EUCALYPTUS XEBES. 95 



bucketful of wood-ash, such as yfe daily remove from 

 our domestic fire-places, contains about twenty-five 

 pounds, from which, accordingly, about two and one 

 half pounds of inferior, or one and one fourth pounds 

 of superior potash, may be obtained ; the former 

 being worth about sixpence per pound, the latter 

 double the price. For ascertaining the contents of 

 carbonate of potassa in crude potash or pearlash, cer- 

 tain instruments, well known as alkali - meters, are 

 constructed. The heaviest ashes, as a rule, contain 

 the greatest proportion of potash. The brake-fern, so 

 common on many river-banks and sandy tracts of the 

 country, is rich in this alkali. 



Apart from my subject, I may, however, say that 

 there are other sources of potash-salts than trees alone. 

 Chloride of potassium is obtained from some large 

 salt-beds, for instance, in Prussia. Prom this source it 

 was supplied to British manufactories, in 1869, to the 

 extent of one hundred and fifty-four thousand four 

 hundred and sixty-eight hundred weight, valued at 

 above £60,000. This chloride is besides obtained, under 

 Mons. Balard's process (Report of Juries at the Inter, 

 national Exhibition for 1862), in considerable quanti- 

 ties from sea-water, as one of the contents to be util- 

 ized. From this chloride the various potash salts, 

 otherwise largely obtained from pearlash, can be also 

 prepared. Chlorides and sulphates, if they occur in 

 crude potash, can, in the process of purification, almost 

 completely be removed through crystallization from 

 the greatly concentrated solution. 



Let us now approach another forest industry, one 

 quite unique and peculiar to Australia — namely, the 

 (JjstiUation of volatile oil from Eucalyptus s^n4 allied 



