Gas Balance c. 4th quarter 19th century Friedrich LUX, Germany Wood, glass, brass, steel Knife edge balance used to weigh and determine the specific gravity of gas 24” long x 11” wide x 15” high The purpose of this instrument is to determine the specific gravity of a gas being weighed and therefore the composition of the gas. It has an inlet and outlet gas valve. An enclosed brass ball holds the gas and is attached to a long arm balance assembly that rests on two agate-style bearings when in use. There is an external lifter adjusted by a thumb screw to raise or lower the balance assembly on the bearings. The front two-thirds of the arm is graduated from 0.0 to 1.0 in twenty equal lines. There is a rider band on the arm. At the end of the arm is a pointer which reads a silvered scale from +0.25 to -0.25, reading in tenths. There is an adjustable vertical and horizontal balance weight at the top of the arm. The gas is piped from the inlet valve under the case and up a small brass tube through the back one-third of the long arm balance assembly into the gas bowl. It travels through the bowl and back to the outlet valve. In-use air is first run through the bowl until it is filled with only air. Then the long balance arm is adjusted with the rider band until the pointer reads “0” on the silver scale. The location of the rider is read - let’s say, “0.5”. Then the gas is pumped into the brass ball for five minutes or so to make sure all the air has been evacuated. Once this is done the pointer’s silvered scale is read - let’s say, “0.15”. The sum of the rider reading and the pointer reading equals specific gravity: 0.5 + 0.15 = 0.65. The outer dimensions are 24” long x 11” wide x 15” high. This instrument is in excellent condition and includes the lock key. An engraved nameplate says “Friedrich LUX Gaswage №110 LUDWIGSHAFEN@/Rh”. Circa 1890 - 1900. Antique Scientific Instrument