It's a logo of a Thin Test Tube. The beaker has a dark outline and is white in the middle. The beaker is small and has a liquid inside just past halfway.
This Experiment icon is a responsive icon. This means that it's optimized for four resolutions, from tiny 16x16 until highly detailed 80x80. The style comes from the latest Microsoft Office
, which makes it perfect for any Windows applications, in particular, those with ribbon toolbar control. Unlike other icon packs that have merely hundreds of icons, this monster icon pack contains 15,900 icons, all in the same style and quality.