Blowpipe practice; an outline of blowpipe manipulation and analysis, with original tables for the determination of all known minerals . ks), swell or curl up onexposure to the blowpipe, and then fuse quietly; but some, as prehnite, meltwith more or less bubbling. (h) The test-fragment may remain unchanged. Example, quartz, and variousother infusible minerals. (2) Treatment in the Flask or Bulb-Tube (The Water Test).—Mineralsare frequently subjected to a kind of distillatory process by ignitionin small glass tubes closed at one end. These tubes are of two generalkinds. One kind has the form of
Blowpipe practice; an outline of blowpipe manipulation and analysis, with original tables for the determination of all known minerals . ks), swell or curl up onexposure to the blowpipe, and then fuse quietly; but some, as prehnite, meltwith more or less bubbling. (h) The test-fragment may remain unchanged. Example, quartz, and variousother infusible minerals. (2) Treatment in the Flask or Bulb-Tube (The Water Test).—Mineralsare frequently subjected to a kind of distillatory process by ignitionin small glass tubes closed at one end. These tubes are of two generalkinds. One kind has the form of a small flask, and is commonly knownasa bulb-tube. Where it cannot be procured, a small-sized test-tube may supply its place. It is used principally in testing mineralsfor water. Many minerals contain a considerable amount of water, orthe elements of water, in some unknown physical condition. Gypsum,for example, yields nearly 21 per cent, of water. As the presence ofthis substance is very easily ascertained, the water test is frequentlyresorted to, in practice, for the formation of determinative groups, or 10 BLOWPIPE Fig. 9. separation of hydrous from anhydrous minerals. The operation isthus performed. The glass is first warmed gently over the flame ofa small spirit-lamp to ensure the absence of moisture, and is then setaside for a few moments to cool. This effected, a piece of the sub-stance under examination, of about the size of a small pea, is placedin it, and ignited over the spirit-lamp—asshewn in the annexed figure—the tubebeing held in a slightly inclined water be present in the mineral, a thinfilm, condensing rapidly into little drops,will be deposited on the neck or upper partof the tube. As soon as the moisturebegins to shew itself, the tube must bebrought into a more or less horizontalposition, otherwise a fracture may beoccasioned by the water flowing down andcoming in contact with the hot part of theglass. The neutral, acid, or alkali
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishertorontocoppclark
