70 
ON BICHROMATE OF LIME, ETC. 
writing ink, produced by the said process, to a sufficient 
consistence, and then rubbing up the same in oil as afore- 
said. 
Black Printing Ink, JVb. 2. 
And, 12th, I manufacture a black printing ink by boihng 
chips of logwood (for which an extract of logwood may be 
substituted,) or other dye woods containing colouring 
matter and tannin, along with as much of a protosalt or 
persalt of iron, or copper, or other precipitate of tannin, as 
will be equal to about twice the weight of the tannin con- 
tained in the wood or extract employed ; whereby I obtain 
a black or blueivsh black precipitate, the blueness of which 
I diminish, as may be required, by the addition of bichro- 
mate of potash, more or less. I finally rub up the whole 
in oil as aforesaid, adding a small quantity of the lamp- 
black or other black colouring matter, ordinarily employed 
in the manufacture of black printing inks. — Pharm. Journ. 
from Mechanics^ Magazine. 
ART. XIX.— ON A NEW AND ECONOMICAL PROCESS FOR 
MANUFACTURING THE BICHROMATE OF POTASH, 
CHROMATES OF LEAD AND BICHROMATE OF LIME. 
By V. A. Jacquelain. 
1. Chalk and chrome ore, previously reduced to a very 
fine state of division, are intimately mixed in barrels revol- 
ving upon their large axis. It is especially requisite that 
the ore should be finely pulverized and passed through a 
very fine sieve. 
