( 443 ) 



ing themselves at such a research ai'e so great that a really com- 

 plete investigation with a satisfactory scieiitilic result can hardly be 

 expected. The motive and object of this research were also of a 

 technical character ; the method applied necessitates, however a 

 theoretical explanation. 



The results as yet obtained are generally not capable of satis- 

 fying the critical reader; on one hand they have rarely led to con- 

 cordant results on the other hand it is not possible to get from 

 the known observations a good insight into the connection of the 

 phenomena. 



And still this insight is a matter of great technical importance. 

 One might perhaps remark that in the course of years, a modus 

 operandi has developed in the sugar industry which, on the whole, 

 yields satisfactory results and that a scientific and accurate investi- 

 gation of the phenomena is not of any great importance for technical 

 purposes. I wish to be allowed to briefly answer this often quoted 

 remark. 



A fact is that, although there exists a fairly satisfactory working 

 process, there occur not unfrequently difficulties and confusions of 

 which one does not know the cause and for which no satisfactory 

 remedy is known. The chemical industry has two methods of expe- 

 rimenting at its disposal ; the practical experiment at the works, and 

 the laboratory experiment. 



The practical experiment generally takes the following characte- 

 ristic course. If a process does not work smoothly and if difficulties 

 are experienced in the ordinary method of working the latter is 

 altered but in such a manner that 1. the usual method is departed 

 from as little as possible, so that there is no risk of a serious failure 

 involving great financial loss. 2. The experiment has its limitations 

 depending on the nature, the size and the construction of the appa- 

 ratus at disposal. For instance, it will often be impossible to attain 

 a temperature considerably higher than the normal one because the 

 capacity of the heating arrangement at disposal is insufficient. 



If now the experiment carried out in this manner has a not 

 unfavourable result, tha circumstances are remembered and these 

 are again applied another time. Should the result be again favourable 

 a rule is gradually introduced : If under certain conditions some 

 difficulty or other arises, act according to the particular recipe given. 



Some of those rules have obtained the significance of laws whose 

 discovery has meant a real industrial progress ; but there are many 

 others whose applications have done more harm than good. The 

 practical experiment, although very useful, is not sufficient. 



30 



Proceedings Royal Acad. Amsterdam. Vol. XIV. 



