Jd.ve 1, 1865.] THE TECHNOLOGIST. 



ON MAGNESIUM. 495 



necessarily small, the mirrornot being more than two centimetres square 

 But on a bi-convex lens being placed before the patient's mouth, the 

 image became so enlarged, that every one could distinguish it from a 

 distance of a few metres. These two applications of important scientific 

 discoveries and contrivances combined are highly interesting ; in the 

 first place, by the aid of the magnesium light, the exact site of the 

 slightest sore in the upper respiratory organs may be discovered by phy- 

 sicians ; and in the second place, the same may be rendered visible to a 

 numerous audience." 



One of the peculiarities of the magnesium light is, that it displays 

 colour as in sunshine. This may be tested, and a very interesting effect 

 produced, by burning some wire in a garden or conservatory at night. 

 This peculiarity we learn, from the 'British Journal of Photography,' is 

 being turned to practical account. 



" The magnesium lamp promises quickly to become a regular article 

 of furniture in every silk mercer's show-room. A dyer, of Paris, some 

 months ago, saw the magnesium light for the first time, and discovering 

 at once that its rays left colours unaffected, exclaimed, 'This is just what 

 we have long wanted.' Even in Paris there are many days in winter 

 when those who deal with delicate shades of colour are utterly at a loss 

 to discriminate between tint and tint, but the magnesium light has com- 

 pletely removed the difficulty. Now, whether it be fog or night, any 

 question as to colour is in a moment set at rest in the flame of a bit of 

 magnesium wire." 



The strength of the magnesium light coupled with its easy produc- 

 tion qualifies it for extensive employment in commerce and war. Unlike 

 the electric and oxy-hydrogen lights, it involves no cumbrous and trouble- 

 some apparatus. With a coil of the wire in his waistcoat pocket and a 

 few matches, an Alpine explorer has instant means for making his 

 whereabouts known at night. The light has been seen at a distance of 

 twenty-eight miles at sea ; how much further remains to be determined. 

 Commissions under several Governments are investigating its capabilities, 

 and there is reason to believe that it will very soon be adopted for ship 

 signals and lighthouses. It has been suggested that rockets primed with 

 magnesium in powder and thrown up at uncertain intervals would effec- 

 tually prevent a night surprise, as they would light up the country for 

 miles around. By the same means many of the secrets of an enemy's 

 works and position might be discovered. Had the United States' Navy 

 possessed the light sooner, the hazards of blockade-running would have 

 been indefinitely increased. Its merits were only revealed when the 

 opportunities for its employment were passing away. We read in ' The 

 Times ' of 20th February of the present year — 



" It appears that, according to Federal anticipations, blockade-run- 

 ning is likely to suffer a check by the introduction into the American 

 Navy of the new magnesium light, of which metal the Washington 

 Government has ordered a supply. Several of the European Govern- 

 VOL. V. 3 F 



