03 December 2009

What is chemistry not?

On the 1st page of his classic textbook General Chemistry, Linus Pauling describes chemistry as "the science of substances—their structure*, their properties, and the reactions that change them into other substances". Then he compares the scope of chemistry with those of some other sciences, physics, astrophysics, biology and geology, and finally concedes that "[i]t is hard to draw a line between chemistry and other sciences".

It may actually be easier to decide if a given activity is not chemistry than it is to decide if it is chemistry. For example, if one is studying the influence of friction on the movement of a weight down a slope, that is not chemistry but physics; if one is studying the orbit of a comet around the sun, that is not chemistry but astronomy (and physics too); if one is studying the influence of a predator on a snail population, that is not chemistry but biology.

But if one is studying the influence of friction on the adhesive properties of a snail's slime by analyzing its chemical composition as a function of soil characteristics, is that chemistry, physics, biology or geology?

The oldest chemistry book I have is the English translation of Lothar Meyer's** Outlines of Theoretical Chemistry from 1892. According to Meyer, "Chemistry deals with the changes which affect the material nature of the substance. Chemistry, then, is the science which treats of matter and its changes."

Meyer's definition is essentially the same as that of Pauling.

One reason why we cannot pigeonhole every scientific activity into a category is that the fields of science do not and can not have clear-cut boundaries. The fields of science are not independent of each other. Instead, each and every field of science relies on others, derives support from them and, in return, supports them. I touched upon this notion briefly in this post.

*Shouldn't that be structures?
**According to the title page, Meyer was a professor of chemistry at the University of Tübingen.


Joel VanDerMeulen said...

Too true.

I think that structure would be correct in that sentence though, as it seems like he is referring to just a singular substance.


But he says "substances". So he should have said "their structures".

Joel VanDerMeulen said...

I see what you mean, but I still think the first half of the sentence refers to substances in general and after the hyphen he is talking about it as a singular item.