PRODUCTION OF POTASH SALTS. 35 



Total Potash (K,0) 42-46 



The relative proportions of these salts are also indicated, and 

 it is observed that the bulk of the potash occurs as carbonate 

 and sulphate, which are the two most important potassium salts. 



As forest contains by far the largest volume of plant tissue 

 per unit of area of any land, it was decided to conduct experi- 

 ments relating to the production of plant ash in woodlands. 

 The investigation was extended to include land producing a 

 dense volume of weed growth, such as is obtained in the case 

 of bracken land. The experiments were conducted with due 

 regard to present economic conditions, and all calculations of 

 costs are based upon these. 



Quantities Available. 



It was not deemed advisable to give separate figures for 

 different types of woodlands, e.g., high-forest, coppice and scrub, 

 since the density of stocking varies so much. It was found 

 however, that taking the " lop and top," undergrowth, weed 

 growth and litter, in any average type of woodland about half a 

 ton of ash was produced per acre. On the basis of there being 

 three million trees cut this year for pitwood and other purposes 

 in plantations containing on the average three hundred trees per 

 acre, some five thousand tons of ash would be rendered 

 available. 



In all portable saw-mills and foreign timber-mills where wood 

 constitutes the fuel, ash is a by-product. On investigation it 

 was found that such mills produce about quarter of a cwt. of 

 ash per day. Throughout Scotland there are probably not less 

 than five hundred mills producing wood ash, which, if they work 



