148 Report on the Progress of Chemistry. 



pounds. So rapidly do these discoveries follow each other 

 that to simply name those which have been brought to light 

 during the past year alone would be an unwelcome task 

 at this time. 



But fruitful as this theory of atomicities has proved to 

 be, and intimately as it has been allowed to weave itself 

 into the very foundations of the science of chemistry, it is 

 still far from being exempt from the most rigorous examin- 

 ation and of the severest criticism. A remarkable paper 

 was read before the American Association at its Troy meet- 

 ing in August last (1870) in which Mr. F. W. Clark sub- 

 jected the theory to what "seems to be a calm and searching 

 review. After naming compounds by way of illustrating 

 the failure of the theory in important cases, the author de- 

 clares that " such compounds seem to be absolutely inex- 

 plicable by any of the ordinary forms of the theory of 

 atomicities," and the arguments employed are sufficiently 

 vigorous to make us await anxiously the reply of the ad- 

 vocates of the theory to the charge made in the concluding 

 words of the sentence, just partly quoted, when, of these 

 inexplicable compounds it is added, "in fact it seems as 

 if theoretical chemists had run away from and ignored them." 

 The author finally expresses his opinion that "for the 

 present we must look upon the doctrine of atomicities as 

 a convenient but faulty system of mnemonics which, pro- 

 perly used, enables us to grasp and handle large masses 

 of facts, but which when misunderstood and regarded as a 

 law, only leads us into confusion." An attack of this kind 

 will doubtless be seized by chemists as affording them an 

 opportunity to strengthen the foundations of their science 

 by extending or modifying the applications of the doctrine of 

 atomicities. To give up the theory itself seems to be out 

 of the question. The roots of the tree may be hidden; the 

 trunk itself may be covered with fungi, but from its branches 



