344 Fruit-growing in Arid Regions 



for orchard-heating purposes. Coal containing over 20 

 per cent of slack is not desirable for burning in these 

 heaters. In Colorado, crude oils have not been found to 

 be the most satisfactory for burning in orchard heaters, 

 on account of a tendency to boil over. A product known 

 to the trade as "gas oil" is now being recommended by 

 the oil companies. In fact, this is the only oil they will 

 sell for orchard-heating. While this grade is not always 

 uniform and will not always burn for the same length of 

 time, it will burn as long on the average as crude oil and 

 does not boil over. 



Fuels may be made from various materials as coal slack, 

 tar, crude oil, and shavings. These fuels are now found on 

 some markets and are quite well adapted to orchard-heat- 

 ing purposes. As a rule they are pressed into cakes which 

 may be burned in piles on the ground or in any of the coal 

 burners. Like the coal, it is almost impossible to extin- 

 guish them when once lighted, and the fires require fre- 

 quent stirring to keep them burning freely. 



Cost of Equipment. The cost of equipping the orchard 

 with these oil heaters should not exceed $25 per acre, and 

 the cost of a storage house for coal or a tank or cistern for 

 oil should not exceed $7.50 per acre. A good 400-gallon 

 tank for hauling and distributing oil, equipped with hose 

 similar to the one shown in Figure 95, may be had for 

 about $50. Local tinners will quote a price of about $30 

 on a 300-gallon galvanized iron tank furnished with an 

 outlet and valve. 



Storage of Fuel. Most oil heaters will burn about a 

 quart of oil per hour. Thirty hours should be about the 

 maximum that it will be necessary to burn the heaters 



