks, slip yellow, and fig blue. Some of the processes are 
original, and the quantities are such as the market warrants. 
19. Correction.—By a letter from the Rev. Isaac Bird, dated 
Malta, March 24, 1829, we learn with regret, that the note on page 
377, Vol. XV. of this Journal, is erroneously referred, by the aster- 
isk, to the late Mr. Fisk, and that the reference should have been to 
the end of line 3d, on the top of the page, which would fix the erit- 
icism where it belongs, upon an author always indeed animated and 
interesting but somewhat remarkable for “bold speculations.”" 
Mr. Fisk was not an author, and never wrote or published any 
thing on the subject referred to in the note.—Ed. 
21. Iron Mines.—Extract of a letter to the Editor, dated New 
York, August, 1829.—On a late visit to the Monroe Iron Works, in 
Orange county, in this state, I rode over to the iron mines of the 
Messrs. Townsend, distant about five miles, in a south westerly direc- 
tion, from the extensive iron works of Messrs. Blackwell and Mc- 
Farlan. The larger of the two mines has been worked for upwards 
of seventy years, and the vein of iron, which is a rich oxide, seems to 
be inexhaustible. It appears to be about four feet in the narrowest part, 
running in a nearly horizontal line at about ten feet below the surface, 
and is very easily worked. The proprietors have, within ten or 
