We allude to the process proposed and patented by Messrs. Parnell & Simpson, and about to be worked by the “Lancashire Alkali and Sulphur Company,” at Widnes.  We recently had the opportunity of inspecting fully the plant erected, and of having the method of procedure explained to us.  We look upon the new process as such a spirited attempt to turn the tide of a long and losing battle, and as so very interesting on its own merits, that an account of it in these pages will be thoroughly in place.

The main idea of the process is to combine the “Leblanc” and the “ammonia-soda” manufacture.  But in place of using caustic lime to decompose the ammonium chloride and get back the ammonia, the “alkali waste” spoken of above is employed, it being found that not only is the ammonia driven off, but that also the sulphur in the “waste” is obtained in a form allowing of its easy utilization, it and the ammonia combining to form ammonium sulphide, which passes over in gaseous form from the decomposing apparatus.  This ammonium sulphide is, as we shall see, quite as available for the working of the ammonia-soda manufacture as pure and simple ammonia, and all the sulphur can be obtained from it.

In outline the process is as follows:  We will suppose that a quantity of bicarbonate of sodium has been just precipitated from a brine solution, and we have the residual ammonium chloride to deal with.  This is decomposed by “alkali waste,” giving a final liquor of calcium chloride, which is run to waste, and a quantity of ammonium sulphide gas.  This latter is led at once into a solution of salt in water, till saturation takes place.  Into this liquor of brine and ammonium sulphide pure carbonic acid gas is now passed.  The ammonium sulphide is decomposed, pure sulphureted hydrogen gas is given off, which is conducted to a gas holder and stored, while ammonium bicarbonate is formed in the liquor, which brings about the conversion of the salt into bicarbonate of sodium, ready for removal and preparation for the market.

It will be observed that we printed the word pure in italics in speaking of the carbonic acid used.  This is one of the great points in the process, as in order that the sulphureted hydrogen gas obtained shall be concentrated and pure, only pure carbonic acid can be used in liberating it.  The apparatus employed in its preparation is perhaps the most ingenious part of the works, and well worthy of attention by others besides alkali makers.  The method is based on the fact that if dilute impure carbonic acid is passed into a solution of carbonate of sodium, the carbonic acid is absorbed, bicarbonate of sodium being formed, and the diluting gases passing away.

The bicarbonate of sodium on heating gives up the extra carbonic acid, which can be collected and stored pure, while the liquor passes back to simple carbonate of sodium, to be used over again as an absorbent.  This is not at all new in theory, of course, nor is this the first proposal to use it commercially; but it is claimed that this is the first successful working of it on a large scale.