An introduction to practical chemistry : including analysis . Fig. 42. Sulphuretted Hydrogen Apparatus. 97. Blow some small bulbs. When it is required toblow a bulb at the end of a tube, the extremity shouldbe closed as in making a test-tube (89); if the glass istolerably thick, and the bulbto be blown not large, all that Kg. necessary is to heat theend for about half an inchas strongly as possible; and Athen, having removed itfrom the flame, and holdingit horizontally in the hands(Fig. 44), to blow air into it until the pressure forces the softened glass to expandwdiich it will do in th
An introduction to practical chemistry : including analysis . Fig. 42. Sulphuretted Hydrogen Apparatus. 97. Blow some small bulbs. When it is required toblow a bulb at the end of a tube, the extremity shouldbe closed as in making a test-tube (89); if the glass istolerably thick, and the bulbto be blown not large, all that Kg. necessary is to heat theend for about half an inchas strongly as possible; and Athen, having removed itfrom the flame, and holdingit horizontally in the hands(Fig. 44), to blow air into it until the pressure forces the softened glass to expandwdiich it will do in the formof a round bulb if the heat hasbeen properly applied, and thetube be kept constantly turnedround while in the hands. Thislatter precaution is absolutelynecessary, as the softened glasswould otherwise bend with itsown wTeight in one direction,thus destroying the proper formof the tube. 98. Seal a few tubes hermeti-cally at both ends. This is anoperation of very frequent use in the laboratory, as it Fig. 56 GLASS-WORKING. furnishes the most convenient and efficient means ofpreserving small specimens of many rare substances,especially such as are volatile. The tube is first sealed at one end, precisely as if it wereintended for a test-tube (89); the liquid or otherrs-45- substance for which it is designed is then intro-n duced, as soon as the tube is quite cold, care beingY taken that the upper part of the tube is not wet te< Ia*\ or soiled. The flame of the blowpipe is nowdirected to the portion of the tube a little abovethat intended for the sealed end, and when suffi-ciently soft it is drawn out to a capillary tube, andallowed to cool: it may afterwards be sealed byfusing the lower part of the capillary tube a (), by momentary contact with the flame. In this way seal a little sulphur in a tube w-ithoutmelting or volatilizing any of it, the sulphur beingwithin an inch and a half of the upper end. 99. Seal some water hermetically in a tube. Havingsealed the tu
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectchemistry, bookyear18
