tons of Stassfurt salts, for which the farmers paid more than $20,000,000.  Then a declaration of American independence—­the German embargo of 1915—­cut us off from Stassfurt and for five years we had to rely upon our own resources.  We have seen how Germany—­shut off from Chile—­solved the nitrogen problem for her fields and munition plants.  It was not so easy for us—­shut off from Germany—­to solve the potash problem.

There is no more lack of potash in the rocks than there is of nitrogen in the air, but the nitrogen is free and has only to be caught and combined, while the potash is shut up in a granite prison from which it is hard to get it free.  It is not the percentage in the soil but the percentage in the soil water that counts.  A farmer with his potash locked up in silicates is like the merchant who has left the key of his safe at home in his other trousers.  He may be solvent, but he cannot meet a sight draft.  It is only solvent potash that passes current.

In the days of our grandfathers we had not only national independence but household independence.  Every homestead had its own potash plant and soap factory.  The frugal housewife dumped the maple wood ashes of the fireplace into a hollow log set up on end in the backyard.  Water poured over the ashes leached out the lye, which drained into a bucket beneath.  This gave her a solution of pearl ash or potassium carbonate whose concentration she tested with an egg as a hydrometer.  In the meantime she had been saving up all the waste grease from the frying pan and pork rinds from the plate and by trying out these she got her soap fat.  Then on a day set apart for this disagreeable process in chemical technology she boiled the fat and the lye together and got “soft soap,” or as the chemist would call it, potassium stearate.  If she wanted hard soap she “salted it out” with brine.  The sodium stearate being less soluble was precipitated to the top and cooled into a solid cake that could be cut into bars by pack thread.  But the frugal housewife threw away in the waste water what we now consider the most valuable ingredients, the potash and the glycerin.

But the old lye-leach is only to be found in ruins on an abandoned farm and we no longer burn wood at the rate of a log a night.  In 1916 even under the stimulus of tenfold prices the amount of potash produced as pearl ash was only 412 tons—­and we need 300,000 tons in some form.  It would, of course, be very desirable as a conservation measure if all the sawdust and waste wood were utilized by charring it in retorts.  The gas makes a handy fuel.  The tar washed from the gas contains a lot of valuable products.  And potash can be leached out of the charcoal or from its ashes whenever it is burned.  But this at best would not go far toward solving the problem of our national supply.

There are other potash-bearing wastes that might be utilized.  The cement mills which use feldspar in combination with limestone give off a potash dust, very much to the annoyance of their neighbors.  This can be collected by running the furnace clouds into large settling chambers or long flues, where the dust may be caught in bags, or washed out by water sprays or thrown down by electricity.  The blast furnaces for iron also throw off potash-bearing fumes.