630 BUNSEN MEMORIAL LECTUHE. 



flow of water earning down Avith it a sufficient volume of air — on the 

 principle of the steam injectt^r — to create a diminution of pressure, 

 which, although b}' no means so great as that eftoctod by the filter 

 pump as described by Bunsen, is still sufficient for many purposes. 



As another example of the far-reaching character of his work, a few 

 words must be said al)Out his experiments on tlie products of the tiring 

 of gunpowder. 



The nature of the reaction taking place in the firing of gimpowder 

 has attracted the attention of chemists from earh- years. The accu- 

 racy of the simple equation, which at one time was believed to express 

 this reaction, was long ago rendered doul)tful l)v the observations of 

 Gay-Lussac and Chevreul, but the first exact investigation of the com- 

 position, both of the gases and of the solid products of the explosion, 

 we owe to Runsen and Schischkoff (Pogg. Ann., 1857 (102), 821). The 

 points of importance which the}' ascertained were, in the first ])lace, 

 that a large number of salts, whose presence had hitherto not l)een 

 detected, were shown to be normal constituents of the smoki" and solid 

 residue; and, secondly, that many other gaseous products Ix'sidcs car- 

 bon dioxide and nitrogen are formed. 



The powder was burnt under oi'dinarv pressure, and the maxinnim 

 temperature of combustion as well as the maximum pressure were 

 determined. Since 1858 other investigators have taken up this sul)- 

 ject, especially Abel and Noble. Berthelot. and Debus.' All these 

 elaborate and more recent researches bear out the conclusion arrived 

 at by Bunsen and Schischkoff, namely, that it is not possible to give 

 any simple expression for the reaction, the products not only being 

 very numerous, but varying considerably in their proportion accord- 

 ing to the conditions, especially the pressure, and, therefore, the tem- 

 perature, under which the explosion takes place. 



The invention which perhaps more than any other has popularized 

 the name of Bunsen is that of his celebrated burner. 



The Bunsen burner, to the discover}' of which I shall refer later on, 

 is not only important from the fact of its almost universal employ- 

 ment, but also because familiarity with its propin-ties led Bunsen to 

 elaborate a series of flame reactions of very wide applicability. In the 

 communication published in 1866 (Annalen, 1866 (138), 257) he showed 

 that the nonluminous flame of the burner could, with advantage, 

 supplant the blowpipe flame for man}' analytical purposes. He first 

 describes the . constitution of the nonluminous gas flame. Next he 

 examines the action of the high temperature of the flame on the emis- 

 sion of light from solid bodies placed in the flame, referring especially 



^ To Dr. Debus, one of Bunsen' s oldest pupils and friends, I am indebted for par- 

 ticulars of interest connected with Cassel and Marburg. 



