256 INORGANIC CHEMISTRY 



chemistry had to wait till the researches of Troost and Hautefeuille, 

 published in 1873, before knowing the laws of the transformation of 

 cyanogen into its polymere paracyanogen. 



I might further cite for you on this point Humphry Davy's method 

 of work; I might recall to your minds the fact that Wohler was a 

 master of chemical analysis, and outline for you the excellent studies 

 of Berzelius or of Stas. If I have lingered on this topic, it is because 

 I regard it as most important. Many great investigations remain to 

 be made in inorganic chemistry, but to get them done, the methods 

 must be refined and attain great precision. In a word, experimental 

 research in chemistry should have the rigor of physical experiments. 



But to return to the relations of chemistry with the other sciences. 

 We have already spoken of physics and biology. I do not wish to 

 enlarge beyond measure on this point. I will remind you that astro- 

 nomy, thanks to spectrum analysis, the joint product of physics and 

 chemistry, has been able to extend and develop certain of its theories 

 to include the remotest star visible in our horizon. Moreover, the 

 spectroscopic method of Doppler and Fizeau has been of great serv- 

 ice in determining the speed of the heavenly bodies. 



Our chemistry also comes into contact with mathematics at two 

 important points. It comes into contact with statics in stereochem- 

 istry and the special grouping of atoms, in questions of symmetry 

 and in combinational analysis which studies the combinations of 

 objects associated in different conditions. It comes into contact 

 with mathematics also on the dynamic side, in that it involves the 

 principles of molecular mechanics in connection with the conservation 

 of energy and the mechanical theory of heat. 



Chemical analysis is one of the foundations of mineralogy. It is of 

 the greatest service to geology, which could not do without it. The 

 majority of the sciences have need of its assistance, and even the 

 historian comes to it to inquire the age of the successive foundations 

 of the ruins of Babylon, bringing to it the bronze or copper objects 

 which the latest excavations have put into his hands. 



When it comes to industrial applications of the various sciences, 

 very few of them are not in debt to chemistry. The engineer has con- 

 stant need of it. Studies of the metals and their alloys have given 

 all their efficiency to machines, ships, and firearms. Two chapters, 

 however, in the applications of science will depend absolutely on the 

 progress of chemistry; we refer to the chemical industry and to 

 rural economy, so important that they change the destinies of 

 nations, mingle the stocks of peoples, and modify the conditions of 

 their existence. 



It is not our part to enlarge upon this side of the question; it is 

 enough to have mentioned it, and to recall, in closing, the vast sum 

 of effort which these researches have demanded. In the midst of 



