INDEX,

Method os combining its Line with

difficultly fusible metals-519

with platina-520

Ca’eination, increase of weight produced

in iron-551

in mineral platina-4,9

in a mixture os platina and tin 5 5Sin a mixture of gold and tin — 618Conjecture on the cause of the increase-461

Carat weights explained —-llj

Casts from medals, a matter for taking3 54

Cement which quickly hardens in water 64

Cement alien, purification of gold by 90,1 54Imperfection of the process— 155, 472Its use-1;;

Chalk, black, description and uses — 325found in England--324

Charcoal, as a pigment-33;

Its differences from foot black 3 57, 376

Crayons- 355

Experiments of the differences of diffe-rent coals --336

Vegetable, how distinguished from that

of bones --33-8, 377

Stains glass yellow by baking — 629Tinges glass in fusion yellow, reddish,

&c. — — — — —> — — 628

Clay, its contraction in drying-258

Its purity judged from its contraction

Coalpits, means of mewing air in them— — -- 273> 636

Cobalt, a ready method of distinguishing

from other minerals-343

Stones tinged by f lution of its metallic

part- 437

Vitrification of its metallic part — 586

Cochineal, infusion turned blackish by so-lution of platina-— — 479

Coins, gold, use of all -y in them — 114Fineness of those of different count; ies

-116, 117

/allowance of fineness in the Englishcoinage-_—-->b>

Copper melted with gold — — — 82, 8jPromotes the fusion of gold — — 82Melted with platina in different pro-portions — — — —- —. — 529Hirdened and made less disposed to

tarnish —---330, 531

Always incompact after melting, 530Produces a gold colour with tin — 624Stones stained by solutions of it — 440Dissolved by vitriol of iron — — 390

Precipitation of gold by it-109

Glass coloured with it, on being bakedwith white earth, gave a red tinge tothe earth-— — —-247

Cotton, stained black — --433

purple- 97-434

red-434

Cr<w«,airimbibed by water passing through

it- 291

Quantity of the water influenced by thesucking pipe being open or close 292

Crayons, Charcoal-— —. — 3 3 33

Differences of coals for crayons —.337Excellence of that of willow — 337

Black lead- 328

Different forts, how made — 328

Best way of obtaining good ones 329

Crucibles, method of preparing so as tostand sulphureous mixtures — 136

Black lead, their advantages-67

whether hurtful to gold-616

made into portable lurnaces-2

Cupels, method of preparing-129

Cupellation, furnace for— >—-12

Pii ciple of the operation-89

Method o r conducting the process 131

Proportion of lead --132

Marks for regulating the sire ,32, 133Gold not made quite pure by cupella-

Efflorefcence of silver in the cupel—260

Cuttle, bane, its use for taking impressions,kz.~. -333

Cuttlefisti ink — —-— — 334

D.

Diamond, its foil — —- — — — 321one said to be black — — 321, 637

Distillation,