March 16^th is Heinrich Kayser's birthday. Kayser was a German chemist who worked with German mathematician Carl Runge on identifying the spectra of the elements. Kayser noticed that the intensity of the spectral lines of many elements tended to group together in mathematical series. Both men worked together to develop a formula to predict the spacing of these lines.

Similar work was being done by Swedish physicist Johannes Rydberg. Rydberg's formula was much simpler, but only really fit the hydrogen spectrum. Kayser and Runge's formula was actually several formulas, depending on the element, and generally more accurate, but they never discovered an all inclusive formula to predict spectral lines.

One of the discoveries to come out of Kayser's work was the discovery of atmospheric helium. Helium had only been identified from the Sun's spectrum until it was found in the presence of uranium and the mineral cleveite. Kayser demonstrated Earth's atmosphere contained slight amounts of helium.

Kayser made many contributions to the study of spectroscopy, but much of his work searching for a mathematical formula to predict spectral lines would be set aside as the new study of quantum mechanics would enter the scientific arena. Find out what else occurred on this day in science history.

Radioactive material in movies and cartoons emits an eerie green glow. While not all radioactive materials glow green, or even glow at all, that glow is characteristic of uranium glass when it is exposed to ultraviolet radiation (black light). In normal light, uranium glass tends to have a yellowish color. Ultraviolet radiation gives it a bright green fluorescence.

Uranium glass emits enough radiation to buzz a Geiger counter, but it isn't considered dangerous, which is good since the object in this photo is a cake plate. Uranium glass is produced today for glassware and beads, but it isn't easy to find, basically because shipping radioactive materials isn't worth the hassle.

March 15^th is Josef Loschmidt's birthday. Loschmidt was an Austrian chemist who is best known for his close estimation of the size of air molecules. His value was nearly twice the actual size, but the correct magnitude. He also is known for the Loschmidt constant which sets the number of particles in a given volume of an idea gas as a constant. This value of 2.687 x 10²⁵ particles per cubic meter at STP is occasionally confused with Avogadro's number in textbooks.

Find out what else occurred on this day in science history.

The other day I was talking to someone about science education. This person felt a good time to introduce students to science was around the third grade. He felt science was a relatively difficult subject, so it was best to wait until students using logic and reasoning before teaching the subject. Of course, I disagreed. I think science is something even babies start learning when they first start to see the effects of their actions. Asking questions and learning how to answer them is something kids just naturally do, so you can introduce kids to science before they start kindergarten. There are lots of science projects you can do with preschool students that allow them to ask and answer questions and gain an appreciation for science. Get ideas for preschool science projects or, if you have a great idea already, post it to share your idea with others.