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BLOWING, an agitation of the air by means of a pair of bel-lows, the mouth, &c. Butchers hare a very pernicious custom ofblowing meat, to deceive the buyer. The sudden change of vealand lamb in particular may, in some degree, be attributed to thiscause. It is also a common practice to blow poultry, and all sortsof f.sh, except those of the shell kind. As the venders of provi-sions, who are guilty of such disgusting practices, may at the sametime be infected with the most loathsome diseases, the articlesthus polluted should be rejected as being unfit for consumption.Indeed, the pernicious tendency of blowing meat is obvious, andought therefore to be discouraged by every class of purchasers,while it claims the serious and vigorous interference of the publicmagistrates.
Blowing, [exsujHatio,'] a ceremony in the ancient adminis-tration of baptism, whereby the catechumen, upon rehearsing therenunciation, blew three blasts with his mouth, to signify that herejected the devil. Something like this is still retained in the Rus-sian church.
Blowing, in gardening, the action of flowers, wherein- they Iopen and display their leaves.
Blowing of Glass, one of the methods of forming variouskinds of works in the glass-manufacture. It is performed by dip-ping the point of an iron blowing-pipe into melted glass, and blow- jmg through it with the mouth, according to the circumstances of ,the glass to be blown. See Glass. !
Blowing of Tin denotes the melting its ore, after being first !burnt, to destroy the mundic. I
BLOW -PIPL, or BLOW1NG-PIPE, ahollow lube, used by ;several artificers ; as enamellers, glass-makers, jewellers, &c. itis a wind-instrument for the purpose of increasing the heat of acandle or lamp, as common bellows are employed for raising thetemperature of a fire or furnace. The blow-pipe is of great usein practical chemistry. The late Sir Torbern Bergman observedthat this instrument is extremely useful to chemists, as manyexperiments are daily- neglected, either because they requirefqrnaces and a large apparatus of vessels; from the want of timeto examine them in the ordinary way ; or from the quantity re-quired in the common way for examination, when the mattermay be too scarce or too dear. In all these cases the blow-pipemay be advantageously used; as, 1. Most of the experimentswhich can be performed in the large way may also be done withthe blow-pipe. 2. The experiments which in the large way re-quire mauy hours, may in this method be finished in a few mi-nutes ; and, 3. The smallest particle is sufficient. The onlydefect is, that the proportions cannot be determined with anyprecision ; ami therefore where the experiments can be tried ona large scale, it is always preferred. “ But the first inquiry totie made,” says Sir Torbern , ‘‘is, what a substance contains,not how much ; and I have learned by the experience of manyyears, that these trials in small quantities suggest the propermethods of instituting experiments in large. These experimentsbesides have some advantage over those conducted in crucibles,viz. we can sec all the phenomena from beginning to end, whichwonderfully illustrates the series of operations and their causes.There arc various constructions of this instrument: the most sim-ple is merely a glass or metal tube, ending in a cavity as fine as asmall wire, through which the air is blown on the flame of a can-dle; a more complete instrument is Mr. Cronstedt ’s blow-pipe,which is composed of two parts; and this for the facility bothof making, carrying it along, and cleaning it in the inside whennecessary. The two parts are represented separate, (tig. 10 and11, Plate XXVIII.) The figure of the instrument, when theseare put together, may be easily conceived. The globe a, (fig. 11,)is hoilow^ and made on purpose to condense the vapours, whichare always in the blow-pipe when it has been used some time: ifthis globe was not there, the vapours would go directly withthe wind out into the flame, and thereby cool the assay. Thelrole in the small end h, through which the wind comes out,ought not to be larger than the size of the finest wire. This hole,when it happens to be stopped, is to be cleared by means of afine wire c, represented in fig. 10, fastened round tire blow-pipe,and afterwards drawn through a small hole at e, made in the ringf, to keep it more steady. Bergman’s blow-pipe consists of threeparts, which may be occasionally joined: An handle, (fig. 12,)terminating in a truncated conical apex a a, which may, bytwisting, be so adapted to the aperture h, (fig. 13,) as to shut it
