A college text-book of chemistry . forevaporating is represented inFig. 2. After the liquid has evapo-Vta. 2. rated and the substance in the evaporatmg-dish is dry, examine it and carefully compare itsproperties with those of the substance which was put into thetest-tube. Its structure will be found not to present the regulari-ties noticed in the original substance. It is much softer, dissolvesin water, melts when heated in a hard-glass tube. It does not giveoff a gas when treated with hydrochloric acid. When exposed tothe air it soon becomes moist, and after a time liquid. The experi-ment sho
A college text-book of chemistry . forevaporating is represented inFig. 2. After the liquid has evapo-Vta. 2. rated and the substance in the evaporatmg-dish is dry, examine it and carefully compare itsproperties with those of the substance which was put into thetest-tube. Its structure will be found not to present the regulari-ties noticed in the original substance. It is much softer, dissolvesin water, melts when heated in a hard-glass tube. It does not giveoff a gas when treated with hydrochloric acid. When exposed tothe air it soon becomes moist, and after a time liquid. The experi-ment shows that when hydrochloric acid acts upon calc-spar ormarble the latter at least loses its own properties. It might beshown that some of the hydrochloric acid also loses its place of the two we get a new substance with entirely differ-ent properties. The two substances have acted chemically uponeach other and produced a chemical compound. In this case itwas only necessary to bring the substances in contact in order to. VARIOUS EXAMPLES OF CHEMICAL ACTION. 31 cause them to act chemically upon each other. It was not neces-sary to heat them, as it was in the case of the iron and sulphur. 1 Experiment 10.—Bring together in a test-tube a few smallpieces of copper and some moderately dilute nitric acid. In ashort time action begins. The upper part of the tube becomesfilled with a dark, reddish-brown gas which has a disagreeablesmell. Do not inhale it, as when taken into the lungs it producesbad effects. The solution becomes colored dark blue, and thecopper disappears. Examine this solution, as in Experiment 9,and see what has been formed. What are the properties of thesubstance found after evaporation of the liquid ? Is it colored ?Is it soluble in water ? Does it change when heated in a tube ?Is it hard or soft ? Does it in any way suggest the copper with \ which you started ? A Experiment 11.—Try the action of dilute sulphuric acid on alittle zinc in a test-tube. A
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectchemistry, bookyear19
