650

HEMATINE.

balance the eflect of atmospheric changes, the iron stem which supports the regulator iterminated by a dial disc, round the shaft of the needle above h, fig. 549*; on turningthis needle the. stem below it turns, as well as a screw at its tinder end, which raises orlowers the leaden tube. In the first case, the heel falls, and opens the swing registerwhence a higher temperature is required to shut it, by the expansion of the tube.may thus obtain a regularly higher temperature. If, on the contrary, we raise the 4U ",by turning the needle in the other direction, the register presents a smaller opening, anshuts at a lower temperature; in this case, we obtain a regularly lower temperature,is therefore easy, says M. Bonnemain, to determine a priori the degree of temperaturebe given to the water circulating in the stove pipes. In order to facilitate the regulatn’of the apparatus, he graduated the disc dial, and inscribed upon its top and bottom 4words, Strong and Weak heat. See Thermostat, for another Heat-Regulator.

HEAVY SPAR, sulphate of Baryta, or Cawk ( Spath pesant, Fr.; Sc/iwefV’fg, ’Germ.), is an abundant mineral, which accompanies veins of ISad, silver, mercury, &but is often found, also, in large masses. Its color is usually white, or flesh-colored,occurs in many crystalline forms, of which the cleavage is a right rhomboidal prism-is met with also of a fibrous, radiated, and granular structure. Its spec. grav.from 4-1 to 4-6. It has a strong lustre, between the fatty and the vitreous. It ITie L t !.3 135° Wedgew. into a white opaque enamel. Its constituents are 65-63 baryta, and o .sulphuric acid. It is decomposed by calcination in contact with charcoal at a white « j (sinto sulphuret of baryta; from which all the baryta salts may be readily formed.chief employment in commerce is for adulterating white lead ; a purpose which it rft -J,serves on account of its density. Its presence here is easily detected by dilute nitricwhich dissolves the carbonate of lead, and leaves the heavy spar. It is also a use) ugredient in some kinds of pottery and glass. n ts

HECKLE (Seran, Fr.; Hechel , Germ.) is an implement for dissevering the fi laWof flax, and laying them in parallel stricks or tresses. See Flax . , ( j; a l-

HELIOTROPE is a variety of jaspar, mixed with chlorite, green earth, ax fg o0 i-lage; occasionally marked with blood-red points; whence its vulgar name ol

stone. . . . hsto nce ’

HEMATINE is the name given by its discoverer Chevreul to a crystalline sunof a pale pink color, and brilliant lustre when viewed in a lens, which he extracte^._ t j Clogwood, the hcematoxylon Campechianum of botanists. It is, in fact, the chara j 0 g-principle of this dye-wood. To procure hematine, digest during a few hours g r01 ’ jj towood in water heated to a temperature of about 130° F. ; filter the liquor, eva E? ia 0 fiU erdryness by a steam bath, and put the extract in alcohol of 0-835 for a day. The o ;t

anew, and after having inspissated the alcoholic solution by evaporation, P° ur j n ftiisa little water, evaporate gently again, and then leave it to itself in a cool place- ma y beway a considerable quantity of crystals of hematine will be obtained, whichreadily purified by washing with alcohol and drying. ducts

When subjected to dry distillation in a retort, hematine affords all the usual pro^_ gZO te.vegetable bodies, along with a little ammonia; which proves the presence passesBoiling water dissolves it abundantly, and assumes an orange-red color, w >■ s theinto yellow by cooling, but becomes red again with heat. Sulphurous acid des ^ t j n t,color of solution of hematine. Potash and ammonia convert into a dark P ur P 4be 'the pale solution of hematine; when these alkalis are added in large < l l '®Jf; in e, lbemake the color violet blue, then brown-red, and lastly brown-yellow. By 4 j- r|t .uti' ;i 'hematine has become decomposed, and cannot be restored to its pristine state )

izing the alkalis with acids.

The waters of baryta, strontia, and lime exercise an analogous powerbut they eventually precipitate the changed coloring matter.

of decomP osl

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becui

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Ltiniittcu l illwj itiutivi • « Atr£|fl U 4 * v ^

A red solution of hematine subjected, to a current of sulphnreted J«ovedb^yellow; but it resumes its original hue when the sulphureted hydrogen islittle potash. - ; roI1) the

The protoxyde of lead, the protoxyde of tin, the hydrate of peroxyde o einat ine, 8drate of oxydes of copper and nickel, oxyde of bismuth, combine withcolor it blue with more or less of a violet cast. . usance l ,aS 0 f

Hematine precipitates glue from its solution in reddish flocks. This su „ r jncipi ehitherto been employed in its pure state; but as it constitutes the act' «■logwood, it tenters as an ingredient into all the colors made with that dye ® ’ t j 0 e aS

These colors are principally violet and black. Chevreul has proposedexcellent test of acidity. jjkh-bro"' 11 P

HEMATITE (Fer Oligiste, Fr.; Rotheiseustein, Germ.) is a native red ‘‘ 0 f Cu« lboxyde of iron, consisting of oxygen 30-66 ; iron 60-34. It is the kidneyand, which is smelted at Ulverstone with charcoal, into excellent steel i ^ (lie canHEMP ( Chanvre , Fr.; Hanf, Germ.) is the fibrous rind of the b a

aft

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