342 Fruit-growing in Arid Regions 



is the deposit of soot left on the almost mature fruit. This 

 defect does not enter into the discussion in deciduous 

 fruit-growing sections, where the fires are needed only 

 during the blooming period or shortly after the fruit is 

 set; practically all trace of the deposit disappears before 

 the fruit is picked. Even in California this objectionable 

 feature could be partially overcome by choosing an oil 

 burner that would consume the fuel more perfectly than 

 the one now commonly used in the citrus orchards. Cali- 

 fornia growers have used crude petroleum, which can be 

 purchased at the wells at a lower price than coal. In 

 many fruit sections the conditions would be reversed. 



Coal has been used in California, but with rather un- 

 satisfactory results. California growers have given out 

 the impression that it is possible to raise the temperature 

 only four or five degrees with coal. The fact that Cali- 

 fornia growers have tried to burn coal in an unsatisfactory 

 burner is no doubt responsible for this false impression as 

 to its heating value. This California coal burner is noth- 

 ing more than an open wire basket, without draft, and it 

 has been impossible to burn a sufficient quantity of coal. 

 In other sections several types of coal heaters have been 

 invented, and after one season's trial it is safe to say that 

 with a satisfactory coal burner it is possible to raise the 

 temperature as much as with an oil burner. 



Local conditions will determine which will be the cheaper 

 fuel. With gas oil or crude oil delivered at four and one- 

 half cents per gallon, coal will probably be no more ex- 

 pensive at $4.50 per ton. One can count on about as 

 much heat from a ton of coal as from 100 gallons of oil. 

 With one year's actual experience in the use of these heat- 



