Mercury trough

On account of its characteristic odour, sulphur dioxide was early recognised as a product of the combustion of sulphur, although the gas was not isolated until Priestley in 1775, by means of his mercury trough, collected it from the interaction of mercury and sulphuric acid.1 Lavoisier almost immediately afterwards showed that the new substance was a compound of sulphur and oxygen inferior to sulphuric acid in oxygen content. 

Few would have attempted such a colossal task Think of the time and the conditions under which he worked. In the reminiscences of his famous pupil, Woehler, is a description of the room m which Berzelius labored. The laboratory consisted of two ordinary rooms with the very simplest arrangements there were neither furnaces nor hoods, neither water system nor gas. Against the walls stood some closets with the chemicals, in the middle the mercury trough and the blast lamp table. Beside this was the sink consisting of a stone water holder with a stopcock and a pot standing under it. In the kitchen close by, in which Anna prepared the food, stood a small heating furnace. The chemicals he had to use in his analyses were often either unpurchasable or too impure to be used for accurate results... 

Apparatus Eudiometer, mercury, mercury trough, ammonia gas generator and drying apparatus, induction coil, battery, meter stick, barometer, and thermometer. 

The barometer-tube method was improved by Ramsay and Youngs (pig. 3.VIII J). They used a comparison vacuous barometer surrounded by a water-jacket at constant temperature. The barometer tube to contain the liquid was first filled with mercury which was boiled in a water-pump vacuum. Some liquid was introduced and boiled in vacuum to free it from air. More mercury was added and the tube inverted in the mercury trough. The open end had, as shown, a narrower side tube, the wider tube being sealed below. The liquid passed to the top of the mercury.. The tube was heated in a vapour jacket, the liquid being boiled in a bulb at the side under a constant air pressure maintained in a large reservoir. The difference in mercury levels in the two tubes was read, and the level in the vapour tube corrected for temperature and the weight of the small column of liquid above it. 

Gases are collected over the pneumatic trough, by displacement of air or over the mercurial trough. 

Wohler found Berzelius s laboratory to consist of two rooms, without furnaces, flues, water, or gas. In one room were two pine tables, at one of which Berzelius worked and at the other his pupil. On the walls were a few cupboards with some reagents, but most of the chemicals had to be prepared. In the middle of the room was a mercury trough and a blowpipe table. The water supply was a stoneware vessel with a tap, with a tub below. In the other room were the balances and other instruments. A furnace and sandbath were in the kitchen, where Anna cooked the meals. Berzelius said that in 1808 there was only one platinum crucible in Sweden, which belonged to Hisinger it was loaned to Berzelius but was too heavy for his balance, but in 1811 he was regularly using one. ... 

The combustion method used by Berzelius was an improvement of Gay-Lussac and Thenard s. A mixture of an organic substance (or a lead salt of it) with potassium chlorate and sodium chloride to moderate the reaction was put into a glass tube closed at one end, wrapped in sheet-iron, and supported in a sloping position on a brick B (Fig. 19). The drawn-out end of the tube was connected by rubber joints with a small bulb AC to collect the water formed and a straight calcium chloride tube CD, terminated by a delivery tube passing to a bell-jar in a mercury trough. After the combustion a small bulb containing caustic potash and covered with thin leather was passed into the bell-jar... 

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