THE PROGRESS OF SCIENCE. 



479 



Amherst College party in charge of 

 Professor Todd was at Singkep, where 

 the sky was very unfavorable. At 

 Mauritius the English astronomers had 

 a fair sky. This eclipse well illustrates 

 the importance of a large number of 

 stations scattered along the belt of 

 totality, for in spite of the clouds which 

 widely prevailed the results from the 

 stations, as a whole, are very satisfac- 

 tory and will encourage similar efforts 

 at coming eclipses. 



THE SPECTRUM OF LIGHTNING. 

 Very wide interest has been taken in 

 the spectrum of lightning, photographs 

 of which have been obtained at the Har- 

 vard College Observatory. These were 

 made by pointing a telescope, provided 

 with an objective prism toward a por- 

 tion of the sky where lightning was 

 particularly bright. The spectrum is 

 not always the same. Many of the 

 lines appear to be due to hydrogen. The 

 first line is a broad, bright band, ex- 

 tending from wave-length 3,830 to 

 3,930, and may be identical with the 

 nebular line 3,875. The spectrum of 

 lightning is curiously like that of the 

 new star in Perseus, and other new 

 stars. Now that the method of obtain- 

 ing such photographs has been shown, 

 it would seem possible to obtain a large 

 number of them, taken under different 

 conditions for a more complete study of 

 the subject. 



THE MANUFACTURE OF SUL- 

 FURIC ACID. 



Of all the products of chemical in- 

 dustry, sulfuric acid has always held 

 the first place, and its importance in- 

 creases yearly, since there is hardly a 

 branch of manufacture in which it is 

 not largely used. Its manufacture by 

 the lead-chamber process has been uni- 

 versal until \vithin a few years. This 

 requires a large plant and the acid ob- 

 tained is dilute. For many purposes 

 this must be concentrated at no incon- 

 siderable expense. Vessels of platinum 



are very generally used and a single 

 still may cost upwards of $10,000. 

 With the development of the coal-tar 

 industry in Germany, and especially in 

 connection with the rapidly increasing 

 manufacture of artificial indigo, has 

 come a demand for the more concen- 

 trated acid in large quantities. 



That imder the catalytic action of 

 finely divided platinum, sulfur dioxid 

 can be burned to sulfur trioxid, which 

 with water gives sulfuric acid, has 

 been known for nearly three quarters 

 of a century, and in 1831 a patent was 

 secured in England for the manufacture 

 of the acid by this process. But in 

 spite of vast amoimts of effort devoted 

 to it, and by some of the world's most 

 distinguished chemists, this has never 

 been made a practical success. Under 

 the stimulus of the demand of the color 

 factories of Germany, this problem has 

 been very actively attacked in the past 

 few years by their chemists, and at 

 last the efforts have been crowned with 

 the desired reward. 



This work has been chiefly carried 

 on under the auspices of the Badischen 

 Anilin- und Soda Fabrik at Ludwigs- 

 hafen. Theoretically the process is a 

 model of simplicity. The gases from 

 the pyrites burners, consisting chiefly of 

 sulfur dioxid, oxygen and nitrogen from 

 the air used, are, after purification and 

 cooling, led through cylinders contain- 

 ing plates on which a contact mixture, 

 with platinum as one of its constit- 

 uents, is placed. The sulfur dioxid 

 burns with the oxygen present in the 

 gas, giving the trioxid, which is ab- 

 sorbed in a dilute acid. The acid ob- 

 tained may be pure sulfuric acid, or 

 may contain an excess of the trioxid — 

 the fuming or Nordhausen acid. Sev- 

 eral years of most patient investigation 

 were, however, required before the con- 

 ditions were discovered by which the 

 process could be kept in continuous 

 operation, there being a great tendency 

 for the platinum mixture to cease its 

 work after a few days' or even hours' 

 use. This was due to the presence of 



