DDT Is Born 41 



and then 1,000 parts of sulfuric acid monohydrate are 

 added. Whilst stirring well, the temperature rises to 60°C. 

 and then sinks slowly down to room temperature, the mass 

 then containing solid parts. It is poured into a great deal of 

 water, whereupon the product separates in solid form. It is 

 well washed and crystallized from ethyl alcohol forming fine 

 white crystals, having a weak fruit-like odour." 



In 1945, almost 33 million pounds of DDT were pro- 

 duced in the United States, and for practically the entire out- 

 put, batch processes similar to that described above were em- 

 ployed. Production was stepped up even higher in 1946, 

 but the method of manufacture has remained virtually un- 

 changed. To the chemical engineers in the industry, this 

 has been rather disconcerting, for every time a chemical en- 

 gineer encounters a batch process he gets an almost uncon- 

 trollable desire to replace it with a continuous process, and 

 thus decrease the cost of manufacture. Engineers lost no time 

 in applying their skills to DDT manufacture; and it was not 

 long before continuous processes were announced. But, ap- 

 parently, all the problems associated with continuous manu- 

 facture have not yet been solved; at least, no continuous 

 process is, as yet, in commercial operation on a large scale. 



DDT is insoluble in water, and this property has an im- 

 portant bearing on the way this insecticide has to be formu- 

 lated. Since you can't dissolve DDT in water, you must 

 dissolve it in some organic solvent in order to obtain a product 

 that you can spray around the house. Numerous solvents 

 can be used, but the most common — because of its low cost 

 ^ — is kerosene or some other petroleum distillate. Of course, 

 for many applications it is not necessary to use DDT in solu- 

 tion form — it is often advantageous to apply it in the form 

 of a powder. But even for application in this form, you 

 couldn't use 100 % DDT even if you wanted to. The crystals 



