Laws and theories

While laws and theories in science are related, they are still distinct from each other.

"One of the most resilient misconceptions about science is that laws are mature theories and, as such, laws are more valuable or believable than are theories. Laws and theories are related but individually important kinds of scientific knowledge and both should be considered valuable products of the scientific endeavor. Laws are generalizations or patterns in nature (such as Charles’s law), while theories are explanations for why such laws hold (such as the kinetic molecular theory of matter, which suggests that tiny particles behaving like billiard balls become more active as temperature rises)." McComas 2004, http://www.nsta.org/publications/news/story.aspx?id=49929). 

Stories where this aspect plays an important role are:

♦ Looking at the results of his chemical experiments, John Dalton notices that he has produced both, answers and (new) questions. He wonders, whether there is something like a superior principle.
Dalton and the atoms

♦ The formulation of the mechanical equivalent of heat can be taken as a crucial step towards the formulation of the principle of energy conservation. Joule demonstrated in a series of experiments that mechanical work (which he still called 'mechanical force') can be converted at a constant ratio into heat.
Joule and energy