52 LIFE AND EXPERIENCES CHAP. 



eventually the " Bunsen burner" came to light. This 

 is now universally employed, not only for chemical 

 but for a great number of other purposes in the arts 

 and manufactures, so that this burner is even more 

 widely known than the zinc-carbon battery which also 

 bears his name. 



Another well-known instrument invented by Bunsen 

 (1844) is the photometer, which he devised for 

 measuring the illuminating power of coal-gas. The 

 essential feature of this apparatus is a disc of paper 

 having a grease spot in the centre, a comparison of 

 the luminous intensity being made when by the ap- 

 proximation of the source of light to the illuminated 

 disc the spot becomes invisible. When the instrument 

 was shown and explained to the late Emperor 

 Frederick he remarked, " For the first time in my life 

 I now know the value of a spot of grease." 



It is not only his inestimable additions to pure 

 Science, upon which this is not the place to 

 dilate, that mark Bunsen as one of the foremost 

 scientific men of his age ; he is no less distinguished 

 by his contributions to its industrial applications. 

 Perhaps the most important of these was the re- 

 volution he effected in iron manufacture. He made 

 the first successful attempt to introduce accurate 

 scientific methods and inquiry into this great industry. 

 Up to 1845 tne production of cast-iron in the blast- 

 furnace was carried on largely in ignorance of the 

 scientific principles upon which it depends. The 

 waste of fuel was enormous, amounting often to 

 80 per cent of the whole. Bunsen, by analysing the 

 escaping gases from the blast furnaces at Alfreton, in 

 Derbyshire, showed how this loss could be obviated 

 and the heat of the burning gases utilised ; and, in 

 conjunction with the late Lord (then Dr. Lyon) 



