Analytical devices have been designed for a wide range of applications. Analyzing solutions and fluids by color comparison is one of the oldest, but qualitative. In the 1860s more sophisticated colorimeters were invented to compare colors more quantitatively. The blowpipe has been called the ‘stethoscope’ of the nineteenth century chemist. It was the most prominent laboratory apparatus from 1760 to 1860 and was still offered by manufacturers in the early to mid-1900s. With a laboratory spectroscope the elements in the flame of a burned sample cast a spectrum indicative of composition. Photometers and spectrophotometers measure light intensity within narrow wavebands to determine. A pocket-sized refractometer developed in the 1870s allows observation of refracted light to determine refractive index. Interferometers separate wave bands of light and other energy bands for a variety of laboratory applications. Chemists invented the actinometer or dosiometer to emit ultra-violet light around 1790 to measure the reaction rate of photochemically sensitive substances. Polarimeters came into use around 1800 to observe the interaction of an optically active substance with polarized light. A specialized polarimeter called the saccharimeter was widely used to determine the amount of sugar in solution. In the 1920s, due to the availability of photoelectric cells sensitive to the visible light spectrum, color comparison gave way to more quantitative instrumentation like the absorptiometer invented in 1936; the polarograph, one of the first automatic analytical devices, invented in 1922; and scintillometers to measure radiation.