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Dr. A. W. Hofmann 



[April 11, 



subject, and need not therefore specially be noticed. In fact, the only 

 coal-derivatives which, in connection with Mauve and Magenta, claim 

 our attention, are Benzol, Phenol, and Aniline ; those certainly we 

 must by-and-by examine somewhat more in detail. 



But before doing so, you legitimately expect that I should endea- 

 vour to give you some idea of the nature of the process, in which this 

 endless variety of compounds is generated from coal. Were I 

 to tell you simply that coal consists of Carbon, Hydrogen, Nitrogen, 

 Oxygen, and Sulphur, not to mention the ash which is left after combus- 

 tion, and that you may therefore look upon coal as a sort of magazine 

 of these several elements, capable, under the influence of heat, of 

 associating in an infinity of forms and proportions, you would have 

 learnt comparatively little. Let me attempt to convey to you a some- 

 what more precise idea of the processes involved in the distillation of 

 coal. For this purpose you must allow me to remind you of some of 

 the general results elaborated by the researches of chemists during 

 the last ten years, which, at the first glance, appear but little connected 

 with Mauve and Magenta. 



The infinite number of substances, mineral, vegetal, or animal, 

 which form our planet, variously as they are composed, may be re- 

 ferred, — chemists now pretty generally agree, — to a comparatively 

 small number of types of construction. Opinions are divided respect- 

 ing the actual number of these types, and even the choice of typical 

 bodies is still a subject of discussion among chemists. But whatever 

 the special views of particular schools may be, the number of types is 

 always small, and among them almost invariably figure Hydrogen, 

 Water, and Ammonia. The comprehension of the meaning attached 

 by chemists to the term types may perhaps be facilitated to you by 

 a glance at three models which I have had constructed for this pur- 

 pose, and which for the sake of convenience I may be allowed to 

 designate as type-moulds.* 



Chemists assume that the smallest particle of hydrogen, which 



♦ These type-moulds consisted essentially of wire frames, presenting the out 

 lines of cubes, associated, two, three, or four of them, in the manner indicated 

 in the diagram 



DD 



and capable of receiving zinc-cubes variously painted and marked, representing 

 elementary and compound atoms. 



