BLOOD. (Sang, Fr.; Blut, Germ.) The liquid which circulates in the arteries and veins of animals; bright red in the former and purple in the latter, among all the tribes whose temperature is considerably higher than that of the atmosphere. It consists 1. of a colourless transparent solution of several substances in water; and 2. of red, undissolved particles diffused through that solution. Its specific gravity varies with the nature and health of the animal; being from 1·0527 to 1·0570 at 60° F. It has a saline sub-nauseous taste, and a smell peculiar to each animal. When fresh drawn from the vessels, it rapidly coagulates into a gelatinous mass, called the clot, cruor, or crassamentum, from which after some time, a pale yellow fluid, passing into yellowish green, oozes forth, called the serum. If the warm blood be stirred with a bundle of twigs, as it flows from the veins, the fibrine concretes, and forms long fibres and knots, while it retains its usual appearance in other respects. The clot contains fibrine and colouring matter in various proportions. Berzelius found in 100 parts of the dried clot of blood, 35 parts of fibrine, 58 of colouring matter; 1·3 of carbonate of soda; 4 of an animal matter soluble in water, along with some salts and fat. The specific gravity of the serum varies from 1·027 to 1·029. It forms about three fourths of the weight of the blood, has an alkaline reaction, coagulates at 167° F. into a gelatinous mass, and has for its leading constituent albumen to the amount of 8 per cent. besides fat, potash, soda, and salts of these bases. Blood does not seem to contain any gelatine.
The red colouring matter called hematine, may be obtained from the cruor by washing with cold water and filtering.
Blood was at one time largely employed for clarifying syrup, but it is very sparingly used by the sugar refiners in Great Britain of the present day. It may be dried by evaporation at a heat of 130° or 140°, and in this state has been transported to the colonies for purifying cane juice. It is an ingredient in certain adhesive cements, coarse pigments for protecting walls from the weather, for making animal charcoal in the Prussian blue works, and by an after process, a decolouring carbon. It is used in some Turkey red dye-works. Blood is a powerful manure.
BLOWING MACHINE. See [Iron], [Metallurgy], [Ventilation].
BLOWPIPE. (Chalumeau, Fr.; Lothröhre, Germ.) Jewellers, mineralogists, chemists, enamellers, &c. make frequent use of a tube, usually bent near the end, terminated with a finely pointed nozzle, for blowing through the flame of a lamp, candle, or gas-jet, and producing thereby a small conical flame possessing a very intense heat. Modifications of blow pipes are made with jets of hydrogen, oxygen, or the two gases mixed in due proportions.
BLUE DYES. (Teint, Germ. See [Enamel].) The materials employed for this purpose are [indigo], [Prussian blue], [logwood], bilberry, (vaccinium myrtillus,) elder berries, (sambucus nigra,) mulberries, privet berries, (ligustrum vulgare,) and some other berries whose juice becomes blue by the addition of a small portion of alkali, or of the salts of copper. For dyeing with the first three articles, see them in their alphabetical places. I shall here describe the other or minor blue dyes.
To dye blue with such berries as the above, we boil one pound of them in water, adding one ounce of alum, of copperas, and of blue vitriol, to the decoction, or in their stead equal parts of verdegris and tartar, and pass the stuffs a sufficient time through the liquor. When an iron mordant alone is employed, a steel blue tint is obtained; and when a tin one, a blue with a violet cast. The privet berries which have been employed as sap colours by the card painters, may be extensively used in the dyeing of silk. The berries of the African night-shade (solanum guineense) have been of late years considerably applied to silk on the continent in producing various shades of blue, violet, red, brown, &c. but particularly violet. With alkalis and acids these berries have the same habitudes as bilberries; the former turning them green, the latter red. They usually come from Italy compressed in a dry cake, and are infused in hot water. The infusion is merely filtered, and then employed without any mordant, for dyeing silk, being kept at a warm temperature by surrounding the bath vessel with hot water. The goods must be winced for six hours through it in order to be saturated with colour; then they are to be rinsed in running water and dried. One pound of silk requires a pound and a half of the berry cake. In the residuary bath, other tints of blue may be given. Sometimes the dyed silk is finished by running it through a weak alum water. A colour approaching to indigo in permanence, but which differs from it in being soluble in alkalis, though incapable of similar disoxidizement, is the gardenia genipa and aculeata of South America whose colourless juice becomes dark blue with contact of air; and dyes stuffs, the skin, and nails, of an unchangeable deep blue colour, but the juice must be applied in the colourless state.
BLUE PIGMENTS. Several metallic compounds possess a blue colour; especially those of iron, cobalt, and molybdenum. The metallic pigments, little if at all employed, but which may be found useful in particular cases, are the molybdate of mercury, the hydro-sulphuret of tungsten, the prussiate of tungsten, the molybdate of tin, the oxide of copper darkened with ammonia, the silicate of copper, and a fine violet colour formed from manganese and molybdenum. The blues of vegetable origin, in common use, are indigo, litmus, and blue cakes. The blue pigments of a metallic nature found in commerce are the following: Prussian blue; mountain blue, a carbonate of copper mixed with more or less earthy matter; Bremen blue, or verditer, a greenish blue colour obtained from copper mixed with chalk or lime; iron blue, phosphate of iron, little employed; cobalt blue, a colour obtained by calcining a salt of cobalt with alumina or oxide of tin; smalt, a glass coloured with cobalt and ground to a fine powder; charcoal blue, a deep shade obtained by triturating carbonized vine stalks with an equal weight of potash in a crucible till the mixture ceases to swell, then pouring it upon a slab, putting it into water and saturating the alkali with sulphuric acid. The liquor becomes blue, and lets fall a dark blue precipitate, which becomes of a brilliant blue colour when heated.
Molybdenum blue is a combination of this metal, and oxide of tin or phosphate of lime. It is employed both as a paint, and an enamel colour. A blue may also be obtained by putting into molybdic acid, (made by digesting sulphuret of molybdenum with nitric acid,) some filings of tin, and a little muriatic acid. The tin deoxidizes the molybdic acid to a certain degree, and converts it into the molybdous, which when evaporated and heated with alumina recently precipitated, forms this blue pigment. [Ultramarine] is a beautiful blue pigment, which see.