A Treatise on Calico Printing, Of Earths.

A Treatise on Calico Printing, VOL. I-II
Printed for C. O'Brien, Bookseller, Islington, and fold by Bew, Paternoster-row: Richardson, Royal Exchange: Murray, Fleet-Street: And the Booksellers of Manchester, Glasgow, Dublin, &c.
1792Earths are either ponderous; calcareous (Lime) magnesia; argillaceous (Clay;)or silicious (Crystal) They are characterized by remaining unaltered in a red heat, and of those five above mentioned no one has been yet able to decompose or transunite one into another.

Ponderous earth forms with vitrolic acid, ponderous spar, and is not soluble in one thousand times its own weight of boiling water.

Calcareous earth saturated with vitriolic acid forms gypsum, known by the property it has of forming, after a flight burning, a hard mass with water.

Magnesia saturated with vitriolic-acid; forms what is called Epsom salt.

Pure argillaceous earth with vitriolic acid forms an allum.

The abevesour hinds may be called absvbent earths but the last has the least claim.

Silicious earth is not affected by vitriolic acid, it is however dissolved by that of spar, the dia mond excepted, neither is the diamond changed by the greatest heat, if not exposed to the air.