Teachers Handbook to Accompany Foundations of Chemistry

consist of the incombustible residue from the coal. These products are of no use, and the ashes and smoke are difficult to dispose of without making a nuisance. Hence the furnace is surely not run to obtain these substances. 10. After a mason slakes lime, he allows the product to cool before he uses it mixed with sand and hair as mortar. In this reaction it is the material product and not the heat that is sought. CHAPTER II MIXTURES AND CHEMICAL SUBSTANCES Pages 15-19 To illustrate the separation of a mechanical mixture it may be well to have the pupils separate the constituents of black gunpowder, with which they are already familiar. To do this treat a pinch of powder with a few c.c. of carbon disulphide, filter into a watch glass, and allow the disulphide to evaporate. This will give sulphur by itself. Next use a few c.c. of water with the solid residue (first allow all the carbon disulphide to evaporate) and again filter on to a clean watch glass. On evaporating the water, they will now obtain saltpeter. The insoluble charcoal of the gunpowder will be left on the filter paper. As gunpowder is so excellently blended, few pupils would suspect at first that it is a mixture, and yet the simple physical means of separation above outlined will serve to show its character. Answers to Questions on Chapter II Page 19 1. Matter is that of which any physical object or body is composed, whatever its form or condition, whether gaseous like air, liquid ...