Results of Laboratory Session #1
(The pairs of numbers in the density columns are the results of the two labs.)

SOLIDS			LIQUIDS
Item	Density (g/cc)		Item	Density (g/cc)
coal (C)	1.18, 1.08		cold tapwater	1.00, 0.99
aluminum (Al)	3.14, 2.69		warm saltwater	1.08, 0.96
lead (Pb)	11, 11.8		cold saltwater	1.05, 1.05
glass (SiO2)	2.15, 2.42		isopropyl alcohol	0.91, 0.92

Another result was that when the liquids were layered they went from top to bottom this way: isopropyl alcohol, cold tapwater (red), warm saltwater, cold saltwater (blue).

Now let¹s turn to writing the report. Before using the above numbers in the table, first delete those, if any, that are not reasonable. One basis for reasonableness is, for example, that you consider which type of data is more reliable - the actual measurements of the density, or where one of the liquids floats in relation to the others. Another basis regarding the solids is that you compare your results with those of other people. In the ³CRC Handbook of Chemistry and Physics² are tables of pure chemicals and their densities. Dr. Faile has a copy of this huge book (and so do I in my office across the hall from his).

One final result of the needle demonstration I failed to remember to do for the Tuesday group. I asked the Monday people which was denser - steel or water. They said steel. I proceeded to show them how it would also sink in the water as they thought it should. Then I demonstrated how a needle could be made to float on water if carefully placed on the surface. (Tueday people, you might try this in your rooms.)

My question was: how could this be that in one moment the needle would sink and in another it would float? This will become part of a later lab. But in the meantime I will show you some other related magic tricks!