Until the commencement of series research in the middle of the 19th century, accurate weighing had to be done on the conventional swan neckor box end beam scales.In the University of Edinburgh, in 1755 Dr.Black used precision balance to conduct experiments which laid the foundation for modern quantitative chemistry. Figure shows the balance with the glass case removed. The beam is light and well designed. The bearings for the end knife-edges are planes delicately balanced and a relieving device raises the central knife edge from its bearings.
The triple beam balance is an instrument used to measure mass very precisely.Such devices typically have a reading error of ±0.05 grams. Its name refers to its three beams, where the middle beam is the largest, the far beam of medium size and the front beam the smallest. The difference in size of the beams indicates the difference in weights and reading scale that each beam measures. Typically, the reading scale of the middle beam reads in 100 gram increments, the far beam in 10 gram increments, and the front beam can read from 0 to 10 grams.The triple beam balance can be used to measure mass directly from the objects, find mass by difference for liquid and measure out substances.