148 Practical Hints. 
Avtificial Sponge-iRearing. 
This is being carried out in Styria by Professor O. Schmidt, of 
Gratz. From a report to the Board of Trade, it appears that the 
Professor, by taking small pieces of living sponge and planting 
them in favourable spots, has obtained large sponges in the course 
of three years. It is stated that 4,000 sponges cost no more for 
cultivation and interest on capital than 225 francs, and the 
Austro-Hungarian Government has authorised the protection of 
this new industry on the coast of Dalmatia. 
Practical Hints. 
Shading Oak.—A very fine yellow shade may be given to oak 
by mixing three ounces of tallow, three-fourths of an ounce of 
wax, and one pint of turpentine. Melt in a kettle of hot water, 
mix thoroughly, and apply as hot as possible. Polish by rubbing 
with a piece of leather. 
To Brighten Tarnished Gold and Silver—Wash the articles in 
one ounce of liquor potassee, mixed with twenty ounces of water ; 
then rinse them in warm water, after which they should be 
immersed in a preparation composed of one part of common 
salt, one part of alum, two parts of saltpetre, and three parts of 
water. ‘They are to be washed again in water, dried in chamois 
leather, and placed in sawdust to dry. 
To Mellow the Colours of Paintings on Canvas.—A freshly- 
executed painting may have its colours presented in the mellow 
tones of the old masters by first covering the back with a coating 
of Fuller’s earth, which absorbs all the remaining oil, and then, on 
removing it, covering the back with a coat of linseed oil, which 
the colours presently imbibe. This is the alleged discovery of a 
celebrated French painter. 
To Prepare Stencils—-The best material for paper-stencils is a 
heavy manilla paper. A day or two before using it, it should be 
tacked up somewhere, and given a good coat or two of linseed oil. 
This renders it of the requisite pliability. In cutting the design, 
the edges should be laid on glass to secure smoothness. 
To Polish Mahogany and Walnut Furniture—Dissolve bees’- 
wax by heat in spirits of turpentine until the mixture becomes 
viscid, and rub thoroughly with a flannel or cloth. A gloss may 
also be obtained by rubbing with linseed oil, and then with a 
cloth dipped in very fine brick dust. 
