A Dictionary of Arts: Hematine.

A Dictionary of Arts, Manufactures, and Mines; containing A Clear Exposition of Their Principles and Practice

by Andrew Ure, M. D.;
F. R. S. M. G. S. Lond.: M. Acad. M. S. Philad.; S. PH. DOC. N. GERM. Ranow.; Mulh. Etc. Etc.

Illustrated with nearly fifteen hundred engravings on wood
Eleventh American, From The Last London Edition.
To which is appended, a Supplement of Recent Improvements to The Present Time.

New York: D Appleton & company, 200 Broadway. Philadelphia: George S. Appleton, 148 Chestnut St.
MDCCCXLVII

1847

HEMATINE is the name given by its discoverer Chevreul to a crystalline substance, of a pale pink color, and brilliant lustre when viewed in a lens, which he extracted from logwood, the Hæmatoxylon Campechianum of botanists. It is, in fact, the charasteristic principle of this dye-wood. To procure hematine, digest during a few hours ground logwood in water heated to a temperature of about 130° F.; filter the liquor, evaporateit to dryness by a steam bath, and put the extract in alcohol of 0.835 for a day. The filter anew, and after having inspissated the alcoholic solution by evaporation, pour into it a little water, evaporate gently again, and then leave it to itself in a cool place. In this way a considerable quantity of crystals of hematine will be obtained, which may be readily purified by washing with alcohol and drying.

When subjected to dry distillation in a retort, hematine affords all the usual products of vegetable bodies, along with a little ammonia; which proves the presence of azote. Boiling water dissolves it abundantly, and assumes an orange-red color, which passes into yellow by cooling, but becomes red again with heat. Sulphurous acid destroys the colour of solution of hematine. Potash and ammonia convert into a dark purple-red tint, the the pale solution of hematine; when these alkalis are added in large quantity, they make the colour violet blue, then brown-red, and lastly brown-yellow. By this time, the hematine has become decomposed, and cannot be restored to its pristine state by neutraliizing the alkalis with acids.

The waters of baryta, strontia, and lime exeche an analogous power of decomposition; but they eventually precipitate the changed colouring matter.

A red solution of hematine subjected to a current of sulphureted hydrogen becomes yellow; but it resumes its original hue when the sulphureted hydrogen is removed by a little potash.

The protoxide of lead, the protoxide of tin, the hydrate of peroxyde of iron, the hydrate of oxydes of copper and nickel, oxide of bismuth, combine with hematine, and colour it blue with more or less of a violet cast.

Hematine precipitates glue from its solution in reddish flocks. This substance has hitherto been employed in its pure state; but as it constitutes the active principle of logwood, it enters as an ingredient into all the colours made with that dye stuff.

These colours are principally violet and black. Chevreul has proposed hematine as an excellent test of acidity.