712 



SCIENCE 



[N. S. Vol. XXVI. No. 673 



solution as the result of fifteen years or 

 more of work, a second difficulty presented 

 itself in the magnitude of the interests in- 

 volved. It is estimated that the world uses 

 about 5,000 tons of indigo in a year. 

 Now, even with the perfected methods it 

 takes about four pounds of toluene to make 

 one pound of indigo and the present 

 production of toluene is only about 5,000 

 tons a year. The whole of the toluene pro- 

 duced would give only about one fourth of 

 the amount required to supply the world's 

 demand for indigo. Furthermore, the 

 toluene now produced finds a ready market 

 for use in the preparation of other dyes and 

 other compounds. Any attempt to use a 

 considerable amount of toluene for the 

 manufacture of indigo would be met, 

 therefore, by a rising price which would 

 quickly make the production by this method 

 commercially impossible. 



Fortunately, another synthesis of indigo 

 was discovered by Heumann in 1890 which 

 made it possible to prepare indigo with the 

 use of naphthalin as a raw material. As 

 the supply of naphthalin is ample for the 

 purpose, the second difficulty was over- 

 come. But the new process required the 

 solution of a whole set of new problems 

 and it was not till seven years later that 

 the Badische Anilin and Soda-Fabrik con- 

 sidered that the process was sufficiently 

 well developed to justify preparation for 

 the manufacture on a large scale. So 

 carefully had they worked out every de- 

 tail, however, that during the three years 

 that followed they were willing to expend 

 four and a half million dollars in building 

 the factory and apparatus for this one 

 enterprise. As the world uses in a year 

 twelve to fifteen million dollars' worth of 

 indigo, the manufacture on a large scale is 

 justified, and there is every indication at 

 present that the artificial indigo is slowly 

 displacing the natural product. The 

 farmers in India are already feeling this 



new competition and it is doubtless only 

 a question of a few years before they wiU 

 be compelled to devote their attention to 

 other crops. The hope has been expressed 

 that the land released in this way may be 

 used for raising food products, which may 

 give some relief from the famines so com- 

 mon in that country. 



In 1856, in the same year in which Per- 

 kin discovered mauve, Henry Bessemer 

 presented to the world at the Cheltenham 

 meeting of the British Association the first 

 account of his new process for the manu- 

 facture of steel. Previous to that time 

 steel had been made by a roundabout, tedi- 

 ous process. The carbon was burned out 

 of pig iron in puddling furnaces so con- 

 structed that only comparatively small 

 amounts could be handled at once and the 

 most arduous hand labor was required. 

 From the wrought iron obtained in this 

 way steel was prepared by packing the 

 bars in charcoal and heating them for 

 several days until they had reabsorbed the 

 requisite amount of carbon. Bessemer con- 

 ceived the idea that by blowing air through 

 melted iron it would be possible to burn 

 out the carbon and silicon in the iron, while 

 the heat resulting from their combustion 

 would keep the iron liquid. He thought, 

 too, that if he could stop the blast at the 

 right moment, before all the carbon was 

 gone, he would have steel. He showed that 

 in this way several tons of iron could be 

 converted into steel in fifteen or twenty 

 minutes, whereas the old process took half 

 as many days. Such a revolutionary 

 process attracted a great deal of attention, 

 and he succeeded in selling the right to use 

 the process to a number of manufacturers 

 for a considerable sum of money. When 

 they attempted to make steel by the new 

 method, however, every one of them failed. 

 It was found practically impossible to stop 

 the blow at the right point to secure a 

 uniform product. But Bessemer was not 



