Important part of the basic formation of laboratory is the training in the handling of blowing and welding of glass in order to could compound simple equipment and repair the one that is damaged. We are going to see the techniques that we considered be more useful to the alchemist.

The glass is a liquid on cooled, lacking of macrocrystaline structure, without point of defined coalition, softening inside intervals of temperatures more or less long.

The tube of ordinary glass, the Kimble and their equivalent, sodium- calcium silicates softens between 400 and 500º C, one could blow and work satisfactorily by means of a torch with air and gas, whose flame is blue and lightly yellowish in the tip. Using lighters potent meeker type or Fischer could be worked tube of 6 mm.

The white ordinary glass has a high coefficient of expansion, for what in order to avoid smashing should heat initially with a yellow flame and they during the manipulation will avoid the very high temperatures, because it could vitrify.

Finished the blown, the tube should cool down slowly and flame with a yellow-grizzly flame, rotating it continually so that remain covered with an uniform layer of soot, because otherwise the tensions developed during the cooler will shatter it.

The Pyrex glass Not. 774, that it is a boron silicate and their equivalent like Kimex, Kimax and Durex soften to 819oC and their coefficients of expansion are very low. In order to manipulate a torch them are used with entering for gas, oxygen and air or for gas and oxygen. The appropriate mixture one could obtain adjusting, initially, the gas entrances and air so that they give a moderate flame and not luminous and then feeding the necessary oxygen in order to obtain a thin bluish cone, (initially noisy).

If only there is gas and oxygen, light the gas and then goes to you adding the oxygen. The hottest part corresponds to the tip of the blue cone, whose diameter and longitude depend on the size of the hole of the burner and the composition of the gassy mixture.

The tubes of Pyrex glass, until they of 10 mm of diameter could be introduced temperature of the torch in the flame of discharge without they smash. Material of old diameter should preheat with a flame of gas-air, or gas and little oxygen.

The operation of tempering is important particularly with big pieces, requiring care and practice, especially with the ordinary glass; because the temperature to that it begins the temperate is very near to that of softening. The fused portion should rotate continually in a soft flame, orange, until begin to put on red, then gradually is gone diminishing the temperature for what is gone managing the material in the coldest parts of the flame and lowering the temperature of this slowly.

Finally cover the piece with the soot of a yellowish flame; with what a surface is obtained that cool down very slowly. For big pieces ovens are used for temperate.

From the tube that is going to be the main part closes an end with asbestos, or a plug of float surrounded of asbestos. With a fine flame warm a small point in the center of the tube and blown smoothly in order to obtain a small bladder of minor diameter that the tube that is been going to weld there. The bladder warms, carefully in the tip and blown a globe of thin walls, which is exploded with a file and the glass of the thin wall is eliminated rasping with a cloth of wire until leaving a small lateral tube which is welded with the second tube (previous close for an end). Then blowing and warming it give the form adapted to the points of union.

One could manufacture small and small balloon flasks allude to them blowing Pyrex tube. For this close the end of a tube, heating the close end strongly so that thicken the wall, then are blown a little and t heat again until augment and pick up, then blow a little again. This manipulation is repeated until have accumulated the necessary amount of glass in order to obtain a bulb of the wanted diameter.

Then warms the thick end until soften, placing the tube in horizontal position and making it rotate slowly while the bulb is blown to the wanted diameter. In order to correct the tendency of the bulb to shrink in a side, it is necessary to rotate that side quickly and blow smoothly.

In order to obtain a bulb in any another part of the tube, closing an end, hot the section where you want to form the bulb, begin to join glass in that point pressing the two sides of the tube simultaneously until have the necessary glass.

Apply to the whole section an open flame, making it rotate, until have a single thick wall, then hot the whole mass of glass and begin to blow maintaining the tube in rotation at the same time, until obtain a bulb of homogeneous diameter and regular walls.

The body of the cooler it is a long tube with round bottom. The end of the interior tube that is been going to weld is enlarged previous, and inserted in the external tube. In order to maintain it in the appropriate position introduces a tube, which is sustained for a plug of float. The external piece tour in horizontal position, going a thin flame toward the bottom of the external tube and to the point of contact between this and the tip enlarged of the interior tube. The two pieces melt and are formed a small ring. Then go the flame to the center of the bottom of the external tube, the glass softens and is blown a globe. The glass of the globe is eliminated. The tube is covered. Immediately after closing, and before the welded ring cools down, a tube is welded, previous prepared, as soon as has ended this manipulation, a point in the lateral wall is blown, previous heated with a thin flame. The formed globe is exploded and is welded a lateral tube to the cooler. Then the inferior part, inclusive the welded ring, is tempered carefully.

The plug takes off and this end closes and is rounded. Finally the tube bends in right angle, giving the cooler of finger.

They in similar form are built the wells for thermometers, the closings of mercury and similar apparatuses.

The apparatus should clean carefully in the point t are starry, then are begun to heat smoothly and carefully, elevating the temperature of the flame slowly until obtain a blue flame. If the starry position doesn't close spontaneously, blow smoothly, so that upon expanding the soft portion welded the starry part. It in some cases is necessary use a bar of the same glass of 1-2 mm of diameter, which melts in order to unite the borders of the starry part.

When the piece is a big flask or similar recipient, suits begin to heat with much care and direct the flame to an area moved away to about three centimeters of the starry portion, with which if upon increasing the temperature of the flame increases the zone shattered in the hot portion, interrupt the rupture, creating a point in which one could begin the weld.

In the case of soft glass or Kimble, these methods are practically useless.