What is the definition of qualitative knowledge?

There are basically two kinds of observations that scientists make, which are described as qualitative and quantitative. A qualitative observation gives you a general description. For example, a particular substance might be observed to be a liquid, blue in color, in a bottle. Quantitative observation involves measurement. For the same substance you might discover that it weighs 1.098 kg, that it has a temperature of 23o C, and by pouring it into a graduated cylinder, you could determine that it has a volume of 1.3 liters, etc. Qualitative observations don't involve numbers, and quantitative observations do.