138 DATE GROWING 



injury to a distance, then ripened artificially, and 

 marketed in a fresh and prime condition. 



Work in Arizona was first begun with the use of 

 moist heat, and this was carried on until successful 

 results were obtained, with the drawback that much 

 of the cane sugar was turned into invert sugar.* 

 Dr. A. E. Vinson then took up the use of chemicals, 

 and found many which would induce artificial ripen- 

 ing. Some of them, however, had the disadvantage of 

 making the dates inedible, because of their own odors, 

 e.g., gasoline and ammonia. Among the sub- 

 stances which gave fairly good results were benzoic 

 acid, salicylic acid, sodium benzoate, sodium salicylate, 

 sodium acetate, potassium acetate, oxalic, malonic, 

 succinic and lactic acids, acetamide, formamide, 

 hippuric acid, cinnamic acid, and hydroxylamine 

 chlorhydrate. He finally settled on nitrous ether as 

 the most desirable agent, but has since given this up 

 in favor of carbon dioxid, which is now used to 

 ripen most of the dates sold from Tempe Experiment 

 Station, t 



The basis of this application is the fact that the 

 date, when it is ripening naturally, liberates large 

 quantities of carbon dioxid. It was, therefore, 

 assumed that this gas played an important part in 

 ripening the dates, and experiment has shown this 

 to be the fact. 



*But this is hardly a real disadvantage, for most good (and bad) 

 dates are invert sugar dates. Up to the present only two varieties 

 have been found which are cane sugar fruits: Deglet Nur and Ma- 

 kantishf, of North Africa, and even these always contain at least a 

 small percentage of invert sugar, just as all ripe invert sugar dates 

 contain a little cane sugar. 



fVinson, A. E. "Chemistry and Ripening of the Date." Univ. 

 of Ariz. Agric. Exp. Sta. Bui. No. 66, Tucson, May 1, 1911. The 

 results of the work with carbon dioxid have not yet appeared in 

 print, however. 



