Sodium pyrosulphate

Substances which are insoluble or only partially soluble in acids are brought into solution by fusion with the appropriate reagent. The most commonly used fusion reagents, or fluxes as they are called, are anhydrous sodium carbonate, either alone or, less frequently, mixed with potassium nitrate or sodium peroxide potassium pyrosulphate, or sodium pyrosulphate sodium peroxide sodium hydroxide or potassium hydroxide. Anhydrous lithium metaborate has found favour as a flux, especially for materials containing silica 12 when the resulting fused mass is dissolved in dilute acids, no separation of silica takes place as it does when a sodium carbonate melt is similarly treated. Other advantages claimed for lithium metaborate are the following. 

Sodium pyrosulphate, or sodium anhydro-sulphate. NasS207... 

Pyrosulphuryl Chloride, S205C12.—Rose first prepared this substance in 1838 by the interaction of sulphur trioxide and sulphur monochloride.4 It is formed by the action of many chlorides on sulphur trioxide sulphur monochloride,4 thionyl chloride,5 silicon tetrachloride,6 phosphorus pentachloride,7 phosphorus oxychloride,8 sodium chloride 9 and carbon tetrachloride 10 all yield the desired product when treated with sulphur trioxide at a suitable temperature. With sodium chloride a mixture of pyrosulphufyl chloride and sodium pyrosulphate is obtained, whilst with the exception of carbon tetrachloride and phosphorus pentachloride, which are converted into oxychlorides, all the remaining chlorides are changed into oxides ... 

SOaH group may be introduced in certain cases by the use of potassium trihydrogen disulphate, KH SO, or sodium pyrosulphate, Na2S207. 

Sodium pyrosulphate, Na2S207.—The pyrosulphate is produced by the action of sulphur dioxide on sodium sulphate, or by heating the primary sulphate ... 

Sodium hydro-pyrosulphate, or sodium hydrogen anhydro-sulpliate Sodium pyrosulphate, or sodium anhydro-sulphate, ... 

As is known, the pyrosulphates of alkalies, such as sodiun pyrosulphate, can be manufactured according to various methods. The cheapest way of making sodium pyrosulphate, for example, which is a very cheap raw material, is to heat sodium bisulphate in vacuo. The pyrosulphates can also be made by combining sulphur trioxide with a sulphate, such as sodium sulphate. Similarly the chlorosulphonates of alkalies can be made by combining sulphur trioxide with a chloride, such as sodium chloride. 

Alcohol vapour may be passed over sodium pyrosulphate heatecj to about 150° C. If reduced pressure is maintained in the apparatus tl ie diethyl sulphate will distill off as fast as formed, together with any excess of alcohol. The diethyl sulphate can be isolated in any known or suitable way. 

The sodium pyrosulphate may he used in the proportion of aboui two molecules to two molecules of alcohol or of about one molecule of tlx pyrosulphate to one molecule of ether. I do not confine myself t( employing the materials in these proportions but may use the alcohol o ether in excess, or otherwise vary the proportions. 

P. WoUer observed that sulphur dioxide does not reduce the oxide at a red-heat and L. and P. Wohler and W. Pliiddemann studied its catalytic action in the oxidation of sulphur dioxide. H. P. Cady and R. Taft found the oxide to be insoluble in liquid sulphur dioxide, while chromic oxide which has been calcined at a high temp, does not dissolve in sulphuric acid. J. Weise said that if a trace of chromic acid be present, chromic oxide passes into soln. T. Sabalitschka and F. Bull said that fusion with sodium pyrosulphate is the best way to bring ignited chromic oxide into soln. 

Porcelain crucibles are very frequently utilised for igniting precipitates and heating small quantities of solids because of their cheapness and their ability to withstand high temperatures without appreciable change. Some reactions, such as fusion with sodium carbonate or other alkaline substances, and also evaporations with hydrofluoric acid, cannot be carried out in porcelain crucibles owing to the resultant chemical attack. A slight attack of the porcelain also takes place with pyrosulphate fusions. 

Naturally, the flux employed will depend upon the nature of the insoluble substance. Thus acidic materials are attacked by basic fluxes (carbonates, hydroxides, metaborates), whilst basic materials are attacked by acidic fluxes (pyroborates, pyrosulphates, and acid fluorides). In some instances an oxidising medium is useful, in which case sodium peroxide or sodium carbonate mixed with sodium peroxide or potassium nitrate may be used. The vessel in which fusion is effected must be carefully chosen platinum crucibles are employed for... 

Fusion with a flux such as sodium hydroxide, potassium bifluoride potassium pyrosulphate has been used extensively in the water industry. 

When heated strongly, for instance above 450° C., the pyrosulphates undergo decomposition into sulphur trioxide and the corresponding normal sulphate. The sodium salt, which melts at 400-9° C.,8 exhibits appreciable dissociation at about 460° C. In contact with moist air or... 

This pyrosulphate (or disulphate) is run off in a fluid condition into iron pans, where it solidifies and is used for the manufacture of normal sodium sulphate by heating with salt, NaCl, in mechanical sulphate furnaces. Part of this nitre cake, as the product is called, is now converted into sodium sulphide, Na.jS. 

Prussian blue, 81 soluble, 82 Pseudoctimene, nitrated, 102 Pulping gun cotton, 95, 96 Pyrites, burnt, use as catalyst, 29 Pyrosulphate, sodium, 18... 

Fusion with sodium fluoride-potassium pyrosulphate-concentrated sulphuric acid. Digestion with fuming sulphuric acid-ammonium sulphateconcentrated nitric acid. 

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