CAS Numbers

chemicals. there's lots of them. you are made up of them, you eat them, you can't get away from them. take a guess now how many we have identified.
now check out CAS to see what their current count is.

as each chemical is published in a journal, patent, conference proceeding, it is assigned a number by the chemical abstracting service (CAS). they also do things like write an abstract for the article or whatever it is and extract some of the information into the database for searching. the number though is quite ingenious. it isn't a simple thing where they started at 1 and went up from there. first off, having a number is important because it is an easy way to id a molecule without the confusion of the IUPAC naming scheme. though the scheme is good it still requires some work to always get the same name. but the number also has a check sum built in so that errors in numbers are reduced. so this number is the one that you want to use when doing stuff like looking up government regulations, msds, and whatever. doesn't vary even when one of the many common chemical names is used rather than the IUPAC.

just in case you thought we were getting close to knowing a lot of things, they add about 4,000 new entries every day, yup day.

as a side note, there is currently a spat between ACS (american chemical society, who owns CAS) and NIH (national institute of health) because an NIH project has started to overlap with the CAS registry and ACS argues that the government shouldn't compete with the private sector. you can see ACS argument here. i think they are right to some degree. certainly if NIH makes this free information that used to be private sector there would be good argument for duplicating windows and making it free... after all it is just information.