more closely than can be done by a screw. It was an improve-ment of former chemists to have a hollow ball on the tube, tocollect the moisture of the breath, which, if suffered to accumu-late, would greatly diminish the intensity of the flame. Insteadof the hollow bulb in the tube, Bergman devised the little box,(fig. 13,) formed of an elliptical plate, so bended through the cen-tre that the opposite sides become parallel, ami are joined roundby a plate equal in breadth to c c. Such a box collects themoisture of the breath as well as the sphere, and is besides at-tended with the advantage of a compressed figure and smallercircumference. The aperture b is somewhat conical, and hol-lowed out of the solid piece : and has no margin turned inward,
1 lest the efflux of tire fluid colb'cted after long bluwing, or thecleansing of the internal parts, should in any degree be pre-vented. The tube, (fig. 14,) is very small, and its shorter conicalend c e exactly listed to the aperture f, so that no air can escapeH except through the orifice g. Many of those lubes should be| provided with orifices of diffiirent diameters, to be applied on| different occasions: the orifice g itself ought tube smooth andcircular, otherwise the cone of flame hereafter to be mentionedwill be divided. The bands h h, (fig. 12,) and i i, (fig. 14,) pre-. vent the conical apices, aa, ee, from being thrust in too far, andj also serve another purpose; for when these apices are, by re-| peated attrition, at last so much diminished as to fall out spon-[ taneously, by filing away a little of the bands, they may again; be made tight. Another blow-pipe in general use consists of liveI parts: the mouth-piece, plain tube, bulb, curved tube, and nut.j It is made of brass except the mouth-piece, which is ivory, andfits the tube so as to be air-tight; they consist of two hemispheresscrewed into each other, 't he hydrostatic blow-pipe is an inge-nious invention by Mr. Robert Hare, jun. of Philadelphia . Toa well-seasoned cask he adapted a very ingenious apparatus,acting by means of hydrostatic pressure within the cake. Bytliis means lie could produce the greatest regularity of stream andintensity of heat, and apply liis instrument with the utmost con-venieucy, using at pleasure the atmospheric air, or any of thegasses, two species of which maybe used at once, kora fulldescription 9ee Tilioch’s Philosophical Magazine, Vol. 14. page240, &c. Melograni’s blow-pipe also depends on the action ofwater, but is confined in its use to atmospheric air. It is com-posed of two globes admitting the water to run from one toanother as the sand in as hour-glass. By means of the flowingof the water a stream of air is forced through a side-tube fixedat right angles to the nexus of the globes : when the upper globeis empty it may be reversed, and the running continues as be-fore. Tims in fig. 15, Plate XXVIII, let the lower globe behalf-filled with water and inverted, the orifice being closed by avalve or stop-cock ; then the water in A, running through thetube C into B, will consequently force a constant stream ofatmospheric air into the tube D, and thence into the side-tubeE, at the mouth of which the candle is placed. The greatestdifficulty in the use of the blow-pipe is the supplying it with aconstant stream of air by the breatli ; for to such as are unaccus-tomed to it, it appears a contradiction to think ot blowing astream of air out by the mouth, at the same time that we aredrawing it in by the nostrils to supply the necessary functions ofrespiration. An uninterrupted stieum of air, however, is abso-lutely necessary ; and “ to succeed in this operation,” says Berg-man, “ without inconvenience, some labour and practice arenecessary.” The whole art, however, consists in this, that whilethe air is inspired through the nostrils, that which is contained indie mouth be forced out through the tube by the compressionof tlie cheeks. Frequent trials will establish tiie habit; so that-acontinual stream of air may be supplied for a quarter of an houror more, without any other inconvenience than the lassitude ofthe lips compressing the tube. A very great and obvious im-provement, however, is still suggested by Dr. Bcrkenhout, viz.to apply tlie tube to the w ind-hag of a hag-pipe ; which beingfirst blown full, may easily be kept so; and being compressedby the arm, will produce a blast either strong or weak as wehave a mind. It will still be a farther improvement to supply thisbag by means of a small bellows instead ot blowing into it withthe mouth; for thus the air will he more free from moisture,and also fitter for tlie support of flame, in other respects; as thereis always a considerable quantity of fixed air produced at everyrespiration, which, according to that, quantity, must unfit tlie air