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SCIENCE. 



[N. S. Vol. II. No. 36. 



cussion and led them to profitable study 

 regarding them and the fundamental and 

 natural laws upon which they were based. 

 And what was true of that earlier pei'iod 

 of the history is true to-day and to an 

 increasing degree must find, illustration 

 in future work. The industries are still 

 pushing forward with earnest competition 

 to supply the demands which grow with 

 the years, and the hard questions which 

 come from managers and proprietors to pro- 

 fessional men are as numerous and as diffi- 

 cult in their way as those which puzzled the 

 early philosophers and stimulate an earnest- 

 ness in endeavor and investigation that 

 brings the highest and most useful results. 

 We must admit that without these hard 

 questions the advances in the science itself 

 would be less rapid and the intellectual 

 activities of investigators less alert. 



Beautiful illustrations growing out of 

 such demands are everywhere to be seen at 

 the present day even as they were in for- 

 mer years, although they are not often to 

 be found recorded in the pages of published 

 history. Many of us will remember the in- 

 cident cited by Hoffmann-'^ in his necrolog- 

 ical notice of Dumas describing the circum- 

 stances which led to the discovei-y of the 

 absorption of chlorine by organic bodies, in 

 which he declares that it "is not gener- 

 ally known that the theory of substitution 

 owes its source to a soiree in the Tuilei'ies." 

 Dumas has been called upon by his father- 

 in-law, Alexander Brogniart, who was di- 

 rector in the Sevres Porcelain Works, and, 

 as Hoffinann says, in a measure a member 

 of the royal household, to examine into the 

 cause of the irritating vapors from candles 

 burned in the ball room, a demand to which 

 Dumas readily acceded, because he had al- 

 ready done some work upon the examina- 

 tion of wax which could not be bleached and 

 was therefore unmerchantable . He was read- 



*Berichte der Deutsclieu Chemisolien Gesellscliaft. 

 17 R. 667. 



ily led to the conclusion that the candles used 

 in the palace had been made with wax which 

 had been bleached with chlorine and that 

 the vapors were hj^drochloric acid gener- 

 ated in the burning of the candles. But 

 examination of the wax of the candles 

 showed that the quantity of cMorine found 

 was greater than could be accounted for by 

 its presence as a mechanical impurity, and 

 from it Dumas was led to experiments which 

 showed that many organic substances when 

 heated with chlorine have the power to fix 

 it, and from these results he was in turn 

 led to the further generalization concerning 

 the law of substitution. In this connection 

 Hoffmann says: "This information upon 

 the origin of substitution, which the author 

 of this sketch had from the mouth of Du- 

 mas himself, is more than an interesting in- 

 cident. We frequently see that like the 

 Luxembourg palace, the Tuileries, besides 

 their historical legends, have likewise scien- 

 tific memories. How wonderful! A ray 

 of sunlight refiected from the window of the 

 Luxembourg, and accidentally seen by Ma- 

 ins through a plate of calcspar, revealed to 

 him the phenomenon of double refraction, 

 addinganewprovince to the domain of phj'^s- 

 ics ; whUe the acid vapors from a smoking 

 burning candle in the ball room of the Tuil- 

 eries led Dumas to study the influence of 

 chlorine upon organic bodies, and finally led 

 him to speculation upon this action, which 

 for many j^ears had controlled the science 

 and even to-daj^ has a mighty influence 

 upon its development." 



It would be difficult to foUow Dumas 

 through the hundreds of investigations he 

 made in all the fields of chemical activity, 

 clearing up the the questions arising in the 

 various occupations of daily life and in all 

 its departments, even as it would that of 

 other men active in progressive work. 

 Much of the work of Dumas, as shown by 

 Hoffmann and the published records, was 

 devoted to the solution of such questions, 



