—___——. 
TALC. - 
plates, and in a figure resembling the frustra of 
two cones, applied base to base. Cleavage highly 
perfect; fracture not observable ; lustre pearly 
upon the faces of crystallization and of cleavage ; 
colour various shades of green, as blackish-green, 
leek-green, celandine-green, and apple-green ; 
streak similar to the colour; semi-transparent to 
translucent. It exhibits different colours, some- 
times in different directions; sectile in a high 
degree: thin lamine are easily flexible. It is 
one of the softest of all solid minerals. The 
massive kinds present a great variety of struc- 
ture. The composition varies from imperfect 
columnar to granular and impalpable. The indi- 
viduals are sometimes strongly coherent with 
each other, or flat, so as to give rise to an im- 
perfect slaty structure. The species tale has 
been subdivided into a great number of varieties 
_or sub-species, the most of which depend upon 
colours, composition, and foreign admixtures. 
The varieties of dark-green (leek-green and ce- 
landine-green) colours, inclining to brown, con- 
stitute the chlorite, which has been subdivided 
into common, slaty, and earthy chlorite. The first 
of these contains the granular or crystalline va- 
rieties; the second embraces those in which the 
individuals can scarcely be traced, and which ex- 
hibit a slaty texture ; the earthy chlorite consists 
of such as are but loosely coherent, or already in 
a state of loose, scaly particles. Immediately 
with those varieties of chlorite whose composition 
is impalpable, the green earth is connected. The 
species tale comprehends the varieties of pale- 
green, particularly apple-green, grey, and white 
varieties, and is divided, in popular language, 
into common, earthy, and indurated talc. Simple 
varieties are common talc ; also such compound 
ones in which cleavage is transformed into slaty 
structure, or such as consist of columnar particles 
of composition; earthy talc, or nacrite, consists 
of loose particles, or such as are but slightly co- 
hering ; and indurated tale refers to imperfect 
and coarse slaty varieties, in which this kind of 
structure is more the effect of composition than 
of imperfect cleavage. If this structure be suffi- 
ciently imperfect to become coarse and indis- 
tinctly granular, potstone, soapstone, lapis ollaris, 
or steatite, is formed, which, possessing the united 
properties of softness and tenacity, may be easily 
turned, and wrought into vessels. Four varieties 
of the present species, foliated talc, analyzed by 
Vauquelin, slaty chlorite, analyzed by Gruner, 
green earth, analyzed also by Vauquelin, and 
steatite by Klaproth, have yielded 
Silex, 62:00 29°50 52:00 59°50 
Magnesia, 27:00 21°39 6°00 30°50 
Oxide ofiron, 3:50 23°39 23:00 2°50 
~ Alumine, 150 15°62 7°00 0:00 
Water, 6:00 7:37 4-00 5°50 
Potash, 0:00 0:00 7 50 0:00 
Lime, 0:00. 1°50 0:00 0:00 
These analyses, as well as those of several other 
varieties of the species, show that our information 
TALLOW. 
respecting its chemical constitution is still very 
defective. Before the blow-pipe, some of them 
lose their colour, and are fused with difficulty ; 
others are changed into a black scoria; still 
others are infusible. Common talc, indurated 
tale, steatite, potstone, and slaty chlorite, consti- 
tute beds of themselves in primitive mountains. 
The latter often contains imbedded crystals of 
magnetic iron. Common chlorite is found in 
beds in rocks consisting chiefly of ores of iron 
and calcareous spar with augite. Other varieties, 
and among them the small scaly crystals of 
chlorite and earthy chlorite, occur in veins of 
various descriptions, and in the crystal caves of 
the Alps. Green earth occurs in amygdaloidal 
rocks, lining vesicular cavities. Tyrol, Salzburg, 
Switzerland, Sweden, Norway, Scotland, and New 
England abound in those varieties which by 
themselves form mountain masses. The soap- 
stone of Cornwall is impalpable in its composi- 
tion, nearly white, or sometimes mottled with 
green and purple: when first raised, it is so soft 
as to allow of being kneaded like dough; but, by 
exposure, loses a part of its moisture, and is then 
translucent on the edges, yields to the nail, and 
possesses an unctuous feel. A similar variety is 
met with in Wales. It is included in serpentine, 
and sometimes embraces veins of amianthus. 
The white varieties of steatite, or those that be- 
come so by calcination, are employed in the 
manufactory of the finest porcelain ; other varie- 
ties are said to be used in fulling. The Arabs, 
according to Shaw, use steatite in their baths, 
instead of soap; and it is confidently asserted 
that the inhabitants of New Caledonia either eat 
it alone, or mingle it with their food. Humboldt 
says, that the Itomaques, a savage race, inhabit- 
ing the banks of the Orinoco, are almost entirely 
supported, during three months of the year, by 
eating this variety of talc, which they first slight- 
ly bake, and then moisten with water. The va- 
rieties known under the name of potstone have 
been in use for the construction of a variety of 
utensils from time immemorial. It is particularly 
valuable as a fire-stone in furnaces, and is worked 
into plates in the fabrication of stoves. 
TALINUM. A genus of ornamental exotic 
plants of the purslane family. Nearly a dozen 
species, variously annual, biennial, herbaceous 
perennial, and subshrubby evergreen, mostly 
about a foot in height, and carrying purple, red, 
pink, or yellow flowers in the end of summer or 
early part of autumn, have been introduced to 
Britain: and about as many more are known. 
Most love a soil of peaty loam, and require to be 
propagated from seeds. 
TALLOW. The fat of suet freed from all 
membranous matter by melting and straining. 
It consists principally of stearin and elain, and 
yields by distillation a large portion of oleic and 
margaritic acids. Its ultimate constituents, ac- 
cording to Chevreul, are 78:996 per cent. of car- 
bon, 11°708 of hydrogen, and 0°304 of oxygen. 
