1818.] Scientific Intelligence. 145 



heraatine to assume the blue colour, a circumstance which con- 

 nects it with the salifiable bases. 



VI. Method of making Salt in the Great Loo-choo Island.* 



Near the sea, large level fields are rolled or beat so as to have 

 a hard surface. Over this is strewn a sort of sandy black earth, 

 forming a c at about a quarter of an inch thick. Rakes and 

 other implements are used to make it of a uniform thickness, 

 but it is not pressed down. During the heat of the day, men 

 are employed to bring water in tubs from the sea, which is 

 sprinkled over these fields by means of a short scoop. The heat 

 of the sun, in a short time, evaporates the water, and the salt is 

 left in the sand, which is scraped up and put into raised reser- 

 voirs of masonry about six; feet by four, and five deep. When 

 the receiver is full of the sand, sea water is poured on the top ; 

 and this, in its way down, carries with it the salt left by the 

 evaporation. When it runs out below at a small hole, it is a 

 very strong brine; this is reduced to salt by being boiled in 

 vessels about three feet wide and one deep. The cakes result- 

 ing from this operation are an inch and a half in thickness. 



The above account will be considered interesting, both as 

 exhibiting the degree of perfection to which the arts of life have 

 been carried in that remote and insulated country, and as being 

 essentially the very same process which is practised on the 

 western coast of France, particularly in Lower Normandy, and 

 at the isles of Oleron and Rhe. — (See Journ. des Mines, No. 7, 

 p. b'l ; Encyc. Meth., Arts and Metiers. Article Salines. — Ed. 



VII. On Street Illumination. By John Millington, Esq.f 



After remarking upon the very imperfect state of the old oil 

 lamps that are employed in the streets of London, and the 

 important improvement made* upon them, first by Lord Coch- 

 rane's lamp, in which the combustion is promoted by a current 

 of air entering at the bottom of the glass, and still more by the 

 use of coal gas, Mr. Millington proposes an alteration in the 

 reflectors that are employed. As the author properly observes, 

 the object is not to produce a concentration of light, but an 

 equable diffusion of it, exactly the reverse of the effect which is 

 produced by the lenses which still dazzle the eyes in some parts 

 of the metropolis. The reflectors employed by Lord Cochrane, 

 although the best that have been employed so far as their form 

 is concerned, are defective from the material of which they are 

 composed. This is tinned iron, which although it is at first 

 sufficiently brilliant, yet it soon loses its brightness by the smoke 

 winch adheres to it, or by the friction necessary for keeping it 



* Extracted from Capt. Hall's " Account of a Voyage of Discovery to the 

 Wwl Coa i of Corea, anil (he great Loo-choo Island." 



+ Altridg il from the Journal of Science and the Arts, v. 17. 



Vol. XII. IN II. K 



