In this state the instrument remained, until Mr. Goldsworthy Gurney applied himself to its improvement, and after numerous experiments, which are highly interesting, and are fully detailed in his published lectures, he succeeded in producing an instrument unattended with the slightest danger in its use, and admirably adapted both for scientific investigation, and for various operations in the arts. The annexed engraving is a representation of the instrument. A is the safety chamber; B a water trough, through which the gas is made to pass from the gasometer D by the cock C, through a tube which reaches to the bottom of the water trough; is a cock fitted into the neck of the same, from which it is thrown out should an explosion take place on the surface of the water. F is a gauge, to indicate the necessary height of the column of water in the trough. G is a transferring bladder, which is made to screw and unscrew to and from the stop-cock H, for the purpose of supplying the gasometer with gases, which may be charged and recharged at pleasure, by an assistant, during its action, so as to keep up the most intense flame for any length of time.

A valve is placed between the gasometer and the transferring bladder, which prevents the return of the gas. l l is a light wooden or stiff pasteboard cap, which combines sufficient strength with great lightness, so that in case an explosion of the gasometer should happen, it is merely thrown a short height into the air, by the force breaking the strings which connect the cap to the press board. To these strings are attached small wires, which pass through the table of the instrument, as at L, into the press-board below, where they are secured; this press-board is kept in a horizontal position by the stand, so that when the requisite pressure is given to it, the cap l l is brought to bear equally on the gasometer D. The gasometer bladder (or silk bag) is tied to a piece of bladder, which screws into a long tube laid into and across the table, which permits it to be unscrewed at pleasure from the body of the instrument, and immersed in water when it requires softening, affording also the means of fixing on another bladder, if any accident should render it necessary. The stop-cock of the charging bladder G is fixed to one end of the tube just described, and the stop-cock of the water trough on the other end.

To operate with this instrument, pressure by the hand is applied to the press-board, which draws down the cap l l on the gasometer D, and forces the gas which it contains through the stop-cock C, and through the water tube and safety chamber A, to the jet at the end, where it is burned. When the pressure on the press-board is too slight, or when the hand is taken off, the flame returns into the safety chamber, and is extinguished. When it is required to suspend the operation, the hand need only be taken off the pressing board, the water in the trough acts as a self-acting valve in preventing the escape of gas from the instrument, and saves the necessity of turning the stop-cock. A silk tube is attached to the end of the tube before described, in the water trough, which prevents the splashing of the water, sometimes occasioned by unskilful management We omitted to state that the safety chamber A is filled with numerous discs of very fine wire gauze closely packed, and should the flame be driven in, which will sometimes happen, it will not enter the bag or reservoir D, but will explode above the surface of the water in the chamber B, merely driving out the cork. An improvement has, however, been since introduced in the construction of the safety chamber, by Mr. Wilkinson, of Ludgate-hill, by which the retrogade motion of the flame appears to be effectually prevented, and a much larger jet may be employed than heretofore with perfect safety. This improvement consists in filling the chamber A with alternate layers of wire gauze and of asbestos, previously beaten with a mallet, and pulled out to resemble floss silk. Mr. Wilkinson received from the Society of Arts a silver medal, for his communication on the subject, and we understand that Mr. Hemming has recently made some further improvements in the construction of the instrument. We must here advert to the wonderful effects produced by the oxy-hydrogen blow pipe, which almost instantaneously reduces the hardest and most refractory substances. Gun flints are instantly fused by it, and formed into a transparent glass; china melts into a perfect crystal. All kinds of porcelain are readily fused, previously assuming a beautiful crystallized appearance. Rock crystal is quickly melted, giving out a beautiful light. Emerald, sapphire, topaz, and all the other precious stones, melt before it into transparent glassy substances. Barytes, strontian, lime, and alumina, exhibit very striking and beautiful phenomena. Magnesia fuses into hard granular particles, which will scratch glass.

The metals, even platina, are all quickly fused by it; and all descriptions of stones, slates, and minerals, are melted, sublimed, or volatilized, by its all-subduing power.

Blow Pipe 191Blow Pipe 192