January, 1900.] 41 



a citrometer or an ordinary specific 

 gravity hydrometer. A description of 

 a scale prepared by Dr. Francis Watts 

 for use in ascertaining the strengths of 

 solutions of citric acid and of lime juice 

 by means of a hydrometer will be found 

 in the West Indian Bulletin (Vol. V, pp. 

 236-40), while a similar hydrometer 

 method is described in the Agricultural 

 Neivs (Vol. VI, p. 149.) The following 

 extracts are taken from these articles :— 



' In preparing concentrated lime juice 

 the concentration should be carried on 

 until a citrometer floating in the hot 

 juice (at boiling heat) indicates a density 

 of 60 p 



' As the citrometer is an instrument 

 but little known, difficulty has at times 

 been experienced in procuring it. Its 

 use, however, can be dispensed with, 

 and an ordinary specific gravity hydro- 

 meter the nature of which is universally 

 understood, can be substituted, by 

 making use of the fact that 60° on the 

 citrometer is equivalent to 1*243 on a 

 specific gravity hydrometer. 



'In this connexion the following scale 

 may be useful :-- 



sp. gr. 



50 o citrometer 





1*202 



51 





1*207 



52= 





1*211 



53 





1*215 



54 





1*219 



55= 





1*223 



56= 





1*227 



57° 





1*231 



58= 





1*235 



59* 





1*239 



60" 





1*243 



61° 





1*248 



62° 





1*256 



63° 





1*260 



'Suitable specific gravity hydrometers 

 graduated from 1*200 to 1*300 specific 

 gravity can be obtained from makers of 

 scientific instruments at a cost of about 

 2s. each.' 



Lime juice for concentration should, 

 when leaving the mill, be carefully 

 strained in order to remove all the seeds, 

 before it is run into vats. From the 

 vats it is run into the still to obtain the 

 oil, and afterwards to the tachyes to be 

 concentrated. 



It has lately been shown ( West Indian 

 Bulletin, Vol. VIII, p. 171) that lime 

 juice, carefully strained, and then settled 

 after distillation has obtained a special 

 market, and commands higher prices 

 than ordinary concentrated juice. 

 Every effort, therefore, should be made 

 by planters to ship a high-class product. 



Edible Products. 



The juice is shipped to New York or 

 Loudon in hogsheads of 52 gallons, 

 where it is tested and paid for according 

 to the citric acid contents. 



Buyers in London and New York pay 

 for citric acid, and not for impurities in 

 the juice. The presence of the latter 

 causes great trouble to manufacturers 

 of citric acid, and tends to bring prices 

 down. Lime juice should therefore 

 never be concentrated in iron tayches, 

 as the iron combines with it and lowers 

 the value of the product- 

 Concentrated juice testing 100 to 105 

 oz. per gallon made of well strained and 

 carefully settled lime juice is a black 

 and heavy, but not a dense, liquid. 

 When no care is taken to strain or settle 

 the juice, the product is black, and as 

 thick as molasses at the same degree of 

 concentration. 



Citrate of Limb. 

 In the manufacture of citrate of lime, 

 the juice on leaving the mill is carefully 

 strained, then distilled to obtain the 

 oil, and afterwards while still hot, it is 

 run into a wooden vat to be neutralized 

 with chalk. Before running iuto the 

 mixing vat, it would be an improve- 

 ment if the hot juice were passed 

 through filter bags. ( West Indian Bid- 

 letin, Vol. VIII, p. 167). At present 

 lavigated chalk is imported, but it is 

 hoped later to use mainly lime made 

 locally from coral. It is generally stated 

 that the process of neutralization should 

 be finished with chalk, but one authority 

 has said that finishing with lime, even 

 when chalk has been used to start with, 

 is to be recommended as there is thereby 

 a saving of time and a clearer indication 

 is obtained. Neutralizing vats are fitted 

 with perforated steam coils in order to 

 keep the juice hot, and to act as agitators 

 during the time chalk is being added, 

 during the washing process, and until 

 the citrate is finally run into the filter 

 bags. They must be large enough to 

 prevent loss from overflow by the foam- 

 ing effervescence which takes place when 

 chalk is added. 



Dr. Watts writing on this matter 

 says :— 



' A sufficient quantity of chalk is made 

 into a cream with water and the mixture 

 poured cautiously into the juice with 

 constant stirring, proceeding cautiously 

 as the acid is neutralised. To ascertain 

 how much chalk is to be used it is best 

 to proceed as follows : When the greater 

 part of the chalk has been added, the 

 mixture is well stirred and the efferve- 

 scence is allowed to subside; a small 

 quantity is then taken out and tested 

 by the addition of a little of the mixture 



