USEFUL PROJECTS. 



861 



slieets of fine paper, on which arc nut ; wrap them in a piece of 



placed pasteboards of the same di- Avhite and very clean linen, which 



tensions. Thus arranged, they arc lias been previously dipped iu wa- 



disposcd one above the other, and ter, and squeezed in the liand <« 



put into the press, where thoy must jjress out tlie suiser-abandant water, 



remain at Ica^t twenty-four hours. Extend the stuft" (hat is spotted on a 



When the engravings are very table, on which a very clean napkin 



valuable, they may be put into the has iirst been spread ; then take thii 



press with plates of copper of the cloth containing the charcoal by 



same size as the print itself, which four corners, and lay it upon th« 



imparts to them the highest degree spot. Lift it up and put it down 



oi' beauty and freshness. Care must ag.iin on the spot ten or twelve 



afterwards be taken to expose them times successively, pressing lightly 



to the air and to the sun, to dis- upon it, and the spot will entirely 



sipate entirely the smell of tlie oxy- 

 genated muriatic acid, and not to 

 put them into port-folios till they 

 are perfectly dry. In spite of all 

 the above-mentioned precautions, 



disappear. When the spot is con- 

 siderable, it sometimes goes througTi 

 the stuff, and the grease or oil is 

 imbibed by the napkin. But whe- 

 ther this is the case or not, when 



there may remain on the backs of you lay the charcoal on tliespota 

 those which were glued yellow spots, thick vapour rises from it, whiclx 

 produced by the action of the oxy- has the smell of the substance that 

 genated muriatic acid on the ani- caused it. Hence it is to be pre- 

 dial matter of the glue ; but these sumed, that the heatdilfused by the 

 may easily be removed by sulphuric burning charcoal volatilizes the 

 acid. water of the cloth in which they arc 

 By the method here stated, I have wrapped, and thus d.-composes the 

 cleaned several hundreds of en- grease and oil, which it reduces to 



gravings in one day, notwithstand- 

 ing the extraordinary pains I was 

 obliged to bestow on such a great 

 number of very rare and valuable 

 prints, almost all of which were 

 proof impressions, such as the bat- 

 ties of Alexander, some of fho most Account of Suhmarine Mines in Corn- 



vapours. So much, liowever, is 

 certain, that no spot of the above- 

 mentioned nature has ever resisted 

 this process. 



beautiful landscapes by W'ooilett, 

 kc. 



Alrt/iod of removing Spots of Grease. 



call, hy Mr. Jlaukhu. 



The mine of Huel-Cok, in the 

 parish of St. Just, in Cornwall, 

 which descends eighty fathoms, ex- 

 tends itself forward under the bed 

 M. Lenormand has discovered a of the sea beyond low- water-mark, 

 new and easy method of instantly In some places the miners have only 

 removing spots of oil, grease, and three fathoms of rock befcweun them 

 tallow, from any kind of stuff what- and the sea ; so that they hear very 

 ever, without changing its colour, distinctly the movement and the 

 Take five or six pieces of lighted noise of the waves. This noise is 

 pharcoaL about the size of a wal- somc-times terrible, aud of an cx- 



, 4j»e;'dioary 



