It should instead to generally be pressed so that the gap with the bulb will make an air-restricted seal against the mouth with the pipet. Take note in this article that Dr. Reilly has squeezed the bulb prior to he pressed it from the mouth on the pipet. Quantity pipettes https://types-of-pipettes-used-in30494.bloggactivo.com/28951696/the-best-side-of-types-of-pipette-and-their-uses