Mechanical Science. 423 



4. Cleansing of Orchard Trees by Lime. — The use of lime luis 

 been highly recommeiulod in the dressing of old moss-eaten 

 orchard trees. Some fresh-made lime being slaked with water, 

 and some old worn-out apple-trees well dressed with it with a 

 brush, the result was that the insects and moss were destroyed, 

 the outer rind fell oft", and a new, smooth, clear, healthy one 

 formed : the trees, although twenty years old, assuming a most 

 healthy appearance. 



5. Purification of Oil. — A method of purifying common fish 

 oil, and rendering it equal to the best sperm oil, by the use of 

 animal charcoal, is described as having been discovered in Den- 

 mark. The description is very incomplete, but mentions that 

 beef bones which have been boiled, are made into animal charcoal 

 in a peculiar way. The charcoal is mi.xed with the oil, and 

 repeatedly agitated for two months, after which it is filtered through 

 several strata of charcoal, and used as soon as made. 'I'he quan- 

 tity of gas evolved by the bones in the operation is considerable, 

 and is used for lighting the manufactory and adjacent buildings. 

 The residuum is mixed with clay for fuel. The loss in this 

 process is estimated at 15 per cent., and the gain is equal to 40 

 per cent., leaving a balance in favour of the discovery of 25 

 per cent. 



The peculiar method of making the charcoal, probably con- 

 sists in not heating the bones too much. It is well known by the 

 animal charcoal makers in London, that if the temperature be 

 raised too high, the charcoal is worth nothing. 



6. Oil Gas. — Mr. Wilson proposes obtaining this gas in 

 countries where the oil is chiefly vegetable, by introducing the 

 seeds themselves into the retorts, much in the manner that 

 coals are used here. Besides saving the expense of preparing 

 the oil, it is supposed that the charcoal left may be useful and 

 valuable. We, however, greatly doubt the plausibility of this 

 proposal, 



7. Purification of the Water of the Seine at Paris. — There is 

 an establishment in this city (Paris) for purifying for domestic use 

 the water of the Seine, which gives constant employment to up- 

 wards of 200 persons. The water is pumped into vessels about 

 20 feet deep, and as many in width, where it reposes 12 hours. 

 'J'he clear water is then raised into another vessel, whence it 

 flows into long and shallow cisterns, on the sides of which a great 

 number of sponge filters are placed, and the sponges are renewed 

 every hour. From the sponge filters it finds its way into square 

 shallow cisterns, each of which has at the bottom a bed of clean 

 Fontainebleau sand, then a bed of pounded charcoal, then another 

 bed of clean sand, and lastly, at top, abed of coarse river sand, 

 (these last-mentioned filters are renewed every six hours) ; and 



