The sodium sulphate is afterwards fluxed with calcium carbonate and coal, and a mixture is thus obtained from which sodium carbonate can be extracted by exhausting it with water.
????\,: v, sulphate of soda (salt-cake) with about the same weight of crushed limestone and half its weight of coal, until the materials are fluxed and a reaction has taken place, the principal phase of which is expressed by the equation Na2S04+CaC03+2C= 2CO 2 +Na 2 CO 3 -+-CaS.
After about threequarters of an hour the substances are so far fluxed or softened that the reaction now sets in fully, as shown by the copious escape of gas.
The inside shape of the producer is such that the upper, less hot portion cannot get stopped, as it widens out towards the bottom; the lower, hotter portion, where the ashes are already fluxed, is contracted to a slit a, through which the air ascends.
Bronze is improved in quality and strength when fluxed with phosphorus.