. Chemistry: general, medical, and pharmaceutical, including the chemistry of the U. S. Pharmacopia. A manual on the general principles of the science, and their applications in medicine and pharmacy. ck copper oxide in coarse powder. 200 or 300grammes of this material are heated in a crucible to low red-ness for a short time to expel every trace of moisture—thentransferred to store-tubes (Fig. 85) resembling test-tubes, halfa metre long and having a slightly narrowed mouth, the tube CARBON, HYDROGEN, OXYGEN, NITROGEN. 689 being held in a cloth to protect the hand while the hot oxideis being d
. Chemistry: general, medical, and pharmaceutical, including the chemistry of the U. S. Pharmacopia. A manual on the general principles of the science, and their applications in medicine and pharmacy. ck copper oxide in coarse powder. 200 or 300grammes of this material are heated in a crucible to low red-ness for a short time to expel every trace of moisture—thentransferred to store-tubes (Fig. 85) resembling test-tubes, halfa metre long and having a slightly narrowed mouth, the tube CARBON, HYDROGEN, OXYGEN, NITROGEN. 689 being held in a cloth to protect the hand while the hot oxideis being directly introduced into the mouth of the tube by ascooping motion. As soon as the well-corked tube is cool, theoxide is poured, portion by portion, into a similar tube (the Fig. 85. combustion-tube), but somewhat longer, drawn out to a quill(bent upward nearly to a right angle) at one end and not con-stricted at the mouth. Two such tubes are readily made bysoftening in the blowpipe-flame two or three centimetres of thecentral part of a tube about a metre long, and drawing thehalves of the tube apart as shown in the following engraving(Fig. 86). The tubes are separated by melting the glass in. the middle of the quilled portion. A few decigrammes offused potassium chlorate should first be dropped into the 10 or 15 centimetres of oxide have been poured in, abouta decigramme of the substance to be analyzed is dropped downthe tube, then a few grammes of oxide, then another deci-gramme of substance, then more oxide, until 3 or 4 decigrammesof the body under examination have been added. The 15 or20 centimetres of alternate layers are next thoroughly mixedby a long copper wire having a short helix : more oxide isintroduced, the wire cleansed by twisting the helix about inthe pure oxide, and a plug of dried asbestos finally placed onthe top of the oxide at about five centimetres from the mouthof the tube; the tube is then securely corked and set substance operated
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