Measuring Mass in the Laboratory

The analytical balance is the common piece of equipment in the scientific laboratory. These highly precise instruments can measure down to ten thousandths or even hundred thousandths of a gram. The triple beam balance is a type of scale that uses counterweights on a three rider beams to counterbalance the sample in the pan. On the other hand, modern analytical balances use a complex system of electronic sensors to accurately mass a substance. The analytical balance is so sensitive that it often has a draft shield to prevent air currents from interfering with the measurement. When weighing, a weigh boat or weigh paper is used to hold the substance being weighed and protect the weighing pan. Before weighing a substance, analytical balances are tarred to subtract the weigh boat or weigh paper and re-zero the scale. Tarring refers to setting the scale back to read zero and allows for a substance to be accurately weighed. Aside from weighing chemical substances, analytical balances are used to animals or insects, and centrifuge tubes in ultracentrifugation experiments.