THE success of Professor Gattermann's book in the originalhas warranted its reproduction in English. The translation isintended for those students of chemistry who have not yetbecome sufficiently familiar with scientific German to be ableto read it accurately without constant reference to a dictionary.To such students this translation is offered, in the hope that itwill increase their interest in the science without causing a cor-responding decrease in their efforts to acquire a knowledge ofGerman, which is indispensable to every well-trained chemist..