16 BULLETIN 49, HAWAII AGRICULTURAL EXPERIMENT STATION. 



definitely in storage. At present the preparation of citrate of lime 

 in the country where the fruit is grown is a step in the manufacture 

 of citric acid. The citrate is prepared from clear filtered lime 

 juice neutralized by the addition of chalk or lime. The juice must 

 be hot and the chalk or lime very fine and free from magnesium 

 and other impurities. The chalk or lime is stirred in water to the 

 consistency of cream, after which it is poured into the hot juice, 

 the whole being constantly stirred. When the chalk or lime is added 

 an active foaming or effervescence takes place, which diminishes 

 as the neutralization point is reached. The amount of chalk or lime 

 to be added may be determined by removing a small sample from 

 time to time and testing it by adding more chalk. This is repeated 

 until no active effervescence takes place. Finally, a few drops of 

 lime juice should be added to a sample of the mixture. If only 

 slight effervescence occurs the proper amount of chalk has been 

 added, but if strong foaming takes. place more juice should be added 

 to the mixture. The mixture should be heated to nearly the boiling" 

 point for a few minutes, when the citrate of lime will begin to fall 

 as a precipitate. The clear yellow liquid is then poured off and the 

 precipitate washed with hot water, after which it is dried and packed 

 for storage and shipment. Commercial citrate of lime contains 

 about 65 per cent of citric acid. 



Citric acid is obtained from the citrate of lime by adding dilute 

 sulphuric acid, which produces sulphate of lime, leaving citric acid 

 in solution. The solution is evaporated in leaden boilers until the 

 pure citric acid crystallizes out. Citric acid has many uses. 



Essential oils. — A very volatile essential oil of high flavor is ob- 

 tained from the rind of the lime. The market recognizes two classes 

 of oil, depending upon the method of extraction. The higher grade 

 of oil, or "otto," is extracted from the rind by hand pressure, the 

 fruits being rolled individually on a spiked funnel known as an 

 " ecuelle." The method is slow and requires a long time to collect 

 oil in any quantity. After the fruits have been so treated they 

 are milled and the juice and a further yield of oil are extracted by 

 pressure. The oil is then separated from the juice by distillation 

 and is considered as second-grade oil. 



Lime oil is in demand for flavoring extracts and perfumery. 



RECIPES FOR USING LIMES.' 



Lime juice makes an excellent flavoring for various kinds of food. 

 In addition to being substituted for vinegar in many recipes, it is 

 used as a seasoning for mayonnaise and the French dressing which 

 is served with many kinds of tropical fruits and w certain kinds 

 of fresh salads. It is also used to improve the flavor of ]ams, jellies, 

 and fruit butters. 



FRESH LIMES. 



Sound limes. 



Mason fruit jars having air-tight caps. 

 Select clean, sound fruit which has been cut from the tree |«^ a way as 

 to leave the little stem-end disks or "buttons" adhering to the fruit These 

 prevent ^ the entrance of fungus spores which cause decay To keep limes for 

 several weeks, place them in a fruit jar fitted with air-tight cap. 



agronomy of the station, for recipe 10. 



